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GeorgB

Yanmar cranks but doesn't start, help with troubleshooting needed

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I have a Yanmar 3JH4e engine from 2006. Returning from a breezy daysail yesterday it wouldn't start. Engine worked fine earlier during the day, no strange noise or smoke, normal speed and revs.

 

When i try to start the engine it cranks slowly but doesn't start.

 

I think i've checked the most obvious things. There is fuel in the tank, the start battery is charged and tested, engine oil looks good, no dirt in primary fuel filter and i've bled the fuel system.

 

Any suggestions?

 

 

 

 

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Air in fuel system ...bleed .....painted bleed points yellow

 

plus perhaps

 

add small 12 volt fuel pump to line to help bleed air from system

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check your fuel line. Not only air, but also water, or anything stopping. (=> filters)

 

Worked fine earlier the same day? Tehn something has happened since ...

very obvious: motor was stopped. Using .... and then?

 

/J

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Yes, we left the harbour by engine, hoisted sails, let engine run in neutral for five minutes and then turned it off. We sailed for a few hours. Wind was 10-14m/s, i'm thinking it could be something caused by heeling/boat movement.

 

I've bled the air from the fuel line and the the water separator is clean and free of water. I'll check the engine filter tomorrow.

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Had a similar situation with my Volvo Penta MD a few years back - after a panicked scramble about the engine trying to figure out what happened, it turned out to be the stop control that hadn't been fully returned to the 'run' position after stopping the engine earlier...

 

I don't know how Yanmar's are stopped, but perhaps an easily overlooked thing to check before starting to wield spanners all over the fuel system!

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Thanks for the reply. I thought it might be related to the stop somehow, but the engine is stopped by a solenoid switch.

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solenoid switches can fail! I suspect it controls a mechanical action on the fuel supply in order to stop the engine, so it should be possible to verify that to see if that is what is causing the issue - but to be honest I'm speculating a bit here. Anyone else around that is more familiar with the stop mechanism on Yanmars?

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Kind of off topic, but I pulled on an outboard today, like ten or so times, till I realized I hadn't replaced the lanyard pull. My motor is far better than it's operator.

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I had a similar problem on a Nuiversla M-20, and the stop engine system was what it eventually turned out to be.

 

The stop engine handle at the control station was in the "run" position, but the mechanism at the motor was stuck. A little WD40 and some working it back and forth manually, and voila......

solenoid switches can fail! I suspect it controls a mechanical action on the fuel supply in order to stop the engine, so it should be possible to verify that to see if that is what is causing the issue - but to be honest I'm speculating a bit here. Anyone else around that is more familiar with the stop mechanism on Yanmars?



"Nuiversla M-20,"?????

 

UNIVERSAL M-20....

 

I had a similar problem on a Nuiversla M-20, and the stop engine system was what it eventually turned out to be.

 

The stop engine handle at the control station was in the "run" position, but the mechanism at the motor was stuck. A little WD40 and some working it back and forth manually, and voila......

solenoid switches can fail! I suspect it controls a mechanical action on the fuel supply in order to stop the engine, so it should be possible to verify that to see if that is what is causing the issue - but to be honest I'm speculating a bit here. Anyone else around that is more familiar with the stop mechanism on Yanmars?

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Lots of reasons engines won't start, but if they are not the obvious ones (no cranking, air in fuel line, etc) then an electrical fault is likely.

I've had poor connection to starter (only starts when battery is fully charged), engine won't stop (stop solenoid faulty), faulty key switch, etc on my Yanmar. I'd like to think I've fixed all the poor electrical connections on my 20yr old engine, but then something new occurs.......

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Stop is a solenoid on the engine but has a manual push as well (orange color i think). It might be worth a check that it sprung back correctly.

 

If it turns over more slowly than normal, the start battery may be tired. Especially if any of the boats systems (instruments) were powered while sailing from that battery or with a the battery switch in "both".

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Cranking slowly points more to a battery or starter issue, most likely battery. First thing. Pull the terminals and wire brush everything.

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Thanks for all the replies so far. After working on the engine for three hours today i'm sure there's an electrical problem affecting the starter. I get ∼13v at the starter solenoid b (+) terminal. When cranking the engine, the voltage at the starter engine side of the solenoid switch only measures ∼8v. I removed all the connecting cables, cleaned them once more as well as the engine ground cable connections. No cigar.

 

I guess next step is removing the starter engine and cracking the solenoid open to clean the points. Any other ideas or suggestions on taking the solenoid apart?

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Mainesail is the electrical wizard

 

Some voltage drop while cranking would be expected. As noted above, check that the battery terminals are clean.

 

Before dismantling the engine, I'd probably try a fresh cranking battery. Especially if the old one has more than 2 years on it

 

P

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Have you checked the battery for a bad cell? My diesel Jetta would not start well until I replaced the battery. Turned over just slow enough to not start. After replacement never a problem. Otherwise the starter looks like a suspect.

 

Posted at the same time as the previous post.

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What's the voltage on the battery when you're cranking? If it's low, then it's the battery. Just because the battery measures 13V when unloaded doesn't mean it's still good.

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It should not drop to 8 volts - that is your issue. Have been through this drill before on my 30 year old set up. 1. You need to check the battery - get it load tested, if its bad replace it. 2. Does no harm so clean all the connections - both positive and ground, including the main ground. Then if that does not solve the problem pull the starter and solenoid and have them checkout, and rebuilt as needed. Listed in order of expense - battery load test free, costs nothing to clean the connections. If the battery checks out, and the connections are clean, then the expensive part. You might find you end up replacing the battery and having the starter gone through - 8 volts will have heated it up "a lot" if you cranked it for any significant amount of time.

 

Good luck.

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I can't disagree with those shouting battery but..... fuel will not pump if tb e fuel shift off solenoid is in the off position. Loosen 1 or more injector lines and crank the motor. If fuel seeps or squirts it is a low voltage problem. If fuel does not seep or squirt while you are cranking the motor over your shut off solenoid is stuck. This test cost nothinges and is quick. When my solenoid died I replaced it with a common choke cable, pull to shut off, because the solenoid was $300 + .

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New battery is cheaper than the mechanic visit and there is no downside to owning a new battery. I hate Walmart but they do have a kick ass marine battery for under $100.

 

Big marine batteries bring over $20 at the scrap metal yard ... Way more than trade in core at stores and worth the trip if you do a lot of batteries...

 

Sometimes, On some sailboat diesels , cranking brings water in through the exhaust .

 

The tiniest pinhole in a hose will let air in the fuel line and kill your engine

 

Starters do crap out and lottsa places can check your starter for you

 

But

 

Step one is to try a kick ass battery.

 

There is a ton of advice in this thread about steps twenty three through sixty five . I hope you don't need to perform those strps

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Thanks, i've load tested the starting battery and it checks out fine. I also tried starting the engine with a house battery without success.

 

I'll check out the fuel line. However, since the voltage at the starter side of the solenoid drops by four volts when cranking, i do suspect there is not enough juice reaching the starter.

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Ah -- new info. I'll assume the battery is OK

 

Gouv mentioned water building up while cranking. That can happen because the engine pumps seawater coolant while cranking through the exhaust elbow which can fill up the water lift muffler.

 

In an extreme case, you can get seawater backing up through the exhaust valves into a cylinder which would lock the engine.

 

This can kill your engine.

 

At the very least, see if your water lift muffler is full. If so, I'd call for backup because you may need to remove the injectors and turn the engine over slowly after draining out the muffler and exhaust line.

 

P

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Above is intended as a caution if the engine will not turn over.

 

Assuming the muffler isn't flooded:

 

If it's turning over much more slowly than normal with a good battery, and if all electrical connections are clean, it almost has to be a starter issue. I'm not sure a little extra water in the muffler would create enough back pressure to slow starting.

 

For slow starter cranking, the Yanmar shop manual mirrors the above with 2 extra steps: 1. Is the engine oil the correct viscosity (which didn't change while you were sailing) and 2. Does engine turn when starter motor replaced?

 

Doesn't sound like a fuel issue.

 

P

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Also think about the battery cable to the starter motor. Hard to diagnose, and when this happened to me (with an old car) I replaced all of the expensive things first. I think you can use a jumper cable in lieu of the cable to test, or just pony up the $20-$30 for new and not worry about it.

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One reason the battery is weak because the owner has been cranking this motor. There may be other reasons in cables and connections. Those generally show signs. Slow charging, slow cranking , intermittent performance. This problem came suddenly. Logically one item stopped working suddenly. Starters don't generally nor battery connections. Shut off .olenoid do. The solenoid check I outlined earlier cost $0 and takes 2minutes. Now I am real curious.

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easy to diagnose a cable problem. starter solenoid problem. put the volt meter leads on each side of the suspect component and read the voltage during cranking. the meter will show the voltage drop for that component. wire and starter solenoid should not be more then about .5 volt

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