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Discussion Starter #1
Working on a 91 w350 non inter cooled 5.9 cummins. I’m having trouble with bleed down. I had to crack injectors to get pickup to start and use a shot of ether to get it going. Once going it will run like a top until you turn it off. After sitting for a few minutes it will not restart without cracking injectors and some starting fluid again. I took off the lift pump and the diaphragm seemed to be screwed up so I installed a new one. Now that I have it on the pickup can sit for 20-30 minutes and then restart but still has some bleed down. If left overnight it will not restart without “normal starting procedure”. Any help would be greatly appreciated.
 

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You have a air leak on the inlet side of the lift pump. Use a air hose and pressure the fuel tank. It doesn't take much pressure a few pounds is all. Then watch for leaking fuel.

The snap fittings on the fuel inlet to the pump and out of the tank has O-rings on it. One or both are most likely bad.
 

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Your truck should have a short piece of rubber fuel line on top of the fuel tank.... those like to rot away.
 

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Your sucking air into the fuel system like said above, old fuel lines will crack and let air into the fuel system.

Over night the next morning before you start it open the bleeder for the filter and manually pump the LP and watch for air bubbles to come out. If there is air bubb;les keep pumping until all the bubbles are out and just fuel coming out and it will fire right up.
 

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Your sucking air into the fuel system like said above, old fuel lines will crack and let air into the fuel system.

Over night the next morning before you start it open the bleeder for the filter and manually pump the LP and watch for air bubbles to come out. If there is air bubbles keep pumping until all the bubbles are out and just fuel coming out and it will fire right up.
 

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Discussion Starter #6
Hey, sorry it has been so long since I have been on. I followed the above advice and replaced the worn and cracked fuel lines into the sending unit. In the process I broke the sending unit. I replaced it with one out of a 96. I don’t know if I screwed up doing so. I am now having trouble of course because the electrical connector is different. The one on the pump is a 6 pin and the old one on my pickup seems to be a 5? pin. Any suggestions on how to fix this issue?
 

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So is it running and starting like it's supposed to? From what i've read on the 2nd Gen section the 96's fuel modules have issues with the fuel level sensors going bad. Also they no longer make them for it also for some reason.
 

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Discussion Starter #8
Well, now it starts. But I wasn’t sure if my pig tail had to be connected for the pump to work correctly or if that was just for fuel level. It starts about like it did before and sat and idled for a good minute or so and then it started to lose fuel. I pumped the accelerator and it kept running and would run as long as I kept my foot lightly on the pedal. If I let off it would lose fuel and die.
 

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Well, now it starts. But I wasn’t sure if my pig tail had to be connected for the pump to work correctly or if that was just for fuel level. It starts about like it did before and sat and idled for a good minute or so and then it started to lose fuel. I pumped the accelerator and it kept running and would run as long as I kept my foot lightly on the pedal. If I let off it would lose fuel and die.
What pump the 12v's don't use a intank pump. If your module has a intank pump then it's for a gas truck and the pump is causing problems by restricting fuel flowing to the engine mounted LP.
 

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Discussion Starter #11
No there is no pump. Just a mistake on my part. I meant the sending unit. Do the pigtails have to be connected or is that just for fuel level?
 

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So your using the sending unit for a 96 Dodge diesel truck on your 1st gen fuel tank module? And the wiring from your truck has to be connected in order for the sender to read, but not sure if the 96's is the same ohms as the 1st Gens.
 

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I got the whole drop in module for the 96. And yes the connector is different.
You'll have to get a connector from a 96 and then cut the connector off the 1st Gens wires and then wire the 96's connector to the 1st Gens wiring.
 

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Discussion Starter #15
Ok. Thank you. Is there an easier way? I couldn’t find the sending unit for the First Gen that wasn’t $700. Is going with like an air dog or something like that simpler?
 

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Ok. Thank you. Is there an easier way? I couldn’t find the sending unit for the First Gen that wasn’t $700. Is going with like an air dog or something like that simpler?
A electronic LP isn't simpler it's only making a simple engine not as dependable. A sending unit for the module shouldn't be $700.
 
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