This has been an ongoing issue. Its a simple issue if I could just find it!!
the engine runs beautifully for a long tine. Sometimes an hour or even more before it starts these symptoms. The symptoms are of air in the fuel line. That is a drop in rpm followed shortly by a recovery. It is a turning a generator and so the governor is fixed to 3600rpm and not adjustable. I replaced the primary fuel filter unit and filter (the entire thing) because I just could not get the old unit to stop leaking at the o-ring. I have currently got the secondary fuel filter bypassed to eliminate that as a suspect. Fuel has been bled At the bleed nut until air bubbles are gone. All fuel supply hoses have been replaced. (The only remaining hose is the piece that runs from the diesel tank to the facet electric fuel pump). Ive replaced the facet fuel pump as well.
I also watched the fuel cutoff solenoid during the rpm drop and it is not the cause (So not electrical induced)
The only remaining suspects would be the injector, the fuel lift pump (but it works when manually toggled-so unlikely) or the diesell tank pickup?
The diesel tank that supplies the engine is shared with my main boat engine. A 100hp yanmar and it runs just fine. So eliminated fuel quality/contamination as a suspect. This would also eliminate a supply tank bleed issue. Any ideas before I toss it out and use it as a seabed weight! Feeling quite frustrated.
I believe that you are on the right track with a fuel issue but I have some questions for you first.
1) is the fuel supply line a shared one with the main engine?
2) how far is this engine from the fuel tank?
3) what kind if air filter is used?
4) what temperature is the coolant when this is happening?
2) im going to guess around a 3-4m run of fuel line from tank to electric fuel pump
3) Im using the part number211-62950 air filter (beta spec)( recently installed)
4) I dont have a coolant gauge but raises an interesting question, how could the coolant temperature increasing cause this? (because the issue isnt necessarily prevalent until the engine heats up)
There is one thing that jumps out at me. You state that the generator has separate fuel line and pickup from main engine.
If this is correct I suggest that you provide a separate pick up at the tank with it's own pick up tube in the tank and then you will have solved the problem. You cannot use one pick up for the main engine and the generator. It never works successfully.
What is the WOC number of the genset?
Have fun, Stanley
-- Edited by Stanley on Friday 21st of August 2020 09:14:13 AM
Is it possible that one of the fuel lines is starting to de-laminate or collapse and causes a part time blockage?
The hose that I would suspect first is the one between the tank and Facet 12V pump.
I am reviving this year old issue because I still have not got to the bottom of it! I recently replaced the fuel feed line from the tank to the facet fuel pump but I still have the same issues.
To recap, the engine runs beautifully for a time period of just over 2 hours (almost exactly everytime) and then it cuts out but before it comes to a stop, it catches itself and recovers. This episode repeats itself from thereon every 10 minutes or so. I have just ordered new fuel injectors and a fuel lift pump. Failing these resolving the issues, the ONLY piece of the puzzle that would not have been replaced is the fuel injector pump itself. Any other ideas out there?
Once again, thanks Stanley for you reply. I appreciate your time. I had not suspected valve clearances and so will do these as soon as I get a new gasket. It has been suggested by an engineer friend of mine that another area of suspicion could be the hard fuel pipes that run from the IP to the injectors, in that these develop a fine crack which opens up as the engine heats up. Sounds very plausible too but will start with the valve clearances.
Yesterday I checked the valve clearances which were spot on, bonnet replaced with a new gasket.
Also installed 2 brand new fuel injectors with new copper washers.
Replaced all fuel hard lines with new ones. All parts supplied by beta marine.
Once again, engine ran fine after bleeding until around 3 hours when the rpm drops from its set 3000rpm but it self recovers just before stalling and carries on running seemingly normal, repeating this process every 10-15 minutes.
Any chance the electrical wiring or a bad earth could be an issue? Im plucking at straws because the only parts not replaced are the lift pump and the injection pump. So much time and money invested, its a hard one to just give up on.
