12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

cummins 12v died while driving

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Old 05-15-2014, 05:13 AM
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Default cummins 12v died while driving

ruck starts runs and idles fine until I was going to work this morning it was driving and doing about 30 and it shut off. Got it started again would barely make it to pull over. Dumping white smoke Waited a few mins started back up and went to take off and same thing wouldn't go over 2 grand and die. In park it is perfectly fine. Any ideas?
 
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Old 05-15-2014, 06:58 AM
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Disconnect your fuel shut off solenoid and wire it up. See if it will run properly.
 
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Old 05-15-2014, 11:12 AM
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Agreed with lostsoul, seems like the solenoid is shorting out


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Old 05-15-2014, 11:59 AM
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assuming that the fuel filter's not clogged all to crap, it might also be that the lift pump is gone, and that the injection pump is having to provide its own suction. it's pretty dismal when that happens.
 
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Old 05-15-2014, 12:07 PM
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I have a smaller electric lift pump behind the mechanical one, which isn't making noise anymore. Im wondering if that plugged it up. Or would it just pull through that one?
 
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Old 05-15-2014, 12:13 PM
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a p7100 wont pull fuel it will stick plungers.
 
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Old 05-15-2014, 12:16 PM
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Originally Posted by ebarresi5894
I have a smaller electric lift pump behind the mechanical one, which isn't making noise anymore. Im wondering if that plugged it up. Or would it just pull through that one?


A pump that's no longer pumping is now a source of flow restriction. Do you have enough fuel line to play with to bypass the electric and plumb the mechanical directly to the fuel tank?

Another potential source of restriction is the bowl screen underneath the mechanical lift pump. There's a settling bowl, situated below the pump, and above the starter, that catches and pre-screens tank debris and dirt particles before they have a chance to damage the pump's diaphragm. If you've never had it off, the first time will be kind of a hard twist, and might need 2-3 extensions on your ratchet (not cheater-bars.... extensions. It's a long reach upward if you're lying on the ground). You're unlikely to be able to reach up and just finger-twist it off. When you get it off, the screen is made of white nylon. It'll probably be black and opaque. No fancy procedure or special solvent needed. Just Dawn, a paper towel, and back-flush with warm water. Pat dry with a paper towel, re-install, and then use the pump's thumb-button for re-priming.
 
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Old 05-15-2014, 12:26 PM
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Deleted pre heater a while ago
 
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Old 05-16-2014, 10:58 AM
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Originally Posted by turbo2332
a p7100 wont pull fuel it will stick plungers.


Correction: it will pull fuel, but, not very well and not very long. I made it across Corpus Christi at 20mph or less, mostly just above idle, with a bad lift pump.

It wasn't enjoyable.
 
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Old 05-16-2014, 11:00 AM
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Originally Posted by ebarresi5894
Deleted pre heater a while ago

In that case, if the electric pump has crapped out, it's going to act as a restriction-point, keeping your lift pump from moving fuel very well. Might as well have a pair of vise-grips on your fuel line.
 


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