Starts, Idles, then Dies + Stalls on Takeoff - YM 1GM10

[nickj]

Hi all,

I have a curious problem I can't seem to be able to diagnose... Just recently I installed a Racor fuel filter, new fuel lines, and a new injector in my Yanmar 1GM10 - It was new in 1999 and has seen about 5 years use - Everything was working really well, until the other day. The engine starts right up, but only on full throttle, at which point it idles for about 10 seconds, and then dies. The only way to get it to start, is to leave the engine in full throttle, and hold the starter down, and let the idling engine keep going with the starter motor keeping it in motion. This is not a good way to start it, but if you do this three or four times, the engine eventually warms up, and starts completely, revs out, and behaves in neutral as it should. However... Upon putting the engine into forward or reverse, it engages, and then dies under load. In neutral it also seems to respond slowly to increasing throttle. As if their were 'lag' ...

To me this seems like a fuel starvation issue. But what perplexes me about that idea, is why the engine would eventually start and throttle correctly in neutral after it is warm at all - I would have thought if it were fuel starvation, the sympton would persisit regardless of how warm the engine were - Also, right now I'm in a fairly hot environment (Hawaii), so it is not a cold starting problem.

Has anyone seen this issue before?

Thanks, Nick

Bigoceans | Tiny Boat
solo from europe->australia

[Chief Engineer]

If you installed a new racor fuel filter assembly, make sure the "in: side comes from the tank and the "out" side goes to the engine.

Otherwise, if you have no return line to the tank, the secondary filter is getting filled with air.

Bleed Bleed Bleed

[nickj]

I thought it was the Racor, so bypassed it... But the problem persists... I also do have a return line... Any other thoughts?

[mesquaukee]

Originally Posted by nickj

Hi all,

The only way to get it to start, is to leave the engine in full throttle, and hold the starter down, and let the idling engine keep going with the starter motor keeping it in motion.
Upon putting the engine into forward or reverse, it engages, and then dies under load. In neutral it also seems to respond slowly to increasing throttle. As if their were 'lag

That sounds like a fuel imjection pump problem. Some piece of gunk found its way into it.

[nickj]

Originally Posted by mesquaukee

That sounds like a fuel imjection pump problem. Some piece of gunk found its way into it.

That could be it... I had some REALLY dirty fuel get in there, which is why I installed the Racor... Is there any way I can clean it myself, or it it a job for a professional?

[mesquaukee]

Originally Posted by nickj

That could be it... I had some REALLY dirty fuel get in there, which is why I installed the Racor... Is there any way I can clean it myself, or it it a job for a professional?

If you need to ask you need a pro. It is not something you would want to to tinker with!

[captain58sailin]

Have you looked at the condition of the primary filter on the engine?

[nickj]

Originally Posted by captain58sailin

Have you looked at the condition of the primary filter on the engine?

Yes, the primary filter is brand new, as is the Racor...

Regarding the injector pump - Are there any definitive tests I can do myself to see if that's the source of the issue? I have pulled the injector and watched the spray pattern, which appears correct, but... As you can tell, I'm no diesel mechanic.

Thanks, Nick

[Cheechako]

Is it possible one of your new fuel lines is sucking some air? are any of them flared copper? If so you may have to really tighten them hard.

[mesquaukee]

Fuel shut off. Do you have a manual stop control (pull push) on your engine or is it electrical. If electrical there is a solenoid valve on the fuel line. It should be mounted or built into the back of the fuel injection pump. Check them, make sure they fully open.
Air Filter take it off and see if there is a difference.
Bleed all the fuel lines If you see any bubbles at all it is as Cheechako suggests above. Tiny bubbles are messing with the injectors. A few little bubbles will not neccessarily shut down your engine. At high speed a few very small bubbles will pass through the system.
Lift pump Maybe it is only dribbling fuel to the injection pump. Check for good flow.
Injection Pump That is all that is left. This is one item that only a pro should work on.

[Chief Engineer]

You have not said if you have re-bled the engine.

Have you connected the Racor with the flow in the proper direction?

Bleed from the Racor....to the secnodary filter on the engine......there should be a bleeder screw on the injection pump......crack the nut on the injector.......
When you are bleeding the injector, open the throttle wide......there must be no bubbles at all......Do you have someone available to crank the engine while you observe?

The other thing is that you might have a cable problem......

If you have a separate stop lever, make sure it is in the "run" position on the engine.

As an aside, you said the engine ran un neutral but when you put it in gear it stopped. Something on the shaft?

[Dune]

I would bleed again and again. Changing fuel lines introduces a lot of air into a fuel system and an air lock could be your problem. I put my money on air in the system. You can pressure the tank and cycle fuel until it is pure. Be careful that you don't put too much pressure on the tank. 2-3 lbs should be more than enough. Another advantage to pressure is you may see a wet spot develop in the system signaling a leak. Also, check EVERY connection that you touched (and it would not hurt to check the ones you didn't) to make sure they are seated properly. If the engine ran well before you did the changeover, I would doubt that the injectors or pump are at fault.

[s/v Jedi]

I will add my voice but be warned I am not a mechanic so these remarks are from experience ;-)

When you get it to run in neutral, I would check for black smoke. Or any smoke really. Also, it sounds like the engine can't take a load so it is either fuel or breathing so I would first check air inlet and exhaust system (no valves in exhaust? is the exhaust gas coming out of the thru-hull or is it displacing the oxygen in the engineroom? etc.)
For fuel: good time to decide to invest in a small Walbro fuel pump that's installed before the primary filters so you can operate in a little pressure instead of vacuum. Leaks will show by some diesel drip instead of air in the lines.

cheers,
Nick.

[lmckay]

I have a 2GM20FC engine and had almost the same problem.
Started the engine, ran for about 3-5 minutes and then died.
Leave it alone for a minute and it started again, ran and died.

It turned out to be air in the fuel line trapped at the engine mounted fuel filter.
I thought air in the lines would stop the engine dead, but that's not true.

I agree with the others, bleed your system.

PS. You can down load the service manual for your engine here:
Cascade Engine Center | Diesel Engines | Yanmar Manuals

It has the disassembly & test procedures for the entire engine.

[Chief Engineer]

Well we haven't heard from you in two days......whazzupppp????