73 replies to this topic

[DEAD MONEY]

OK so I have a 1986 Yanmar 1GM10 in my Soverel 33. We took it out of the boat (2 Hour Job) had it completely apart and rebuilt with New Main Bearing's, New Cylinder Head, Piston/Rings, Injector, every moving part was replaced and Painted etc, etc.....($1,200 in Parts). It is beautiful!!

Put in Boat (4 Hour Job hahah)and it started and Runs perfect. The problem is it will NOT get it's RPM's over 2,000. We need 3,000 to make any speed. Boat is underpowered as is and it needs to run at 3,000 to produce more power. It is totally put in correctly and throttle is wide open (there is no more movement left in the throttle as it is wide open).

It is still spitting Dirty water out of discharge. Someone told me the Exhaust is to blame.....How? and Where? What else could hinder engine from producing more RPM's ?? What can be done to increase RPM's?? Thanks....

[hard aground]

exhaust elbow could be blocked?

[mrgnstrn]

Is that 2000 RPM under load (i.e., in gear), or 2000 rpm under no load?

Which throttle adjuster is maxed out? The handle up on deck or the lever actually on the engine block?

If I were to guess, I'd say you reconnected the throttle cable to the engine differently, and somehow limited it's travel.

Or you need to adjust the no-load speed limiter setting. that's in the shop manual.

-M

[K38BOB]

Does the engine need a break in time for the rings to seat?

[DRIFTW00D]

Make sure the kill cable is not trying to kill or limit the engine.

[floating dutchman]

How did you set the injector timing?

That's where I'd look first. Seems an easy job looking at the manual, Just time it of the flywheel marks and add / remove shims as necessary. Haven't done it myself.

I assume you cleaned the prop, Could have turned into a little mussle farm while you were fixing the engine.

[DEAD MONEY]

exhaust elbow could be blocked?

Possible? will have dissemble ALL exhaust and replace or try to clean.

[DEAD MONEY]

Is that 2000 RPM under load (i.e., in gear), or 2000 rpm under no load?

Which throttle adjuster is maxed out? The handle up on deck or the lever actually on the engine block?

If I were to guess, I'd say you reconnected the throttle cable to the engine differently, and somehow limited it's travel.

Or you need to adjust the no-load speed limiter setting. that's in the shop manual.

-M

That's 2,000 RPM under load. The Throttle on the engine is Maxed out by using the shifter so it is hooked up correctly. When you manually try to get more throttle when engine is running (under load) you can't get any more (so logically the shifter is working correctly).

This is where myself and other installer got "stuck" (and Yes we are the original ones who took it out, and Yes I wrote notes.....but 6 months later...hahah)so we had another Friend Help us out. He is a Mechanic and put the shifter cables back. And Yes I did buy the $100 Shop manual, not that it would help me.

Tell me more about the "n0-load speed limiter setting" never heard of that, where/what is it ???

[DEAD MONEY]

Does the engine need a break in time for the rings to seat?

Not that I'm aware of. But even if it did I should still be able to get more RPM's out.

[DEAD MONEY]

Make sure the kill cable is not trying to kill or limit the engine.

They are far enough apart to NOT be an issue. We had the engine hood off and tried the shifter a thousand times to watch and see what is up with it......we thought it was to be at Fault as to why we can't get more Juice but it appears to be fine and working correctly!

[DEAD MONEY]

How did you set the injector timing?

That's where I'd look first. Seems an easy job looking at the manual, Just time it of the flywheel marks and add / remove shims as necessary. Haven't done it myself.

I assume you cleaned the prop, Could have turned into a little mussle farm while you were fixing the engine.

Hmmmm What's this you speak...."Injector Timing" ???? What the Hell is it?? Never heard of it.....you could be onto something here! Seriously we never did anything with Injector.....engine guy put rebuiult injector in the engine never knew it "had" to be adjusted......thanks!

I personally took Prop off. First time in 3 years and came off very easily (5 minute job). I greased the piss out of it with an expensive Marine paste oil and it was still coated in it. It was filthy w/growth but sanded it clean and put new zinc on.

[sailman]

Dead,

Here you go:

 1GM Injector Timing_1.JPG   78.25K   200 downloads

 1GM Injector Timing_2.JPG   37.93K   180 downloads

PM if you want the whole manual.

[DEAD MONEY]

Dead,

Here you go:

 1GM Injector Timing_1.JPG   78.25K   200 downloads

 1GM Injector Timing_2.JPG   37.93K   180 downloads

PM if you want the whole manual.

Thanks Sailman.....so my timing is off? and if it is adjusted it will create more RPM's ?

[mrgnstrn]

Is that 2000 RPM under load (i.e., in gear), or 2000 rpm under no load?

Which throttle adjuster is maxed out? The handle up on deck or the lever actually on the engine block?

If I were to guess, I'd say you reconnected the throttle cable to the engine differently, and somehow limited it's travel.

Or you need to adjust the no-load speed limiter setting. that's in the shop manual.

-M

That's 2,000 RPM under load. The Throttle on the engine is Maxed out by using the shifter so it is hooked up correctly. When you manually try to get more throttle when engine is running (under load) you can't get any more (so logically the shifter is working correctly).

This is where myself and other installer got "stuck" (and Yes we are the original ones who took it out, and Yes I wrote notes.....but 6 months later...hahah)so we had another Friend Help us out. He is a Mechanic and put the shifter cables back. And Yes I did buy the $100 Shop manual, not that it would help me.

Tell me more about the "n0-load speed limiter setting" never heard of that, where/what is it ???

since it seems like from your response, you can get to 3500 rpm when you are not in gear, it doesn't sound like the problem.

but if you need to know, here is the overall governor system, with the no-load-speed-limiter shown. there is a screw that is supposed to be factory adjusted, but if you replace a bunch of stuff, you may need readjustment.

 governor.pdf   89.79K   50 downloads


-M

[WarBird]

That's 2,000 RPM under load. The Throttle on the engine is Maxed out by using the shifter so it is hooked up correctly. When you manually try to get more throttle when engine is running (under load) you can't get any more (so logically the shifter is working correctly).

This is where myself and other installer got "stuck" (and Yes we are the original ones who took it out, and Yes I wrote notes.....but 6 months later...hahah)so we had another Friend Help us out. He is a Mechanic and put the shifter cables back. And Yes I did buy the $100 Shop manual, not that it would help me.

Tell me more about the "n0-load speed limiter setting" never heard of that, where/what is it ???

Because the shifter is fully forward does not mean that the fuel control lever on the injection pump is moved all the way to the maximum setting. From the responses, I am uncertain Money is getting enough no load rpms. If this is the case, that is IF, I would disconnect the throttle cable and see if there is more movement available (injection pump throttle lever) than the throttle cable travel allows. This is a simple check that you can do with the engine not running, or with a friend while the engine is running.

[Bucket]

If you are getting maximum revs with no load (roughly 3600 on a Yanmar tachometer, but only 2000 under load at the same throttle setting, it's likely the problem is either air in the fuel line or breathing. Your comment about dirty exhaust suggests a problem there; engines have to breathe out as well as in. That's where I'd start.

[longy]

If engine makes max revs in nuetral ,the engine is fine. Your prop is overloading the engine. Get a diver to buff out the prop & shaft, then get off the dock & let the boat move. Just being tied to the dock will keep your revs down. Remember it's a little engine. Black exhuast is unburnt diesel, anither sign of overloaded running conditions.

[Cavelamb]

If engine makes max revs in nuetral ,the engine is fine. Your prop is overloading the engine. Get a diver to buff out the prop & shaft, then get off the dock & let the boat move. Just being tied to the dock will keep your revs down. Remember it's a little engine. Black exhuast is unburnt diesel, anither sign of overloaded running conditions.

Prop - or transmission?

[damcoyote]

Had the same problem when I changed fuel filters out on my 1GM10 (Soverel 33). Check the fuel system for leaks where air is getting in. Mine was the O ring on the second filter.

[DEAD MONEY]

If engine makes max revs in nuetral ,the engine is fine. Your prop is overloading the engine. Get a diver to buff out the prop & shaft, then get off the dock & let the boat move. Just being tied to the dock will keep your revs down. Remember it's a little engine. Black exhuast is unburnt diesel, anither sign of overloaded running conditions.

Thanks.....been racin last month so very little time to play w/Engine.....it runs for so little time but had friend that works on Diesals look at it.

He turned Governor up a little and now get 2200 full out but when put in Neutral it will go ALL the way up to 3700 RPM's. So I definitely agree that the engine is running fine. I took the Prop off prior to launching and cleaned very thorughly so it is as clean as it was when originally put on.

Could be air leak but that's way over my head. Will try to disconnect throttle next.....thanks ALL !!

[Manana]

You should be able to achieve a higher RPM under way. The GM series of diesels has a very small flywheel and as such needs to run at a higher rpm. The power curve and fuel economy are farther up the rpm band(around 2850 according to Yanmar).

If you continue to run at only 2200 with a black exhaust all you will be doing is "coking" up your exhaust elbow. Which will cause even more power loss.

Don't just tolerate the problem. Get it fixed before you have to spend another 1.2 boat units...

[_dinsdale_]

Had a similar problem. Under-reving with lots of black smoke. Cleaned the prop... no difference. Then had the prop "repitched", problem solved. How the prop changed pitch orginally? No idea.But with the wrong pitch the prop wouldn't spin efficiently, held the engine back and exhaust spewed unburned fuel.

[mrgnstrn]

What about reverse? can you make rated RPM in reverse?

this is a big time long shot, but is it possible that the prop got installed backwards? maybe the trailing and leading edges got flipped. it would still pitch in teh direction to make you go FWD, but shit-i-ly.

I don't even know if it's possible to put a prop on backwards. but I have not seen every prop in the world, so maybe your's is one that can????

-M

[longy]

Impossible to pt a prop on 'backwards", the shaft hole is tapered. But he is still over propped.

[mrgnstrn]

Impossible to pt a prop on 'backwards", the shaft hole is tapered. But he is still over propped.

yeah...i've never seen a fixed prop *without* a taper, and I can't imagine that it's possible to install a folding prop with the blades backwards.

dunno about every other kind of prop. but I doubt it's possible too. a total shot in the dark.


the wild card here is that the OP says everything was fine before they took the engine out and put it back in. It didn't sound like the prop changed in the middle.

Maybe Dead Money can recall, was everything *actually* fine before engine work? I doubt it because why else would you take the engine out in the first place?

-M

[bulkleycorp]

If all is well in neutral, what about the tranny? Or how about stuffing box or cutless bearing being wrong size or causing friction??

Only time this happened to my 1gm-10 was a heavily barnacled prop. Once cleaned she hit 3k plus rpm.

[Ishmael]

Impossible to pt a prop on 'backwards", the shaft hole is tapered. But he is still over propped.

yeah...i've never seen a fixed prop *without* a taper, and I can't imagine that it's possible to install a folding prop with the blades backwards.

dunno about every other kind of prop. but I doubt it's possible too. a total shot in the dark.


the wild card here is that the OP says everything was fine before they took the engine out and put it back in. It didn't sound like the prop changed in the middle.

Maybe Dead Money can recall, was everything *actually* fine before engine work? I doubt it because why else would you take the engine out in the first place?

-M

It is possible to install a Max Prop with the blades backwards, or at zero pitch, or any number of other things that will prevent propulsion. I know this from personal experience.

[bheintz]

We had a simular problem with our 1GM10: no load engine could go up to 30k, under load engine maxed out at about 25k rpm

While trying to prime the fuel lines I noticed that the Fuel Feed Pump was not working properly (removal and inspection -> bad gasket)

Since Yanmar no longer offers rebuild kits for Feed Pump we replaced the unit (about $85). Pretty easy on a Soverel 33.

After replacing the pump we pegged the Tach at the dock.

[DEAD MONEY]

You should be able to achieve a higher RPM under way. The GM series of diesels has a very small flywheel and as such needs to run at a higher rpm. The power curve and fuel economy are farther up the rpm band(around 2850 according to Yanmar).

If you continue to run at only 2200 with a black exhaust all you will be doing is "coking" up your exhaust elbow. Which will cause even more power loss.

Don't just tolerate the problem. Get it fixed before you have to spend another 1.2 boat units...

We broke a Oil Line last year so ALL (and I do mean ALL) the Oil went into the Bilge and went out the back end (yes I know a bad environmental thing) so ALL the hoses had Oil running thru so there is really NO oil/Diesal not being burnt effcientally.

[DEAD MONEY]

Had a similar problem. Under-reving with lots of black smoke. Cleaned the prop... no difference. Then had the prop "repitched", problem solved. How the prop changed pitch orginally? No idea.But with the wrong pitch the prop wouldn't spin efficiently, held the engine back and exhaust spewed unburned fuel.

This whole process reminds me of a Game Show like "Guess my Line"......Nope have NOT changed the Prop or Pitch of said Prop. It is relitively New (2 years) and is a Folding/Feathering 2 Blade Vari-Prop w/Gears. Very nice!!

[DEAD MONEY]

What about reverse? can you make rated RPM in reverse?

this is a big time long shot, but is it possible that the prop got installed backwards? maybe the trailing and leading edges got flipped. it would still pitch in teh direction to make you go FWD, but shit-i-ly.

I don't even know if it's possible to put a prop on backwards. but I have not seen every prop in the world, so maybe your's is one that can????

-M

Ummmm I'm Dumb NOT Stupid. I took it off and cleaned than I put it on.....it can only go on ONE way!! So even a Dumbie like me can't screw it up.....Next!!

[DEAD MONEY]

Impossible to pt a prop on 'backwards", the shaft hole is tapered. But he is still over propped.

yeah...i've never seen a fixed prop *without* a taper, and I can't imagine that it's possible to install a folding prop with the blades backwards.

dunno about every other kind of prop. but I doubt it's possible too. a total shot in the dark.


the wild card here is that the OP says everything was fine before they took the engine out and put it back in. It didn't sound like the prop changed in the middle.

Maybe Dead Money can recall, was everything *actually* fine before engine work? I doubt it because why else would you take the engine out in the first place?

-M

Engine was 20 yrs old. It worked great with the same prop than slowly started to go till it eventually was smoking too much. I pulled it because that is the right way to overhaul it completely.

Replaced every moving part, Cylinder Head had hole in it from saltwater, injector was fucked and was "pissing" Diesal,not atomizing it.....so it is perfect now, just need a little more power Scotty!!

[DEAD MONEY]

If all is well in neutral, what about the tranny? Or how about stuffing box or cutless bearing being wrong size or causing friction??

Only time this happened to my 1gm-10 was a heavily barnacled prop. Once cleaned she hit 3k plus rpm.

Nope not studffing box, or Cytlas Bearing....I replaced both last year and they worked great.

Next......

[DEAD MONEY]

We had a simular problem with our 1GM10: no load engine could go up to 30k, under load engine maxed out at about 25k rpm

While trying to prime the fuel lines I noticed that the Fuel Feed Pump was not working properly (removal and inspection -> bad gasket)

Since Yanmar no longer offers rebuild kits for Feed Pump we replaced the unit (about $85). Pretty easy on a Soverel 33.

After replacing the pump we pegged the Tach at the dock.

Hmmm I think we might have a winner!!! I did NOT know there was a "Feed Pump" so I did NOT replace. Is there a way to Test this prior to replacing the Pump Mr BHeintz?? Thanks!! Maybe you can look at it ??

[sailman]

We had a simular problem with our 1GM10: no load engine could go up to 30k, under load engine maxed out at about 25k rpm

While trying to prime the fuel lines I noticed that the Fuel Feed Pump was not working properly (removal and inspection -> bad gasket)

Since Yanmar no longer offers rebuild kits for Feed Pump we replaced the unit (about $85). Pretty easy on a Soverel 33.

After replacing the pump we pegged the Tach at the dock.

Hmmm I think we might have a winner!!! I did NOT know there was a "Feed Pump" so I did NOT replace. Is there a way to Test this prior to replacing the Pump Mr BHeintz?? Thanks!! Maybe you can look at it ??

I believe that the fuel priming pump and feed pump are one in the same. Torresen Marine has parts.

[bheintz]

We had a simular problem with our 1GM10: no load engine could go up to 30k, under load engine maxed out at about 25k rpm

While trying to prime the fuel lines I noticed that the Fuel Feed Pump was not working properly (removal and inspection -> bad gasket)

Since Yanmar no longer offers rebuild kits for Feed Pump we replaced the unit (about $85). Pretty easy on a Soverel 33.

After replacing the pump we pegged the Tach at the dock.

Hmmm I think we might have a winner!!! I did NOT know there was a "Feed Pump" so I did NOT replace. Is there a way to Test this prior to replacing the Pump Mr BHeintz?? Thanks!! Maybe you can look at it ??

I believe that the fuel priming pump and feed pump are one in the same. Torresen Marine has parts.

Yes, "Feed Pump" and "Priming Pump" are the same. The pump is driven by an arm the rides on the cam shaft (essentially a diaphragm pump.) There is also a finger lever that you can use to bleed the filter and low pressure lines.

If the finger lever does not work, then most likely the diaphragm is cracked. You can test this on the engine by cracking the Filter Vent, or off the engine with the suction hose into a pail of fuel (dining room table is a good location).

See pages 3-30 - 3-32 of 1GM10 Service Manual (fig 37 of 1GM10 Parts Cat.) Part #'s 105582-52010 and 121520-01851

[DEAD MONEY]

tell you what....you look at it and tell me your thoughts and I'll give you some of the BEST Clams Casino you ever had.....whatdaya say Mate??

[longy]

Um, wasnt it stated earlier that the engine will reach max RPM in neutral?? If so, it's not a fuel supply issue.

[sailman]

Um, wasnt it stated earlier that the engine will reach max RPM in neutral?? If so, it's not a fuel supply issue.

It certainly could be, fuel flow rate is different under load. There could be a leak in the LP pump diaphram that allows enough fuel under no load but not enough under full load.

[blofeld]

sounds like its a fuel prob to me . dead . Get all new gaskets for the fuel system and I'll change them . We also have to look at the fuel lines from the tank they could be all clogged up with garbage. thanks everyone for the help . goose

[WarBird]

This may not be pertinent!! The engine was out of the boat? Did the transmission come out of the boat also? I am not sure of the workings but, I heard a sound, slight whining, on a friend's boat as he motored away. An aged and vastly experienced surveyor said the reverse cone might be dragging in the transmission and that an adjustment(don't know inside or out) was needed. Something like that or overfilling the transmission with oil would cause a problem like what you seem to be seeing.

[DEAD MONEY]

This may not be pertinent!! The engine was out of the boat? Did the transmission come out of the boat also? I am not sure of the workings but, I heard a sound, slight whining, on a friend's boat as he motored away. An aged and vastly experienced surveyor said the reverse cone might be dragging in the transmission and that an adjustment(don't know inside or out) was needed. Something like that or overfilling the transmission with oil would cause a problem like what you seem to be seeing.

Yes the Tranny was (and is) attached to the back of the engine and it's fluid has never been less than full ALL the time. So, Yes when the engine was pulled it was pulled also...pretty easy when it's a One Banger!

I think it is the Fuel System. We fix it before the Boat is pulled for the season (I Hope!!)....

[rtb]

RUN IT! when we bought our Cape Dory 25D with the 1GM the PO stated that one of the thing he really liked about his slip was that he could be sailing after backing out of the slip. And apparently that's what he did alot.

The 1GM would not get over 2500 rpm w/o lots of black smoke. The cure was to motor sail for 4 hours followed by an hour of 2500 rpm run. Afterward she would spin well over 3k and Seraph would now reach hull speed.

Every time you use the 1GM be sure to get it up to temp. Do not lug it around. Do not let it idle for long periods. IT AIN"T A DIESEL TRUCK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[mrgnstrn]

Impossible to pt a prop on 'backwards", the shaft hole is tapered. But he is still over propped.

yeah...i've never seen a fixed prop *without* a taper, and I can't imagine that it's possible to install a folding prop with the blades backwards.dunno about every other kind of prop. but I doubt it's possible too. a total shot in the dark.the wild card here is that the OP says everything was fine before they took the engine out and put it back in. It didn't sound like the prop changed in the middle.Maybe Dead Money can recall, was everything *actually* fine before engine work? I doubt it because why else would you take the engine out in the first place?-M

It is possible to install a Max Prop with the blades backwards, or at zero pitch, or any number of other things that will prevent propulsion. I know this from personal experience.

What about reverse? can you make rated RPM in reverse?this is a big time long shot, but is it possible that the prop got installed backwards? maybe the trailing and leading edges got flipped. it would still pitch in teh direction to make you go FWD, but shit-i-ly.I don't even know if it's possible to put a prop on backwards. but I have not seen every prop in the world, so maybe your's is one that can????-M

Ummmm I'm Dumb NOT Stupid. I took it off and cleaned than I put it on.....it can only go on ONE way!! So even a Dumbie like me can't screw it up.....Next!!

see above.

[Dave]

sounds like its a fuel prob to me . dead . Get all new gaskets for the fuel system and I'll change them . We also have to look at the fuel lines from the tank they could be all clogged up with garbage. thanks everyone for the help . goose

I've had similar issues with my 1GM10. All fixed fairly easily when you find the culprit. Twice it was the copper washers on the fuel filter. Once you changed the filter if they are slightly warped they could leak fuel out and air in. Now I replace them once per year when I change the fuel filter.

On the way out of Screwpile this year (while facing a 14+ hour motor home into a light 5 kt headwind) the engine konked out twice before leaving Solomons. No fuel in the filter. The culpit, the metal L connecting the fuel hose to the motor was loose. Tightened it up and we were good to go for 14 hours.

It doesn't take much of a leak to do it.

[marmalade]

Last night on a delivery to get our Soverel 27 with a 1GM10 to Annapolis for the SMC Governor's Cup the engine started acting up. When leaving North East the engine would only rev to 2700 not the typical 3000. We were cruising at 2500 about 20 nm into the trip without any other problems and just as we were crossing the shipping channel the engine just slowed down to about 1000 rpm even though the throttle had not been adjusted. After a few minutes of playing with the throttle it was running at 2500 rpms like nothing had happened. About 2hours later the same thing happened but this time it would not run over 1000 rpms.

After changing the fuel filter and checking the fuel hoses I ended up taking apart the Fuel Feed Pump Assembly and it turns out there is a little part (disk) that is held in place with two small screws. This piece holds what looks to be two one-way valves in place on the two of the pump assemble. One of the screws backed out and the disk broke ended up allowing the intake valve to fall out. We jury rigged it after about thirty five minutes but a new pump assembly has been ordered.

Maybe this could be your problem.

[DEAD MONEY]

RUN IT! when we bought our Cape Dory 25D with the 1GM the PO stated that one of the thing he really liked about his slip was that he could be sailing after backing out of the slip. And apparently that's what he did alot.

The 1GM would not get over 2500 rpm w/o lots of black smoke. The cure was to motor sail for 4 hours followed by an hour of 2500 rpm run. Afterward she would spin well over 3k and Seraph would now reach hull speed.

Every time you use the 1GM be sure to get it up to temp. Do not lug it around. Do not let it idle for long periods. IT AIN"T A DIESEL TRUCK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I usually start and run the engine about 5 minutes before leaving the Dock. I ALWAYS have it in Gear and have the Engine under Load at ALL times. A Diesal Mechanic told me this, not too sure if correct but hell why not.

When we are motoring we always put the peddle to the metal at ALL times....all 9.9 Horses.

[Overbored]

I was having trouble with the 1gm10 in my Soverel 33 for the last 6 mounths. some times it would run fine and other days it would run slow with no power. checked everthing on the engine and finally decided to check all the fuel lines and the tank. the problem was the fuel pick up tube which had a plastic tube with a rubber hose crimmped on the end. the hose was soft and was colapsing cutting down the fuel flow.

[40grit]

I have rebuilt a number of these motors, same deal, everything new and perfect, in and out all good. problem, the motor will not come up to rpm? I finally tracked it down to my pump re builder,he was following some specification within his farm manual and it was the governor, its happened a couple of times. play with the screw you will get it.

[DEAD MONEY]

Fast Forward.....Engine still NOT performing correctly....not getting up to 3,000 RPM's and still spitting Dirty Water out Exhaust.

Hired a Mechanic to look at it.....He says Engine is "Overpropped"! Prop is too Big (so he says)for the Engine. I told him it is the Same Prop that has been in the Boat last 5 years and worked fine prior to Re-Build. It got up to correct RPM's and Exhaust was Clear. Now exhaust is Black from unburnt Diesal fuel. Asked how/why/what could change engine performance and he had no clue.....ideas??? Engine gets up to 3600 RPM's when in Neutral but in gear only 2,000 RPM.

Thanks!! Don

[Heriberto]

Rebuilt fuel pump too?

[Mr. Fixit's brother,, Mr. Fixit]

One quick question. Is the shut down cable connected to the injector pump. I had a similar situation and after beating my head against a bulkhead for a day figured out the shutdown wasn't swinging all the way back into place. Quick check,

[Overbored]

Fast Forward.....Engine still NOT performing correctly....not getting up to 3,000 RPM's and still spitting Dirty Water out Exhaust.

Hired a Mechanic to look at it.....He says Engine is "Overpropped"! Prop is too Big (so he says)for the Engine. I told him it is the Same Prop that has been in the Boat last 5 years and worked fine prior to Re-Build. It got up to correct RPM's and Exhaust was Clear. Now exhaust is Black from unburnt Diesal fuel. Asked how/why/what could change engine performance and he had no clue.....ideas??? Engine gets up to 3600 RPM's when in Neutral but in gear only 2,000 RPM.

Thanks!! Don

Check timing and injection nozzel. was it rebuilt? new one is $100 so not worth rebuilding. the rebuild parts are around $75 .check also the valve clearance. make sure the lifters are held in toward the center of the engine when you check this as with the valve cover they will slide over and the clearance will be incorrect. the so called mechanic the PO used did not know this and had things very wrong.

[Paul Hellings]

I know you said exhaust is clear, but I've seen a couple of Yanmars with clogged exhaust elbows and they did exactly what you describe. One was a 1 GM10 and the other was a 2GM15. Make sure the elbow is clear.

[DEAD MONEY]

Bought New Fuel Pump and installed. Still cannot get RPM's over 2,200.Exhaust still spitting Dirty unburnt fuel.

[sailman]

Bought New Fuel Pump and installed. Still cannot get RPM's over 2,200.Exhaust still spitting Dirty unburnt fuel.

Dead,

Unburnt fuel in the exhaust would rule out a governor issue, the governor will limit the rack but will not affect combustion. Is the timing correct? Since you rebuilt everything that eliminates the usual suspects, most likely. Unburnt fuel is incomplete combustion which is either lack of air or too much fuel or a very poor atomization from the injector. How far is the exhaust hose run from the engine? Did that hose get changed? Could there be a restriction in that hose?

[Mr. Fixit's brother,, Mr. Fixit]

Bought New Fuel Pump and installed. Still cannot get RPM's over 2,200.Exhaust still spitting Dirty unburnt fuel.

Dead,

Unburnt fuel in the exhaust would rule out a governor issue, the governor will limit the rack but will not affect combustion. Is the timing correct? Since you rebuilt everything that eliminates the usual suspects, most likely. Unburnt fuel is incomplete combustion which is either lack of air or too much fuel or a very poor atomization from the injector. How far is the exhaust hose run from the engine? Did that hose get changed? Could there be a restriction in that hose?

I've definitely seen the inner ply of an exhaust hose collapse and restrict flow.

[BobJ]

Air in the fuel system - had it happen 3-4 times with my 1GM10.

Scroll down for bleeding instructions.

[Overbored]

did you check the fuel supply line inside the tank? the rubber hose on the end may have colasped. did you check injector timing ? timing is set with shims under the injection pump. check the valve clearance. when setting you have to hold the rocker on the shaft towards the center of the head. the boss inside the valve cover keeps the rocker on the shaft when the cover is in place and when checking the clearance with the cover off the rocker tends to slides off a bit and this effects the setting a lot.

[DEAD MONEY]

hmmm very Logical. I will have someone with more Mechanical ability look at these issues.....thanks!!

[floating dutchman]

How did you set the injector timing?

That's where I'd look first. Seems an easy job looking at the manual, Just time it of the flywheel marks and add / remove shims as necessary. Haven't done it myself.

I assume you cleaned the prop, Could have turned into a little mussle farm while you were fixing the engine.

Many have said timing, Have you cheacked it yet?

[DEAD MONEY]

put engine in reverse at Dock yest and it ran at 2900RPM's. In forward it still only gets to 2,000rpm's. what's up with that??

[Soñadora]

How did you 'clean' your prop? Did you do any polishing or anything that would be destructive to the prop? Sounds like maybe some major cavitation. Was your pop pitted on one side?

[sailman]

put engine in reverse at Dock yest and it ran at 2900RPM's. In forward it still only gets to 2,000rpm's. what's up with that??

First check the linkage to make sure you are fully engaging the forward direction, take the linkage off and shift it with your hand to make sure you have full travel and try the same test. If it still fails to get up to RPM then I would say your problem lies at the damper plate or spring plate. The plate transfers the rotation from the engine to the desired gear set (FWD / REV). If the plate is offset then one side will get a greater amount of torque.


 hurth.jpg   159.76K   1 downloads

[Frogwatch]

GAWD, the same prob on my 1GM drove me nuts. I bled the fuel system till I could do it blindfolded. Replaced all filters, set idle adjustment and throttle max at the engine, forget doing it at the shifter, set the timing with the shims, adjusted the valve clearance, checked for clogged exhaust elbow, rigged a gadget to check compression, replaced the injector and injection pump. Tried three diff mechanics. Finally, one mechanic came along with an IR thermometer and pointed it at the waterlift exhaust and told me it was partially glogged. I think I replaced it and it worked but cannot remember. This was on a 6.5 hp 1GM on a 7700 lb boat. Eventually, I replaced it with a 2GM13 for more power for dealing with thunderstorms.

[Innocent Bystander]

put engine in reverse at Dock yest and it ran at 2900RPM's. In forward it still only gets to 2,000rpm's. what's up with that??

Many transmissions have different ratios in forward and reverse and many feathering props have a lower pitch stop in reverse than forward. Still sounds over propped for the power being generated.

3600 rpm in neutral tells you governor is ok but it doesn't take much power to get high rpm with no load.

[Overbored]

put engine in reverse at Dock yest and it ran at 2900RPM's. In forward it still only gets to 2,000rpm's. what's up with that??

Do you have a folding prop? All the Mumm 36 should have a folding prop, Folding props do not open all the way when in reverse and there for do not require as much HP to drive them up to a higher RPM. Centrifugal force is trying to opening the prop and the water is trying to close the prop. Also static RPM ( boat tied to dock ) will always be lower than when the boat is moving thru the water.

[jerseyguy]

Had a similar but not identical problem with a Yanmar 2GM. Turned out that the brass fitting at the end of the fuel line, where it connected to the fuel tank had a small crack in it. Was letting air into the system. Replaced the fuel line and all was well.

[jim lee]

Did you ever get the poor thing fixed? 'Cause it sounds a lot like your cam timing is a tooth or so off. Does it idle really really well? Delightful idling and no real power are signs of bad valve alignment. Well, that and valves through piston tops, but that depends on the engine design and how far its off.

-jim lee

[mid-fleet buoy racer]

I also have to suspect the mixing elbow.. This sounds exactly like that problem.. replace the mixing elbow...


mfbr

[CJV]

Did you ever sort out your issues? I've had similar ones plaguing my 1GM10, due to air leaks in the fuel system between the primary and secondary filters. Must ensure you don't over-torque the bleed screws on the secondary filter.

 

Now I have a stuck exhaust valve preventing the engine from waking up after the long winter. Anyone got tips on freeing up a valve? I've used a heat gun and will try penetrating oil next...

[opa1]

This reinforces my decision to go to an outboard.  My luck with an inboard is lousy, at best.

[sailman]

Did you ever sort out your issues? I've had similar ones plaguing my 1GM10, due to air leaks in the fuel system between the primary and secondary filters. Must ensure you don't over-torque the bleed screws on the secondary filter.

 

Now I have a stuck exhaust valve preventing the engine from waking up after the long winter. Anyone got tips on freeing up a valve? I've used a heat gun and will try penetrating oil next...

PB Blaster!

[CJV]

Did you ever sort out your issues? I've had similar ones plaguing my 1GM10, due to air leaks in the fuel system between the primary and secondary filters. Must ensure you don't over-torque the bleed screws on the secondary filter.

 

Now I have a stuck exhaust valve preventing the engine from waking up after the long winter. Anyone got tips on freeing up a valve? I've used a heat gun and will try penetrating oil next...

PB Blaster!

well, it turned out to be a poorly installed fuel feed pump. somehow it was interfering with one of the valves, not sure which, and there was no compression. had to remove it and re-install it a couple of times before it would allow proper compression.

Looking at this diagram and peering thru the fitting hole, i can't see how it could happen...

but it works now, so, whatever.