Crusader losing RPM

[summersanity]

I have a 2001 8.1 crusader engine. After running for about two hours I lose RPMs on one of my engines. I have replaced the fuel cell filter and cleaned the pancake filter. I have also connected a compressor to the fuel vent and blew it out. This is very consistent. Always happens on longer trips. On other note, if I fill the tanks, as I always do when traveling, it always seems like it happens when the fuel drops to 1\2 a tank. Could just be a coincidence. Any Ideas?

 

[Bondo]

Ayuh,.... Welcome Aboard,..... My 1st thought is a crack in the tank's diptube might be allowin' air into the system,.....

 

[FunInDuhSun]

Bondo has a good idea (as always).
Does your boat have fuel crossover valves? If so, try feeding both engines from one tank, then the other. It may help identify where the problem lies.

 

[summersanity]

no cross over tanks. I wish!

 

[Bondo]

Ayuh,.... Then run that motor on a remote tank of fresh clean gas hooked directly to the fuel filter,......

 

[summersanity]

If the RPMs start to fall I can shut the engine down for an hour then it will run fine again for two hours before failing again.

 

[Bondo]

Ayuh,..... So run the test I stated above,....

If it runs flawlessly, yer tank is the problem,.....

 

[summersanity]

ok, I hope I found the problem. Easy fix. I replaced the original (15 years old) pancake filter and ran the boat for 3 hours without an issue. I hope this is the end of my problem.