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

94 cummins only starts when fuel filters full

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Old Dec 9, 2012 | 08:48 PM
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Default 94 cummins only starts when fuel filters full

the only time i can get my truck started is when i put diesel in the fuel filter then it runs for about 30 seconds and dies anyone know what the problem is?
 
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Old Dec 9, 2012 | 11:03 PM
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Bad fuel line filter needs to be full all he time
 
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Old Dec 9, 2012 | 11:16 PM
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Originally Posted by tiremann9669
Bad fuel line filter needs to be full all he time
So you dont think thered a leak in the line and not the lift pump?
 
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Old Dec 9, 2012 | 11:59 PM
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the feed line coming from the tank unit is notorious for rotting out and leaking air. look at the lines coming from the tank and ill guarantee its rotted out. save yourself the future headache and put in a sump. i did a sump and all new 3/8'' lines to the lp and havent had a single problem since.
 
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Old Dec 10, 2012 | 09:13 PM
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can someone tell me how much fuel line i need to replace from the tank to the lift pump and what size

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got the truck running but if i press on the pedal and let off real fast it dies is it something to do with the injection pump being turned up?
 

Last edited by jonesy9310; Dec 10, 2012 at 09:13 PM. Reason: Automerged Doublepost
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Old Dec 10, 2012 | 09:23 PM
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The fact that you're getting air in the system points to a line and they're 3/8, could possibly be the sending unit also so like said above might need a sump or a draw straw.
 
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Old Dec 10, 2012 | 09:50 PM
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Originally Posted by tiremann9669
The fact that you're getting air in the system points to a line and they're 3/8, could possibly be the sending unit also so like said above might need a sump or a draw straw.
Thanks got it runnning i guess my fuel gauge is off i haf air in the lines from running out of fuel. But now when i hit the gas real fast and let off it dies idk if its from the injection pump being turned up or what
 
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Old Dec 13, 2012 | 06:39 PM
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Originally Posted by jonesy9310
Thanks got it runnning i guess my fuel gauge is off i haf air in the lines from running out of fuel. But now when i hit the gas real fast and let off it dies idk if its from the injection pump being turned up or what
Just need to bring your idle up by a couple hundred rpm. Got nothing to do with turn-upped-ness. Just needs to be sped up a little. Mine did that 2-3 times over the course of the last 15 years.
 
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Old Dec 19, 2012 | 02:05 PM
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Not sure about a 94, but on my 97 there is a prefilter before the heater that gets overlooked. Mine was so gummed up that fuel was forcing itself around the screen... Probably never cleaned in the 330,000 miles before I discovered it...
 
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