Diesel Engine Cutting Out

[ausnp84]

Hey guys,

Need some help with my starboard engine.

Issue started with it hunting, then cutting out. Marine engineer said it was water in the diesel so his solution was to run fuel in / return lines to a jerry can

Reconnected engine, filled up the tank with fresh diesel and it worked for 3hrs then started hunting and cut out. We could see air coming into the racor so tightened it all up and it literally worked for 3hrs again and cut out. Annoying to say the least.

Today I swapped the hosing to the racor and engine, swapped out the racor filter and seals, primed the engine and after a few attempts, got it running for 30sec/1min then it bogged and cut.

Now the engine starts every second key turn and runs for 30sec/1 min, bogs and cuts.

Thoughts? I’m going to swap the fuel filter, but am thinking it could be a lift pump issue and the engine only getting the fuel between itself and the lift pump (generated during the ignition process), hence the short run each time.

Anyone else have a similar issue? Engine is a Lombardini LDW 1204SD for reference.

N

[Cheechako]

Possible the vent line is clogged? Little insects build nests in the vent outlet on the hull, so it creates a vacuum when the engine runs a bit.

[Bean Counter]

Had a similar issue with a Yanmar, nothing to do with the engine, a small piece of debris had lodged itself in the elbow fuel inlet on the fuel water separator housing (primary filter) and it caused variable effect, sometimes no engine run at all, then would quit after 20 minutes or when engine was run up a few more revs. So it had not completely blocked the inlet.


We discovered it when engine had shut down, I disconnected the fuel hose after the fuel pump to observe the fuel squirting out, it was not a strong, just a fast dribble really, compared to the other engine. I swapped over fuel pumps and had the same result, so that led to the tracing of the fuel partial blockage.

[sailorchic34]

Did you change out the on engine fuel filter?

[ausnp84]

Originally Posted by sailorchic34

Did you change out the on engine fuel filter?

That’s my next task. I’ll check the vent line as well, and will add some Hylomar (gasket goo) to the lift pump in/out just to make sure that’s not an issue either.

Anything else it could be?

N

[NYSail]

Pull the back brake hose off the racor and blow back to the tank. Some fuel tanks have screens on the pickup that get clogged. You will feel and hear.... also as mentioned check vent.

Good luck

Greg

[SVRocinante]

Had our Yanmar do the same thing as we where entering a channel; engine just quit!
Started up again, ran for a few, then quite again. Started up again, etc.

Changed fuel filters, fuel/water seperator, checked hoses, etc.

For us, the issue turned out to be the Fuel/water seperator itself. It was sucking air, but I couldn’t find the spot; replaced the filter, o-rings, etc... no luck.

Pulled entire unit off and replaced it with a new one; problem solved... it’s been over a year now; no more fuel issues!

[Excalibur5]

Our Yanmar did the same thing whenever the main tank was below 30%. In our case it was the top of the racor housing. Some of the plastic parts were old and brittle and we're letting air I to the fuel lines. A new filter solved the problem.

[aquafacts]

Follow the air bubble trail ! You must find where the air is getting into your system - either its the Racor or something between it and the tank ! Check the fuel shut off tap at the tank, (have run into several that were the source of the air !) Could even be a cracked fuel pick up to tank bottom. ( I assuming the primary filter has been changed already)

[Cheechako]

Originally Posted by NYSail

Pull the back brake hose off the racor and blow back to the tank. Some fuel tanks have screens on the pickup that get clogged. You will feel and hear.... also as mentioned check vent.

Good luck

Greg

Good thought.

[01kiwijohn]

if you could see air ingress into the Racor, that's where I'd start. how about getting a piece of hose to run from the tank to the input side of the secondary filter, then you'll know for sure if you've got an air leak in the line or fittings.

[NYSail]

and its not uncommon for the pick-up tube inside the tank to fail........ Many places to look but start simple

[Chuck34]

Easiest way to check if your vent is clogged...take the cap off the fuel fill and see if the engine runs better.

I'll throw this out there fwiw...I had a lot of problems with my genset cutting out. Mechanic tried several things that didn't work. Then he just happened to mention there was a check valve in the fuel line at the fuel tank. We changed that and all was good. Until that day, I had never heard of a check valve in a fuel line

[Cpt Mark]

In order of the top 3 reasons why people have issues with their Diesel engine.

1. Fuel
2. Fuel
3. Fuel

So it runs for a period of time and quits. Is the Racor full when it. quits, yes/no. If not (probably) then you need to figure out why. In very few cases will there be a block in the line. It's either going to be an air leak or as you guessed earlier, the mechanical lift pump which based on my experience with those symptoms is likely the cause.

If the racor is full then check your fuel flow on the output side of the Racor prior to the mechanical pump. Just crack the fitting and see if solid fuel comes out or fuel with bubbles or no fuel. Depending what you find there tells you what to look for. Have solid fuel there? Then move to the output side of the mechanical fuel pump and repeat. If not there then go to the output side of the injector pump.

Racor. Real Racor's you can see through the clear bowl to look for water in the racor. If you see some (it's obvious as water/fuel do not mix) then drain the water out. If you have water in your main tank the Racor should stop it from getting to the engine. Lastly, if you are completely filled with water in the Racor there is a ball valve (kind of like a shop vac when used wet) which will push up and cut off the flow so water doesn't get into the fuel system past the Racor.

[ausnp84]

Ok, thanks all.

More troubleshooting today - I completely drained and refilled the racor, primed the system and had the same issue happen. Have finally got part details from Lombardini for the lift pump as even tho there is fuel in the line AFTER thr lift pump, previous experience has taught me they can be difficult things. Also have new fuel filters on order for both engines and will test the fuel vent theory tomorrow.

So....
1.) Any potential water has been drained from the system
2.) Racor filter and seals have been replaced
3.) Hosing to racor and from racor to lift pump has all been swapped out

Next:
4.) Engine fuel filter to be replaced
5.) Fuel vent line to be checked and tested
6.) Fuel return line to be checked and tested
7.) Lift pump to be replaced

Update to follow!

N