'96 w/Pump problem..help please

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Cumminspr513

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I just picked up a '96 Dodge 2500 4x4 5spd the other day for $2200 green backs. The owner said the truck had a fuel problem but he knew nothing about diesels so he just needed it gone. I get the truck home to see whats goin on and find that when i start it i have to give it a little throttle and when it lites the rpms just a bit and almost have to sit and feather the throttle to keep it running. If i let off the petal the truck will slowly drop in rmps and then shut off. IM thinking possible lift pump or overflow valve issues but possibly something else......Please Help
 
sounds like you need to bump the idle a bit. common event with p pumped motors. I'm sure someone will chime in with the diagram that shows the idle adjustment screw. it's at the rear of the pump.
 
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Cumminspr513 said:
I just picked up a '96 Dodge 2500 4x4 5spd the other day for $2200 green backs. The owner said the truck had a fuel problem but he knew nothing about diesels so he just needed it gone. I get the truck home to see whats goin on and find that when i start it i have to give it a little throttle and when it lites the rpms just a bit and almost have to sit and feather the throttle to keep it running. If i let off the petal the truck will slowly drop in rmps and then shut off. IM thinking possible lift pump or overflow valve issues but possibly something else......Please Help
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Not unusual at all to have to give them a bit of throttle to lite, especially if they are mostly original, but should keep running.
First thing to do is bump the idle speed up to where it will idle, around 650-700. Then you can start checking fuel pressure, leaks, etc.
The idle speed screw is well hidden on the rear of the injection pump.

My opinion is for that price you made a steal unless it is a real rust bucket, smoking, etc. Good luck.
 
Well i went ahead and took alook at the idle screw/bolt and it seem that it has already been picked up a few turns. I started the truck and it runs fine around 850 or so rpms for about 45 seconds when it drops off even when my foot is on the throttle. At the same time i get a ticking sound from the injection pump almost like it has run dry and this happens as the truck is stalling. If i try to restart after this happens the truck will crank alot like there is no feul there...... im not sure at this point.
 
Sounds like the lift pump isn't working very good. The overflow valve may be worn out also. I would check fuel pressure or replace both of them and see what happens.
 
im just goin to replace the overflow and run an aftermarket fuel system to eliminate all the issues, i have big plans for the pump anyway.
 
Now im really not sure whats goin on with this pump. I went and started the truck today just cause and it started and ran at idle like there was nothing wrong. Took off around the block to check things out and made it about .5 mile from the driveway and it just cut out like its just shutting off. It only seems to do it as soon as you let off the throttle seems almost your rollin the key back to shut it down.
 
Check the shutoff solenoid to see if it's pulling up all the way. It might be binding up also.
 
Talked to a friend from up this way that seems to know these pumps like the back of his hand. He is saying it sounds like a pin in the pump is broken. Dose anyone know what this pin is that he is talking about or what it dise he didnt really go into it.
 
Replace the fuel filter 1st. check the shut-off soleniod.

If that doesnt solve it might be sucking air into the fuel system, like from the plastic fitting at the gas tank. Try to rig a clear plastic hose where the pressure line meets the pump and see if air bubbles come through. 7 bucks at home depot gets you 10 feet. At the same time, If it were me, Go pick up the cheapest fuel pressure gauge you can find and a check valve to control aggitation of the plungers in the pump. Hardware store carrys them; And dont be worried about if its fuel safe, its going to be very temporary. When a 94-98 12 valve is running you cant read gauge without one. Its to sensative to all 6 plungers in the p pump moving up and down forcing fuel into one fitting....pull push pull push, so the gauge will go from 5-80psi a million miles and hour. With the check valve rigged up before the gauge, just barely crack it open, and i mean just barely. The reason i say get the gauge is so you can tell if your lift pump is bad at the same time. If its not sucking air then fuel pressure would be my next guess. If it is sucking air before the lift pump, like at the tank, it can make your fuel pressure gauge read low to, keep this in mind. So....from the pressure line to the p pump is a section of clear hose, with a "T" in it. at the "T" will be your check valve, then a line to your fuel pressure gauge. this is all typically 1/8th inch plastic line. its really not that complicated, sounds like i but its not. I can help you if you need, PM me and if needed ill give you my cell number
 
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