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Possible injector pump issues.

1K views 1 reply 2 participants last post by  Freddyack 
#1 ·
Hi, I have a 1999 Chev 3500HD with a 6.5. In the last 4 months, I've done a rebuilt injector pump with a brand new optical sensor, new turbo, new injectors, new fuel lines, clear return lines, new sending unit, new lift pumps, new fuel filters, and a few other random parts.

I changed out the old injector pump, put in a the rebuilt, had it timed and the truck ran great. No codes, no stumbles, it ran smooth and quiet. Fast forward to a few weeks ago and the truck begins starting hard, and dies while out working. We left the truck for the night, I picked up a brand new D-Tech PMD and changed it, figuring it was the usual PMD issues. Truck ran ok that day and the same problem started. I swapped the old PMD with the new PMD and same issues, so I ruled out the PMD. While this was happening, the check engine light came on. I read the codes and it was a PO251, PO335, PO370, PO660. I called the dealer I bought the pump from and he recommended changing the crank sensor. I changed that and no change. Fast forward to today, I start messing around with it and find a bunch of crap in the filter, such as water and sediment. I cleaned the filter housing out, changed the filter, and started the truck again. Checked the fuel through the and the fuel coming out was clean. The truck comes back with a PO251, PO370 code while running. It runs ok once its started, idles fine and revs fine but once you put it into gear it dies.

I've done my research and I don't know whether to condemn my new injector pump (Maybe 2,000 miles on it). Or whether i should look somewhere else. The truck is well maintained, so I'm lost as to where to start looking. BTW, the PMD is remote mounted behind the grill by the horn.

Thank you everyone!
 
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#2 ·
Checked the fuel through the and the fuel coming out was clean. The truck comes back with a PO251, PO370 code while running. It runs ok once its started, idles fine and revs fine but once you put it into gear it dies.
P0251 and P0370 usually point to the Optical Sensor. The OS does not like dirty fuel. Try running a heavy dose of Diesel Kleen in the fuel. Some have had success running Sea Foam in the FFM bowl. You will want to unplug the lift pump to try Sea Foam in the FFM bowl.

Here is a link to the 1999 DTC Diagnostic section of the 1999 C/K Truck Manual: Click Here. This is a .pdf file that will download to your PC. This will give you the step by step for diagnosing the DTC Codes.
 
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