I bought a non running john deere 350B track loader. When i checked for fuel , i found good lift pump pressure at the injection pump and i have fuel returnig from the injectors. I hot wired the fuel shut off switch and that is working. I cracked the injector lines on the pump and no fuel is there. I also pulled two plugs out of the side of the pump and there is no fuel inside of the pump. I don't understand how i can be getting fuel from the return line. Can it be back feeding out of the pump thru the return line ? I did'nt crack all of the injection lines. Can the fuel only be coming out of one line on the pump ? Anyone have any ideas on this ?
The inj pump is just that.. a pump.. It has pistons, plungers and springs inside.. so yes.. u can have fuel going in, and fuel coming out and nothing else, if the pistons, plungers and springs are stuck. This is my area of knowledge.. I was gonna say expertise but… Anyway, remove all the fittings off the top cover.. ALL OF THEM. If done correctly, u should be looking at an open hole in the cover… now loosen as many steel lines AT THE INJECTORS as u can get to, just a turn or 2.. enough to let any trapped air out.. Pull the throttle to wide open and give’r a spin.. DONT burn up the starter.. a couple of 7 second count on the starter will tell u if your pump is pumping..(injectors are dripping) If that doesn’t work.. remove the top cover..(3 screws & washers).. Do a Google search on Stanadyne metering valve to get an idea of what your looking for/at.. MAKE SURE ITS FREE.. REAL FREE.. u should be able to flick it with your finger and it return on it’s own.. How about the QUALITY AND QUANTITY OF FUEL your trying to start it on.?? U could bypass the tank.. just put a rubber hose on the supply pump where it would “normally” suck from the tank and get a 5 gallon container of fresh diesel fuel..& put ur hose in it.. Be careful taking the screws outta the top cover.. don’t put to much force on them cuz they will snap.. Good luck and feel free to reach out in a prvt msg if need be..
Assuming that it is the same Stanadyne pump as on a 450, the simplest way is to send the pump out to a good rebuilder. I watched all the videos, and very carefully disassembled mine, documenting every step. Wound up sending it out for a rebuild. If you have pressure at the injector pump input and nothing at the injectors, send it out!