Fuel Problem

[Irv]

Got a diesel fuel problem that is intermitent. I have the M25XP 25HP Universal diesel. The engine can run sometimes for many hours when suddenly it slowly dies as if it was starved for fuel. I pumped out some fuel from the tank and it seemed OK. Put in new fuel filters, & fuel pump. Same problem occurs after period of time, the engine just slowly dies. After bleeding, the engine will run again, sometime for 2 to 3 hours, and then it will die again. This is driving me nuts. Hoping someone will reply who is a diesel fuel expert or had similar condition but thru logical diagnostic sequence was able to lick the problem.

 

[John Visser]

Air leak into fuel system

You could have a poor seal upstream of the lift pump that is admitting air into the fuel system. This is a very common cause of loss of power due to fuel problems. THe other most common cause is a bad injector. Engine quitting due to fuel problems is most often air in fuel system, or a clogged filter. Source: Troubleshooting Marine Diesels, Peter Compton.

 

[Allen]

Another Possibility

I read an article where this happened to a new boat owner. They traced the problem to a clogged fuel tank vent. Over time, a vaccuum would form in the tank that prevented delivery of fuel to the engine. After the engine rested for a period of time, air eventually relieved the vaccuum condition in the tank and the engine would perform normally. Try loosening the fuel fill cap a little & see if that helps. If so, you probably need to clean the vent line.

 

[Tom]

Fuel Pickup Tube Screen

Check if you have a screen covering the fuel pickup tube inside of the fuel tank. This small screen was intended to prevent debris from entering the fuel line from within the tank. Unfortunately, a clog at this point (sometimes algae in the fuel can cause the screen to clog) will cause occasional fuel starvation problems downstream of the fuel tank. As you have inline fuel filters, just remove the screen completely from the pickup tube.

 

[Rob R]

Fuel Tank

Warning - this comes from an A-4 owner (gas jockey), and I am aware of the differences between diesels and gas engines.However, I get a similar problem when I haven't cleaned out the tank in a few years. What happens is this - contaminants (mostly water) collect in the bottom of the tank, slowly, over time. When the water and sludge builds up enough, it eventually gets high enough in the tank to enter the pick up tube, and it slowly works its way to the engine - shutting it down for a few seconds.The odd thing is that the engine shuts down about 30 seconds after going through a particularly large wake. It seems the sudden and turbulent rocking stirs up the water and puts it into the fuel line, but it takes a while for it to get through the water-separating filter and make it into the carb.Fun huh? Just a thought.Good Luck -Rob