Hello all. Been a lurker on here for a while and now I have an issue. The dozer is a 1985 Deere 750. Serial number T00750G389082. Was running great and it started to act up so thinking it might be running out of fuel I shut it right down. I checked and still had plenty of fuel so started checking things out. Still had fuel to the pump and I could hear the audible clicking of the shut off solenoid so after going through the fuel system from the lift pump to injection pump and everything seemed to be fine. Pulled the top off the IP and turns out the solenoid was clicking but not moving. Took it to the shop and bench tested it and wouldn't work. Installed new solenoid and it works as it should. Now I can't get the thing to start. I've got fuel to the IP and can't get it to the injectors. When I take the pressure relief valve off the top of the IP for the return line, the IP doesn't seem to build any pressure inside. When I loosened the supply line from the IP pump the cone turned a little bit. Was wondering if the screen/filter inside that cone could be plugged and if I could remove that cone without removing the IP? When I crank it over there isn't hardly any fuel coming out the top of the IP housing. Should the lift pump push fuel past the transfer pump? Thanks for reading and would really appreciate any help/tips. Ken
Yes there is a screen in there and no I do not recommend removing the cone because the transfer pump is in there as well and will likely fall down into your belly pan if not super careful. Even though you said you have fuel fuel to the injection pump I would still check fuel pressure to the pump just to be sure. Also try cracking open your injection lines before you crank and let them bleed the air out while cranking until you get consistent spurts out of the lines. Then tighten them and try starting.
Thank you for the reply. I will go out there and check pressure from the lift pump. I do believe there is an air lock in there because it was running really well. My friend that was running it cracked 3 or 4 lines at the IP as he was cranking it while trying to bleed and I read that can cause an air lock. Should the lift pump push fuel past the transfer pump and come out the top of the IP when the return fitting is removed? On my 350c the lift pump will flood the IP rather quickly. Ken
Yes the lp should push fuel thru the pump & out the top w the return connector removed.. Loosening the lines AT THE INJECTORS IS the proper way to bleed the air out of the pump..
Thank you for the reply. I will get out and bleed the lines and see if I can get it to prime. Ken
Went out to the dozer today and put a gauge on the fuel supply line just before the IP and the lift pump would only pump about 1 psi. Time to change the lift pump.
Changed out lift pump and now have good pressure to the IP but still can't get it to pump fuel to injectors. Also the top of the IP cover gets really hot while trying to bleed it, is that normal? I wouldn't think the solenoid would get that hot with fuel going through it. Thanks, Ken
Yes the cover gets pretty hot.. Can u remove the top cover or does it have tamper screws.. The metering valve might be stuck..
Thank you for the reply. I have had the top cover off when I put the shut off solenoid in and the metering valve does move freely. Is there a specific way of checking it?
Just as long as I moves back under its own power it’s loose enough.. U could loosen ALL THE INJECTORS & with the top cover off crank the engine & see if u get fuel there.. U DONT WANT IT TO START.. Just see if u installed the sol. correctly.. & if it starts u have no way to shut it down w the top cover off.!! You’d have to reach in n move the mv to the s/o position.. not fun.!!
Thanks. I'll go out and try it. When I say go out, the machine is about a half mile back in the woods a few miles away.
Went out and removed the top from the IP and cracked the injectors and still can't get fuel to the injectors. Sounds like the IP needs to be rebuilt?
Was wondering if the pump guy rebuilds these pumps? Ken
.. but of course.. I don’t keep the parts in stock tho.. .. they rarely go bad.. & when they do.. it’s catastrophic.. Contact me directly & we’ll chat about it.
How do I contact you directly. I sent an email to your aol address. Was also wondering if the pressure regulating spring in the cone could be stuck. I have pressure from the lift pump going into IP but it doesn't seem like the transfer pump is doing anything. With the top off the IP it doesn't push a whole lot of fuel out. Thanks, Ken
H Ken, I tried responding to your email but it kept coming back.?? If u have a helper.. put your finger over the fuel inlet connector n have someone crank the engine.. u SHOULD feel it sucking it.. IDK how to contact you w/o a good address.. it’s possible the regulating spring has broken, but unlikely..& it’s nothing u should mess with.. Take off the return connector on top n see if your finger gets sucked on at the pump inlet, if not, your gonna hafta pull the pump..
Thank you for the reply. I don't know why the emails aren't coming through. I will send my email address to your aol address and see if that works, I will go out and try the test you recommended and if it isn't working I will pull the pump. Again thank you for the help. Ken
I tried what was suggested and there is no noticeable suction on the inlet with either the return hole plugged or not. Time to pull pump. Thank you, Ken
Let us know how your making out.. If u need help, just yell..
Thanks, I'll keep you posted.
Want to take a minute and give an update. The IP turned out to be seized up. Had the injectors tested and 4 of them were plugged. I don't know how it even ran. It ran great until the pump seized. I want to thank Mike the pump guy for all his help. He is a great resource and I really appreciated his advice. [
Thanks for the update!