Yanmar making weird sound

[Lisak]

Hi all, I’m reaching out here to see if anyone with more Diesel engine experience could help us diagnose an engine sound. We have a an old Yanmar that was running fine for about 20 minutes until she shut off without any warning. We thought it was a fuel issue so we changed the first filter and bled the lines. She runs for about 1 minute fine, makes this tsk tsk tsk sound (at the end of and shuts off.

Video here:

https://imgur.com/a/0CcRrVi

Any advice would be greatly appreciated!! We are currently in remote area in the Bahamas with not many options but to fix this ourselves! Thanks so much.

 

[trevbouy]

Does it start again and repeat?

 

[Lisak]

Does it start again and repeat?

Yes it does start up for about a minute sometimes less and then shuts off

 

[xeitosaphil]

Could be dirty air filter, blocked fuel tank vent, dirty filter from the tank ( mine has two) one from the tank, second on the engine). Sounds like it's only just using all the fuel in the injector pump.
Could also be s lift pump problem?
Best if luck with it.

 

[trevbouy]

I asked because the sound is just like a fuel starved engine where each cylinder shuts down over a second or so. The tsk tsk is each cylinder that has no fuel being driven round by others as each shuts down.
Is the shut off ok? Has symptoms of a moving fuel clog.

 

[penberth3]

I asked because the sound is just like a fuel starved engine where each cylinder shuts down over a second or so. The tsk tsk is each cylinder that has no fuel being driven round by others as each shuts down.
Is the shut off ok? Has symptoms of a moving fuel clog.

That sounds reasonable. I'd also check the stop control is fully returned to the "run" position.

 

[RichardS]

Definitely fuel starvation. Could be lots of causes but first check that the tank vent is clear or run it with the filler cap removed.

Richard

 

[Lisak]

Thank you all for your suggestions. Based on many answers here and a call to a friend (bus diesel mechanic lol) we are agree it’s a fuel starvation issue. After verifying fuel is flowing fine to the filters, changing all the filters, bleeding the line we believe we narrowed it down to the fuel injectors. We made one turn to loose the hose at the cylinder side, started the engine and found only 2/3 injectors seem to be supplying fuel. We unattached the suspecting faulty hose and blew through it to clear any suspecting clogs.

Could it be an issue with the pump or no since 2/3 of the hoses are pushing fuel along fine? I’m starting to think if there is a clog there’s really only one spot it could be... between/in the fuel pump and the beginning of the injector hose.

So with all that being said anyone have any tips before we start tearing into this fuel pump? Or anything else we can try?

 

[emnick]

Have you checked the fuel pick up in the tank? I had a blockage once that did similar. I changed all filters and still had problem. It turned out to be a blockage on the pick up strainer / filter............it then needed to have the tank cleaned out but been fine ever since. can you "toggle" the lift pump (disconnected) to secondary filter?

 

[Bilgediver]

Maybe your lift pump has a filter. Some do! If your lift pump has a screw in the top of the dome cover then remove the dome and check the small plastic filter is clean . It is easily cleaned and put back. The existing cover joint should be ok if you remove the dome carefully.

Someone in our marina spent weeks with a similar problem.

 

[trevbouy]

Hmm it's strange how it fully runs on all cylinders for a measured amount of time/fuel then starves each injector and shuts down.

I would look at lift pump and also for an air leak being introduced from filters to lift pump. It's obviously reaching injector pump to be distributed to injectors then pump is being starved of fuel causing shutdown.

 

[Graham376]

If the fuel line allows, see if it runs from a can of clean fuel, may be debris in the tank or bug blocking it.

 

[Blueboatman]

Turn water inlet off and ...
Put the three decompressors down

Then lift each one in turn and crank the starter
And thus verify that each cylinder is firing when you crank . 1, check , 2, check, 3 check..
Turn water inlet back on

Personally I like to disconnect the fuel pipe from the fuel tank where it goes into the primary filter/separator and verify a good 4l worth of clear fuel is pouring at an acceptable rate into a clear plastic jug ..

After that you might check the secondary filter..

Your engine sounds pretty ‘normal’ when running, to me! ( 3gm30f here )

 

[Bilgediver]

Hmm it's strange how it fully runs on all cylinders for a measured amount of time/fuel then starves each injector and shuts down.

This is exactly what happened with the engine here . Because the lift pump is not able to deliver sufficient to the injector pumps they pump until there is zero pressure from the the lift pump and then the cylinders cut out . The pressure at the injector pump restores when the engine is stopped because the lift pump is still running as the engine slows and stops with a zero fuel demand ready for the next start and then same again.

 

[vas]

+1 on lift pump + pickup.
WARNING, unless you've established that pickup, filter(s) pipes are clean DO NOT play with the injector pump!
highly unlikely it is it, higly likely you;ll mess something there removing and refiting (not that straight forward with the governor arm having to be in certain mid position for the pump to make it off the engine.
Had all sorts of issues with my generator 2GMF, turned out that lift pump was slightly leaking air in (thankfully no fuel in sump) and the pipe from lift to injector pump was also leaking minute quantities of air in the circuit making it difficult to start. Fitted an el. lift pump, tigthened a circlip, all fine. Took me over a year of testing different things though

Best test is to bypass lift pump, get a canister of clean diesel with a short hose in it on the cabin floor and start from there, inj pump will happily suck from half a meter, no probs, if it works fine for 5-10 mins suspect lift or pickup pipe debris.

V.

 

[Lisak]

Just wanted to post an update to anyone that might stumble upon this in the future and everyone who offered advice. We got it working fine and thankfully it was indeed an easy fix.

The fix: we pumped air through the fuel lines from the hose connected to the racor filter back to the tanks (we have two 50 gal tanks). We heard bubbles come through fine to one tank and the second tank took some pumping to unclog whatever clogged the hose to that fuel tank. Now we need to prevent that from happening again

Thanks all!

 

[emnick]

Just wanted to post an update to anyone that might stumble upon this in the future and everyone who offered advice. We got it working fine and thankfully it was indeed an easy fix.

The fix: we pumped air through the fuel lines from the hose connected to the racor filter back to the tanks (we have two 50 gal tanks). We heard bubbles come through fine to one tank and the second tank took some pumping to unclog whatever clogged the hose to that fuel tank. Now we need to prevent that from happening again

Thanks all!

Possible Diesel bug then, you will need to get into the tank to clean it, there will be sludge behind the baffles etc.........glad you got sorted