JCB Sitemaster runs for 10 minutes, then starves for fuel

[cgarai]

Hi,

My 1991 JCB Sitemaster backhoe is having a fuel delivery problem. I can't tell if it is the fuel solenoid, the lift pump or the injector pump. If left alone for a day or two it will run for 10-15 minutes and then start to bog down and then stop. Sometimes manually operating the lift pump will get it started again, but it will have very little power and then die.

While manually operating the lift pump I can see returning to the tank via the "clear" return line, but I also see bubbles that don't stop with extended priming. It seems like I might be sucking air in somewhere, but that would have to be before the lift pump wouldn't it?

The filter is new. The solenoid and lift pumps are only a few years old.

Any help, as always, is much appreciated.

Thanks,

Chris

 

[davesl708]

Apply some air pressure to the tank and look for leaks that could be allowing air into the system.
Also, could the tank have sludge built up in it and blocking the line?

 

[cgarai]

I didn't think about pressurizing the tank. Thanks for that. The tank most likely has sludge in it, but when I remove the fuel line the fuel pours out.

 

[davesl708]

Check hose clamps and inspect fuel line for worn or cracked areas. It will not take much pressure to find a leak. A wet spot should show up quickly.

 

[Tx Jim]

Check fuel return line and fittings from IP to tank to be sure excess fuel is returning to tank & not blocked.

 

[GManBart]

That's a very common symptom of a failing lift pump on those engines, and that pump design is know to fail on a regular basis. The good thing is that it's an inexpensive part, and not hard to change.

I have heard that generic replacement pumps aren't as likely to last as long as factor OEM parts. I know that was true with the lift pump on the Perkins engine in my Massey. The factory pump failed with similar symptoms to what you're describing....I had to manually pump the lever to get the engine to start and run long enough to get it back in the barn. I replaced it with a generic pump and it was fine for a few months, and then that failed...it would run, but leaked fuel into the block. I replaced it with a factor OEM part and it's been fine since.