94 Dodge, hard starting?

[Chace TX]

A friend of mine has 94 Cummins, he is not much of a mechanic, so I usually help him out when he has a problem. His pickup was starting on the first rotation, but now it has to be cranked before it will start. More cranking is required when it has been sitting for a while. I know the fuel lines are usually the culprit, and they may be in this case. But, the last time I was helping him I took the starter off and replaced a contact, I checked the fuel lines and they were braided stainless from the pump down to the frame. Since that was not a problem, I did not trace the lines back to see if they were leaking. I also noticed the that the overflow valve will make a hissing sound after you pump the thumb pump for a while (after a filter change). How do you check the overflow valve to see if its good? What else can I check?

 

[Strick-9]

Follow the braided stainless lines (two of them) from the frame upwards towards the fuel filter. They eventually turn into rubber for a short piece. That is where they usually break down and start sucking air. I replaced mine less than a year ago and last week they were already cracked again. No starting troubles yet, but that would have been next. It was sure easier changing them with the engine out.



Good luck finding them and getting a wrench on the hose clamps. Some trucks are harder than others.



-Chris

 

[Joe G.]

Chris has probably got it right. There are a couple of other things that could be wrong, but the hoses are the prime suspect.



On the '94 you can get a little more room to work by removing the nuts that fasten the master cylinder to the vacuum booster and leaning the master cylinder toward the fender. It also helps to remove the starter. Long skinny arms with an extra joint in your fore arms helps too.



If the idle is low it can start kind of slow. Check this by putting a little pressure on the pedal and see if that helps.



There is a spring in the overflow valve that should be . 550" long. It sometimes gets shorter so the valve won't hold the pressure. Some guys stretch it, but that doesn't last. I shimmed mine up a little to get it back to the right length. That was many many miles ago and it's still working fine.

 

[Chace TX]

Thanks

I will check the hoses, and then the overflow valve. Thanks for the tips.

Chace

 

[Dieselnerd]

I had the same problem several weeks ago. I replaced the fuel lines, checked the fuel heater for leaks, checked the overflow valve and it still started only after priming with the pushbutton. The problem was the lift pump. They do go bad and if yours is the original there is a newer version available from Cummins. What goes bad in the pump is the check valves. They are not available as a separate item you must get a new pump.



12 Valve Lift Pump, latest style, Cummins P/N 3936316



Cost is around $150