M25XPB fuel starvation

[burns3c]

I need help from anyone that is familiar with these engines. I was running the motor after it had sat for 6-8 months straight (I believe I put stabilizer and biocide in the tank at the last fill-up, but that was probably last fall). Anyway, it started right up after the long off-season, and I was running the motor at idle for about 20 minutes with no issues, when all of a sudden it sputtered and died. Since then, when you start the motor it fires right up, runs for almost exactly 40 seconds, then dies, every time. I figured air in the fuel system somewhere. So I bled it out, first at the spin-on fuel filter, then the injection pump, then the injectors themselves. No change. I changed the fuel filter and racor. No change. I removed the injection pump and cleaned it as best I could with seafoam. No change. So I’m basically stumped here. Tomorrow I’m going to unhook the fuel tank from the lift pump and run a temporary fuel line into a jerry can full of fresh diesel to eliminate the possibility of upstream issues and fuel contamination/deterioration. But I’m pretty much out of ideas. Any advice? Thanks

 

[jssailem]

Yes the symptom you describe sounds like fuel starvation.

Based on that premise, I would start at the tank and assure that there is nothing in the system of hoses that could cause this issue.

1. The pickup tube. Some boat builders install a screen to filter any debris in the tank. Lift the tank dip hose, and clean/remove the screen so that fuel can flow freely from tank into hose
2. Next hose from tank to first filter. Assure hose is clear of any debris. Diesel fuel can degrade. A sticky gelatin like substance (Asphaltines) can form and get sucked up into the hose. Clogs can happen along a hose or at connections like the entry into a fuel filter. Check to assure no debris is in the line
3. Fuel check valves. Some off engine fuel filters have a small check installed. It stops fuel from draining back into the tank. @Stu Jackson has discovered and written about it here on SBO. Assure it is not stuck closed
4. You installed clean filters. I had this issue. Here is an image of a dirty filter that caused my engine to stop.
   
   
5. Then there is the filter on the engine
6. Finally the fuel lines from the engine filter to the injectors

With the fuel lines clear try the engine again and report back.

This can be a messy job but is the best way to be sure that fuel can flow to your engine and go Vrroom.