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lecokev

Yanmar 3GM30 troubles..

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I think I've narrowed this down, but I'll post it anyway.

 

Yanmar 3GM is sucking the primary & secondary fuel filters practically dry. I went though most of the system and ruled out air/bad hoses and changed filters. Even cleared the vent. (it wasn't clogged) The only thing I didn't do was take apart the lead from the tank. We ran out of time since we were in MD to bring the boat up to North NJ.

 

This thing has a lot going on in the fuel system for a 35' C&C. Fuel polisher system, Algae-X conditioner magnet at the tank.

 

The only thing I'm left with is a clog somewhere in the fuel supply line. If I prime & bleed it runs like a champ. (A tad rich, but no issue I think) All I'm left to do is go after the tank. I'm not new to these engines, but I'm no pro mechanic.

 

The polisher system doesn't want to turn on either. Maybe that has something to do with it. I'm not very familiar with them, but it's pretty straightforward to me. The fuel supply line runs through a stopcock.

 

Any other ideas minions??

 

@Rail Meat.. If I remember correctly, this is your old boat. 'Indigo'. Your PMbox is full apparently.

 

Thanks.

 

-Kevin

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Kevin,

 

Double check the line up for the polishing system and main fuel. Make sure the polishing is isolated and that the supply and return are lined up correctly. Does the filter have a priming pump, Racor type? Does it prime easily after it is sucked dry by the engine? Is the tank level higher than the filter?

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Would it be normal for one primer pump to support the polisher and the engine or even boxed in with the polisher? Something tells me that I should have dug deeper into the polisher. I'm questioning my memory on how lines were run now... it was tight in there.

 

The tank is directly aft of the engine & polisher. Bottom is roughly level with the engine block, higher than the primary engine filter. That's low.

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the "Algae-X conditioner magnet" etc suggest that there has been problems with algae (which is very commen). If so, one of the first ideas comming into mind is clogging prior to the filters (as you already have deducted).

 

So, this is just in supporting your ideas.

 

/J

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Fuel line goes from tank through the magnet (installed right at the 90 from the tank) to the switch for polisher/engine.

 

I still think I could have crossed lines between a priming pump & the switch, but I doubt it.

 

Lowers it down a primer pump or a clog I guess. I should snap pictures. Lots of fuel lines in there...

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I was able to limp the boat in by simply bleeding. It ran well after not being used for a couple of hours also, but not for long. I think that rules out any pumps.

 

...Into the tank I go if I get back down there I guess.

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If this just started happening after you changed lines around I would go back at the polishing system and valve line up. Maybe take the polishing loop completely out of the picture and then run the engine.

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If this just started happening after you changed lines around I would go back at the polishing system and valve line up. Maybe take the polishing loop completely out of the picture and then run the engine.

 

I didn't change lines around. I suggested removing the polisher as well as running the engine off of a fuel can, thus eliminating both. I would have happily run off of a yellow can or two to make the 200 miles. We just ran out of time and came home. I really only got 1/2 a day to work on this. Logistics & location were an issue.

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Ok, then I would just take everything else out of the system and just run from tank to filter to engine and back to tank. That way you have gone over each line and you eliminate all other opportunities for failure.

 

If this just started happening after you changed lines around I would go back at the polishing system and valve line up. Maybe take the polishing loop completely out of the picture and then run the engine.

 

I didn't change lines around. I suggested removing the polisher as well as running the engine off of a fuel can, thus eliminating both. I would have happily run off of a yellow can or two to make the 200 miles. We just ran out of time and came home. I really only got 1/2 a day to work on this. Logistics & location were an issue.

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Ok, then I would just take everything else out of the system and just run from tank to filter to engine and back to tank. That way you have gone over each line and you eliminate all other opportunities for failure.

 

If this just started happening after you changed lines around I would go back at the polishing system and valve line up. Maybe take the polishing loop completely out of the picture and then run the engine.

 

I didn't change lines around. I suggested removing the polisher as well as running the engine off of a fuel can, thus eliminating both. I would have happily run off of a yellow can or two to make the 200 miles. We just ran out of time and came home. I really only got 1/2 a day to work on this. Logistics & location were an issue.

 

I helped bring the boat down in October easily. Mostly under power and everything was fine. The boat was finally splashed two weeks ago. "Spring's demons" in July. Either I'll try & clear the tank or just make a can setup.

 

I'm going to recommend removing the polisher. It's just not necessary. YMMV.

 

Thanks all..

 

-kl

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If you want to rule out a clog on the line form the tank to the filters, you could disconnec the fuekl line at the first filter and use an air pump to blow air through the fuel line into the tank. (a pump used for infloating dinghies works great). If it does not take too much effor and you hear bubbles in the tank you know that the the line is clearand that the pickup is imersed in fuel. This may also clear a clogged pickup and get you going for now.

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I don't remember seeing you say that you checked that the filter were clean...I assume you did that easy step.

 

Other dumb things I've done on my 35' C&C with a 3GM:

 

---not re-open the fuel valve at the tank after mucking with the filters

---had left the filter bowl drain open without refilling the system.

--- not reconnected fuel lines to the tank after mucking with them.

check those...it's easy to screw up.

 

your description of "sucking the filters dry" is odd. if there was a blockage in the system, the engine would just draw a vacuum on the tubing/filter/piping up to the clog, and then die....or limp along unde low power only. but it wouldn't suck air in there.

....unless....

if there is actually *air* in the filters, it had to come from somewhere, and i'd look again for a leak...

 

If you can actually prime the filters from the fuel tank, I would *not* think it possible for the fuel pickup tube to be broken...you wouldn't be able to prime the system......unless you a priming the system from a separate source of fuel (jerry jug).

 

what part of MD is the boat in now...lots of anarchist in this part of the country.

 

-M

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The fuel pickup tube in the tank may have a screen on the end of it. If that clogs or is partially blocked you'll have issues like this. Check that by removing the pickup from the tank if that is possible. Or chase the pickup out with something like 12 or 10 gauge wire, run down into it. If it stops, there's a screen. You may be able to poke through it to relieve the clog.

 

--Kevin

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The fuel pickup tube in the tank may have a screen on the end of it. If that clogs or is partially blocked you'll have issues like this. Check that by removing the pickup from the tank if that is possible. Or chase the pickup out with something like 12 or 10 gauge wire, run down into it. If it stops, there's a screen. You may be able to poke through it to relieve the clog.

 

--Kevin

 

 

if it is clogged, probably the only way to fix it is to blow backwards thru it (via the fuel hose). get ready for the awesome taste of exxon's finest.

 

m

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The fuel pickup tube in the tank may have a screen on the end of it. If that clogs or is partially blocked you'll have issues like this. Check that by removing the pickup from the tank if that is possible. Or chase the pickup out with something like 12 or 10 gauge wire, run down into it. If it stops, there's a screen. You may be able to poke through it to relieve the clog.

 

--Kevin

 

+2 , I've had two different boats which had clogs at the bottom of the fuel pickup. Most pickups have a small spring-like filter at the bottom, and assuming there is any algae growth floating around in the tank, it eventually gets sucked into that filter and stops up the inlet.

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Air entering the fuel line might cause the symptoms. Had a similar problem coming from Charleston to Annapolis. Rigged a jerry can suction/return to get home.

 

Once home, I put a temporary electric gear pump on the system to pump through the lines to identify the source of the leak.

 

The o-ring/plug gasket in the fuel brass cutoff valve at the tank had rotted and was letting in air. Very subtle. New valve, no problem. Now I'm going to replace those valves every 5 years.

 

Good luck.

 

P

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