I know this isn't exactly stationary engine territory, but I'm hoping somebody here may have experience or tips to try.
My neighbour bought a JCB 3CX last month (perkins 4.236 engine with CAV DPA3241F350 pump), and it had been running fine until he ran out of fuel at the start of the week. He put 4 gallon of diesel in it, and I bled it up for him. He fuelled it up, and it ran fine for about an hour before spluttering to a halt again, and I've been unable to get it running again since.
Fitted a new fuel filter as the old one was full of dirt. Kept getting seemingly random pockets of air from the top bleed screw on the pump - we'd bleed up to the pump, then after several attempts at getting fuel to the injectors, check the pump again and get more air. After checking to see where fuel was going/not going, discovered the small hole in the bleed pipe banjo bolt on the filter head was choked. Cleared that out and it stopped the random air in the pump. Still wouldn't bleed to the injectors, so after more pipe disconnecting, discovered that no fuel was coming out the pump bleed screws with only the inlet pipe connected (the fuel that came out previsouly was obviously coming in via the pump return pipe as the entire fuel system is slightly pressurised due to the only return to the tank being via the bleed banjo/injector leak of pipes). Dismantled the regulator on the back of the pump and found the pump inlet filter was choked. Cleaned it which meant fuel could get into the pump the right way, and plenty fuel now comes out the bleed screws when opened (I still have the pump return pipe of).
But it still refuses to pump anything upto the injectors. When you first start cranking the engine, a couple small bubbles come out the injector pipes, but that's it. One thing I have noticed, is there is minimal fuel coming out the pump return port. Does anybody know if fuel should be able to flow freely through the pump?
I've now come to the conclusion the pump is most likely needing removed and overhauled, but is there anything obvious I've missed? Or any other tricks I can try to nurse it back into life?