Yanmar 4JH5E stalls when starting

[Sailing Drummer]

Just started having this problem. I have a feeling it might be the fuel injection timing, but I'm not knowledgeable enough about diesels to know.

Here's what's going on. 2011 4JH5E with 2300 hrs. Regular timely inspection/replacement of Racor filter and engine fuel filter. The Racor is checked every day the engine runs. Filters not due for replacement for about another 150 hrs (Yanmar spec change every 250 hrs). The Racor hasn't had any dirt or water in it for about 3-4 filter changes. The 2000 hr service has not been done yet, and that includes checking the injection timing and injector spray pattern. I am planning on having that done when we get back to the Chesapeake, maybe 100-200 more engine hours - depends on if can sail outside or have to take the ICW north. After every time the engine runs I follow Yanmar shutdown procedures, rev in neutral, low to high 5 times then idle @ 1000 no load for 5 minutes.

When I attempt to start the engine it runs for about 5-10 seconds and then stalls, as if there's air in the fuel. Second attempt it doesn't start and I don't let it crank for more than 5 seconds. Those attempts are at the recommended 1000 rpm. Then I push the throttle so it's about 2000 rpm and it starts up right away. I pull it back to 1000 and it's fine. This started about 4-5 days ago, it hasn't been every time I start, but most times. The last time I bled the fuel was about 100 hrs ago.

So, any ideas what this might be? Could it be that the last time I bled it I didn't do a good job and now it's starting to show up? But why will it start at 2000 and not at 1000 rpm?

I'll be traveling the next few days so if anyone needs more info I might not reply right away.

Thanks. Larry

[alamoana]

Hi Larry, injection timing I believe does not drift in time. I believe it is an air leak. Go through your filters..good luck

[a64pilot]

Called loss of prime.
Seriously, try Googling “Diesel loss of prime” you’ll get all kinds of hits, read to see if it sounds familiar, and of course some troubleshooting steps.
It amounts to air getting into the system after shutdown, and is a phenomenon that has been around as long as Diesels have.

On my truck Diesel, a 6.6L Duramax, it was a loose bleed screw on the filter, it was an intermittent thing for a month or longer then one day it just would not start, that was when I got to digging into it.

[Bean Counter]

This happened on our starboard engine. It took quite a while to find the culprit, it was a curly piece of aluminum material that was lodged in the elbow connector of the primary fuel filter. It did not completely close off the supply but caused all the same issues you mention. Turns out it was a swarf material from when they drilled the holes in the alloy tanks for the fittings. Same issues have been found in fresh water supply where plastic drilled tanks have had swarf collect in filters and housing ports.

[DeepFrz]

Try starting at the first start with the throttle at about 1500-2000 and see what happens.

[Sailing Drummer]

I hope it's not something lodged in the hose. That might be tough to find without replacing all the hoses.

Loss of prime looks very similar to what I'm experiencing. I'll have to check all the fittings to make sure they are tight. And look in the Racor to make sure it's full.

I'll try starting tomorrow at a higher rpm but not sure what that would tell me about the "why" it's doing it.

Thanks for the tips!

[AAC1956]

On my etap 32s after six years of light weekender use I had similar problem. They started by checking injector, timings, etc.
It was a fully cloggeg exhaust pipe. Replaced and it went back to perfect.
Ps 18kw diesel twin cilinder volvo

[Sailing Drummer]

Don't think my exhaust is clogged. Always has plenty of water coming out. But I will take another/closer look to see if it looks like it's changed.

Tried starting this morning with revs up. Same exact issue - started then stopped, then wouldn't start, then started with the revs up. Also this morning I gave the pump a little more time (but still same issue). Tomorrow I'll get to Vero and be on a mooring in a more protected area. We've been bouncing all over the place with this weather. I'll bleed about a quart or more and make sure there are no bubbles. And I'll check the Racor, drain it and refill it (before I bleed the fuel). I think it looks like the answer is loss of prime. And I have to find out where the leak is.

Larry

[a64pilot]

Usually, or at least every time I’ve experienced it, a blockage in the fuel line results in a drop in RPM or even engine shutting down at high power, reason is of course it can’t flow the fuel required to run at high power.

[01kiwijohn]

Drummer, somewhere, you have a small air leak. It could also be air trapped in the system, but I doubt it as it runs ok once you do get it running.

[Presscars]

Hi I had the same problem or symptoms. Turned out to be the electric fuel lift pump had stopped operating.

[a64pilot]

Originally Posted by Presscars

Hi I had the same problem or symptoms. Turned out to be the electric fuel lift pump had stopped operating.

Happened to me too on a K3500 6.2L truck.
I didn’t even know the thing had an electric lift pump, it was down in the frame rail.

[Moontide]

Try leaving the key on for 30-60 seconds before turning over the engine. Will give the electric fuel pump time to push any air through the system.


Bill

[whosnext]

It will probably be the fuel presure pump, a diesel has a fuel presure pomp, normally when air is in the line the fuel presure pump is broken.


You sometimes only notice this issue after a long time not turning on your motor, or when you are at heavy sea so big waves so air is flowing in your diesel fuel lines and stops the "normal vacuum" you engine will produce when started.


So check this fuel presure pump

[Bean Counter]

Buy 50ft of diesel fuel hose and a couple of joiners and T's (it will come in handy later if you ever need to run both engines off one tank - includes return) Run the hose from one tank to the other motor - this will identify where the issue lies - in the lines or at the motor.