YSM 12 starts, then dies

[ggrizzard]

So as not to hijack the other fuel line thread, I'll start anew with a slightly different problem that has occured after I bled the line.


We had lots of water in the tank and through the filters.

So I removed the Racor primary, the engine mounted secondary, all fuel lines from the tank to the lift pump, cleaned them and installed new filters. I had the tank drained, cleaned and polished fuel returned to the tank. I bled the fuel line and confirmed good fuel going to the injector.

Engine now starts as normal, with only a count of three on the starter.
It then runs normally for a few seconds and then dies.

I've looked for fuel leaks to indicate if one of the various connections/seals is loose and so far haven't found any.

I think air is getting in the fuel line somewhere.

First question: Is an air leak likely to be after the Racor? The Racor bowl stays full.

If the fuel return line to the secondary filter got dinged, would that cause the problem?

Why would the engine repeatedly get enough fuel to start but then quit running?

Thanks for any insights you folks might have.

 

[seadaddler]

Try

Try bleeding it again,maybe some air still in the line.
You did turn all shutoff valves back on,was it running OK before you started changing any thing.
Could be sucking air some place.
Nick

 

[Ross]

Re: Try

It sounds like it is running out of fuel. An almost completely closed supply line will allow enough fuel through for a start but not for a run.Do you get a good flow of fuel when you crack the injector supply fitting when you bleed the air out?

 

[Tracy23758]

The dinged return line could be a suspect. I don't know that particular engine, but if the excess fuel can't get back to the tank quick enough it must go somewhere I asume, like an overflow from the fuel pump or fuel rack. If too much accumulates there may be a safety shutoff connected to the fuel pressure regulator. Just a shot in the dark from the top of my head. Air is probably still the culpurit, or two lines that have been mixed up somehow.

 

[druid]

I was thinking like Ross: running out of fuel. How about the "lift" pump - the low-pressure fuel pump intended to get the fuel from the tank to the engine. If the tank is maybe a BIT higher than the engine, gravity would supply enough fuel to start, but not to run.

druid

 

[Benny]

It still has air in the line. Bleed again. Hope you are using the engine electric starter to pump the fuel.

 

[Hermit Scott]

I have the same engine. I think Benny is right. There is still air in the line. I bled mine and couldn't figure out why it wouldn't start. I took the injector and injector pump out and took it to a diesel shop. A guy checked them and said they were fine, but that I probably just needed to bleed it right.
The amount of fuel that actually gets injected is more like a fog that a spray of fuel. So any air in the system seems to stop the flow of fuel.

I also tried running the engine by spraying WD-40 in the air intake to try to work the air out of the line. My thought was if I run it long enough it will pump the air out. Well it doesn't work that way. It has to be bled out.

 

[Ross]

Consider that most diesels consume about a cupful of fuel per horse power hour and run at 2500 plus rpm That isn't much fuel per stroke. A bubble of air will act as a spring and absorb the impulse from the injector pump. When you bleed the injectors crank the engine with the connection at the injector cracked until you get a perfectly clean fuel flow and then tighten it the engine should immediately fire on that cylinder. Do this with each cylinder. The bubbles involved are very small.

 

[higgs]

Fuel pump?

 

[ggrizzard]

Thanks for all the input guys.
I havent been over to try your suggestions yet, but after reading the above, a thought came to mind.
It is possible that since i can't see very well, I may have reversed the fuel lines at the secondary filter.
The gravity comment got me thinking that since the tank is higher than the filters, it might just fill the line enough to start the engine but then not be able to pull fuel after that. If I get my good 'readers' on and a bright light and a young helper tomorrow, I should be able to see. If it is the case...

I'll let you know.
Thanks, G.

 

[Hermit Scott]

"I may have reversed the fuel lines at the secondary filter."
That is unlikely since the return line to the filter is a rigid metal line. And the filter can only be mounted one way. You would have to seriously deform that return line to connect it to the other port.
I am 99% sure you just need to bleed the line again.
Edit: never mind that last statement. The fuel line from the tank and the line to the high pressure pump are on the same side. THAT is possible.

 

[Hermit Scott]

OK, I thought about it a bit. It MAY still run. If you switch those it should still run. You would just be runnning fuel through the filter backwards. If your fuel return line goes to that filter I think it mounts on top.

 

[ggrizzard]

And the Winners are... The "Bleed it again" crowd!

Lines were not reversed, and so I opened the bleed valve and gave the lift pump a few tries with the lever and no fuel came through.
Used the engine crank to bleed the line and after 6 turns, a steady stream of fuel came spewing out. After that the engine started and stayed running for as long as I wanted on three different tries. :dance:

Again, thanks to all of you who participated in this weeks quiz.
The winners can claim your prizes at slip 44... the sea chest has dozens of Columbia shirts, gallons of Pussers rum, and dubloons from Mel Fisher's museum!
Please line up calmly, the slip's finger isn't too wide.

 

[Ron20324]

And the Winners are... The "Bleed it again" crowd!

Ahhh... If people would just start with the basics.