4d55t starts and idles, then dies, no accelleration.. any clues?

[Dieseldude]

I purchased this truck 1983 dodge d50, knowing it was a pig in a poke. Old owner is diseased and I have no prior info. Wife said it broke down, then he was working on it and never got it running then it sat for 10 years. Today with fresh diesel, it cranks fires and idles for about a minute then craps out. I have bled the injectors, seems lift pump is supplying adaquate fuel to the injection pump. Removed timing cover verified timing is correct on the belt, have not checked lift timing on the injection pump. I need the manual to follow procedure. I have a feely something is gooed up in the injection pump. Any good service manuals online that show the disassembly of the injection pump, are rebuild kits available.. any help or suggestions about be appreciated, as well as links to technical data. Thanks 😊

[camoit]

Sounds like it's sucking air. I would drop in new fuel lines with the proper clamps to make sure that is good.
I would also make sure the filters are new.
From that it might be the lift pump not giving enough pressure. It is 30 years old and rubber gets hard.

[dancinggecko]

Sucking air definitely sounds like it could be a culprit. What does it do when it dies? Does is just stop all at once like you shut the key off, or does it get weaker and weaker until it dies?

[Uncle Spence]

I would start at the fuel filters as well. Will it run if you just have the fuel supply line stuck in a bottle of fuel? Bypass everything from the tank to the pump that way.
If that doesn't work, then keep troubleshooting your way towards the injectors.

[Dieseldude]

It gets weaker and weaker till it stalls, then it will start back up and do the same thing. Runs for about 30 sec then quits or does if I crack throttle valve. It has an in line pump between tank and fuel filter housing. I assume original pump was in file filter housing since it has alot of wires to it.

[Dieseldude]

I removed the return line while it was runing it's returning fuel to the tank, did not show signs of being airated from a bad supply line. Flowed clear no bubbles. Can someone verify the original lift pump location, in the filter housing or other location under the vehicle or in tank?

[Dieseldude]

Some more diagnosis, I eliminated the fuel system completely, ran a new pump and new hoses to a five gallon jug of new fresh diesel. Same results, starts then runs for one minute.. or less then dies. I advanced injection pump and now it will accelerate but then acts like a gas motor starved for fuel and dies.. will do this over and over again without having to bleed injectors.. Wich makes me think internal injection pump issue, blockage or failure.. any feedback?

[Bjamin]

Have you pulled the injectors to look at the nozzle end? When I did my head and had everything apart I looked at mine. One of them looked like the end was starting to get pitted and I questioned whether they'd continue to flow for any length of time. I do not daily the truck but 2k later and everything is okay.
Others with more experience can verify if a bad spray can cause the issues you are having

[skullzaflare]

its possible the cut off solenoid on the side of the injection pump (powered to allow fuel into pump) is failing and slowly closes as the solenoid gets warm

[Dieseldude]

Good thought! I'll try it outside the pump and see if that's happening. Thx

[Uncle Spence]

Can someone verify the original lift pump location, in the filter housing or other location under the vehicle or in tank?

These trucks do not have a lift pump from the tank. The injection pump is the only thing bringing fuel from the tank to the injector.

its possible the cut off solenoid on the side of the injection pump (powered to allow fuel into pump) is failing and slowly closes as the solenoid gets warm

Never would have thought as this as an issue. It's definitely plausible. I guess I just assume it would fail all at once and either let fuel past or not. I would be more suspicious of a wire or ground if you narrowed it down to the cut off solenoid. Good broad thinking though.

[dancinggecko]

That's actually a pretty good place to start. On a lot of the Stanadyne pumps used on the old Ford and GM diesels that's a fairly common problem that can often be mistaken for a dead injection pump. Maybe that's all that's wrong with yours

[Dieseldude]

I will update, have not had any time to tinker with it yet. Thanks all for the feedback and suggestions!

[camoit]

One thing to test is take your fuel bucket and place it above the pump. Then start it. If it runs good because of siphon pressure to the pump then you can assume it's probably the pump bypassing internally and unable to actually draw the fuel from the tank.

[Dieseldude]

I added a marine electric fuel pump with water separator and filter in place of the factory fuel filter and it starts and runs for a longer period but still eventually cuts out. Either the injection pump is bad or there is a pin hole in the hard line from the tank airating the fuel

[camoit]

Either the injection pump is bad or there is a pin hole in the hard line from the tank airating the fuel

You can plug the end of the line and pressurize the line and let it sit over clean concrete and just leave it under pressure. If it has a hole it will show up. It might take a couple of hours but it should show up. But it's sounding like it's a bad pump.
If there is air in the system it should show up in the return fuel. Just put a hose in a bucket and run it. Keep the line at the bottom so you can look for air bubbles.

[Dieseldude]

Yup injection pump it is.. it's definitely shot. Any sources for a rebuild kit? I'm going to try it myself before sending it out. I have done a few rotary pumps on Perkins diesels with good success. Thans for all the solid advise.

[camoit]

Diamond Diesel in California might be able to help. Or just send them the pump is the best way. Then they can run it on the test bench.

[Dieseldude]

Ok I have the injection pump disassembled in a hundred pieces, I am trying to get parts for it. I have the numbers stamped on the housing yet the little silver sticker is illegeble that one has the info I need to get it calibrated correctly. The rollers and roller plate are worn and blued from heat. Obviously the scavenger side of pump failed and it ran low on fuel and got hot. If anyone has a d-50 with a 4d-55t and can still read that sticker that is what my parts guy needs to order the correct internal parts. Or if anyone knows an available bolt on replacement pump, aftermarket or otherwise that would be calibrated close to original that would be great. Thanks

[85Ram50]

Try using a black light and other kinds/colors of light to read the sticker. You never know that ink they used might have left a residue that will reflect.

[dancinggecko]

I finally remembered to go take a picture of the numbers on the side of my pump. I hope these are the ones you need, because I don't think I can get a good picture of the other side. My pump is off of an 83 model truck.