I just bought a 1975 JD450B Dozer. I have changed All the Fluids and Filters (Air, Oil, Fuel, Hydraulics) New Fuel Pump. It starts fine, but after 5 minutes it stalls and won't restart for hours. (Almost acts like it is overheating, but it is not.) Batteries charged, etc. No Air leaks in the fuel system that I know of.
Mark, look for a fuel return line that might be closed off. Or a fuel tank vent that might be closed(try running in clean area with cap off tank). Later Bob
Mark, also check the fuel supply line all the way from the tank to the pump, and all fittings in between. You could have some trash in a line or fitting (don't forget the fitting coming out of the tank) and you could have a supply line collapsing and shutting off the fuel.
mark had same type of issue a while back and turned out to be electric fuel pickup pump was full of trash, there is a screen in there mine was almost solid with junk but would still run abit. best bet would be to replace line from tank to pump and verify you have solid fuel from pump outlet.
Took an air hose and blew back from injector pump to tank. Seems OK. (Really bubbled fuel in tank). Blew fuel feed line from fuel pump back to tank. Same thing, seems clear. I do notice that if I keep the RPMs low (1000-1200) it runs for much longer, (but dies under any load). If I bump up the RPM, it dies soon after. Also, it acts like it is overheating but the radiator fluid is cool. Is there a way to check if coolant is actually pumping through the engine? (No water in oil so that seems good)
Sounds like it won't run long enough to overheat? with engine running you should be able to remove rad cap and look for fluid movement in rad, I'm not sure if there is a thermostat so that may play a role. Any smoke at all white or black. Also on the rearward end of injection pump there is a plug top and bottom with a spring and a check at bottom I've seen the rubber check in bottom squished funny and not seating properly, check here if you have solid fuel (no air) at injection pump from electric pump. I had no leaks at all when my pump was clogged but it still cavitated and created lots of air spraying out with the fuel, should be solid stream of fuel but pull the low pressure fuel line at injection pump I beleive it tees into high pressure return on injection pump. Oh and when you do get it running good don't let it sit too long outside or will have trouble with steering clutches. How long long has this machine been sitting because they pull fuel from bottom of tank and if your cap is bad or anything all the garbage or water will be getting pulled first so if your not sure about fuel quality drain it and start fresh with a clear filter under seat or side of engine somewhere you can see it.
Did you run it with the fuel cap off??? Later Bob
Ran with cap loose. No change
Machine sat for years. Drained tank, new Fuel and filters, etc. No visable flow through the radiator. (New fluid and filled to the top) But may not run long enough for thermostat to open. Machine won't steer to the left. I removed the pin at the end of the control valve so I could get more throw to see if I could unstick things before thr brake engages. haven't been able to run the machine long enough to see if that helps. I will mess with the injector more this weekend, but I don't want to make any adjustments that might hurt the engine, blow a piston, etc.
Okay Mark, you have ruled out a vacume building in the fuel tank. It is definatly a fuel quantity related problem. You leave machine for a time enough fuel gets through something so you can start and run to burn that quantity of fuel. Re faster speed shorter running time. I have a feeling that there is something like an old sock floating around in your tank and getting sucked into the fuel line. OR as I have recently seen a pickup line that was loose and sometimes worked it's way around untill it blocked it's self against a tank wall. To rule this out take fuel lines off and run them into another fuel container. On the brighter side if this machine didn't have this problem it wouldn't have been for sale, you would have had to buy someone else's machine with a different problem. Later Bob
I think your lift pump is fried. Trash will knock them out in a hurry. There's some reason for somebody to replace it. Water in the fuel is another real possibility, add some fuel conditioner that gets rid of it like FPPF. Take it off and see if you can push on the rod that runs on the cam to see if it's working right. You need to have a pencil sized stream of fuel coming out of your supply line at your lift pump when the tank is full.
Governor flexring is failing plugging return check valve, a very common problem with those injection pumps. Good luck.
Sorry I haven't gotten back to you or anyone reguarding my dozer, but I was waiting on a mechanic to take a look at it. What has noticed so far is that the level in the oil dip stick has risen considerably. Fuel getting into Oil system through Fuel injector maybe? This would explain the the motor acting like it seizes after running for a few minutes. (Oil viscosity thinning out when engine runs?)
There are some seals on the injection pump that keep the diesel out of the oil. I've had the same thing happen on 3 or 4 JD tractors, from the governor flex ring clogging up the return line like Tom V said. You'll find little pieces of rubber in the return line elbow at the pump as it has a little bitty glass ball in it to keep dirt from entering pump. Pull it off and have it rebuilt. Make sure you keep the governor wired open when you reinstall so it doesn't tear those seals.