I can’t get the marine diesel engine (3 cylinder Westerbeke/Universal 25 HP) on my sailboat to keep running. When cold, it starts ok and runs for about 1 – 2 minutes, then sputters and shuts off. It runs a little longer at low RPM than high RPM. After this short run and sputtering off, the engine won’t start again, it just sputters with the assistance of the starter. After the engine has sat a while, 20 minutes or so, the same thing happens again. The starter cranks the engine over just fine. I’ve thoroughly checked the fuel system and it seems to work ok. I have done the following:
Replaced the Raycor prefilter coming out of the fuel tank (the fuel looked clean but I replaced it anyway)
Replaced the fuel lift pump (the “old” one was only about 3 years old, looked like new and seemed to pump just fine)
When the glow plug button is pressed, one can hear the fuel lift pump working, just like on the original.
Replaced the fuel filter between the fuel lift pump and the injector pump
Bled the air (the system is supposed to be self bleeding, but I hot wired the lifter pump and manually bled anyway at the fuel filter between the lift pump and injector pump)
Pulled off lines between injector pump and injectors and observed fuel coming out of injector pump, no air bubbles.
Opened up the injectors and cleaned the jets – they were a little sooty, but not overly so.
I hot wired the lifter pump and heard fuel flowing through the overflow lines at the top of the injectors and dropping back into the fuel tank, as normal.
I have a vacuum gage between the Raycor filter and the fuel lift pump, and the gage shows 0 psi, no problem there.
What is the problem? The engine was very reliable till the onset of this problem from one outing to the next. I can’t think of ANYTHING we did between outings that should cause this. Is there a thermostat or something else somewhere that is shutting down the system? If so, what is it and where is it on this engine? The engine runs for such a short time that it is still cold to the touch. HELP!!!
I would say that it sounds like you are loosing the prime due to one of two things, either you are getting air into the system, which could be something as simple as an o-ring on a fitting or as complicated as something going on in the fuel pump itself, and without hearing it run it would be hard to tell from here. The other possibility is that you are somehow pulling a vacuum on the tank, if you have recently changed the filler cap, or something has blocked the vent that allows the air to enter the tank as the fuel is pulled out.
This just sounds like a fuel issue where you are loosing prime some way, and I would hope that it is possibly air getting into the system somewhere easy to fix, or something simple like a stopped up vent or fuel lines, because if not it may be tough to figure out without checking pressure at the lines.
I stuck the technical manual and the operators manual on here for you, just in case you do not have them already, which I am sure you do, but maybe someone else will read this and want them.