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

Do P-Pumps Knock When Going Out

Old Jan 19, 2009 | 09:33 PM
  #1  
haulitrite's Avatar
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Default Do P-Pumps Knock When Going Out

I have been having problems with fuel delivery on my truck. I haven't been able to figure out what it is, but tonight when I was in the driveway it died. When I started it it started to knock on the pump side. I couldn't tell if it was the p-pump or the lift pump.

After it was knocking it died after about 15 seconds of running. I primed the lift pump and it stoped knocking but it was still very hard to start.

1994 12 valve

any help before I take it in would be great
 
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Old Jan 19, 2009 | 09:46 PM
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soundls like your getting air in the lines
 
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Old Jan 20, 2009 | 12:55 PM
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I had the same problem just a few days ago.. Iagree sounds like air.. You can get a piece of clear hose and splice into the fuel line and start it up and see if there are any air bubbles in it to make sure..
 
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Old Jan 21, 2009 | 12:45 AM
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just replace all the rubber fuel lines i know there are 4 for sure to on the pump and two by the tank
 
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Old Jan 25, 2009 | 06:05 PM
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I did splice a clear fuel line in and it didn't have any air. I also checked the pressure and it was fine
 
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Old Jan 25, 2009 | 09:01 PM
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They go out?
 
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Old May 17, 2012 | 06:47 AM
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This is bs mine started knockn for a short second yesterdat it was breif couldnt tell if it was valves or pump im adjustin lash regardless did ur pump go out yet?
 
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Old Jun 11, 2012 | 04:08 PM
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I have a 12 valve also and mine you will be on interstate and interstate only and it will loose power start with a peck on the injection pump and will try to die out having seem like air is in the line. It only does on interstate but idk if its supply or plunger sticking also throttle seems to lock while it is pecking
 
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Old Jul 15, 2012 | 08:10 AM
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Originally Posted by haulitrite
I have been having problems with fuel delivery on my truck. I haven't been able to figure out what it is, but tonight when I was in the driveway it died. When I started it it started to knock on the pump side. I couldn't tell if it was the p-pump or the lift pump.

After it was knocking it died after about 15 seconds of running. I primed the lift pump and it stoped knocking but it was still very hard to start.

1994 12 valve

any help before I take it in would be great
Deff. Air in lines
 
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Old Jul 15, 2012 | 04:09 PM
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Thread is 2 years old
 
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