I have finally gotten my truck back together and somewhat running. I bought a 1996 GMC K1500 with a 6.5L "s". It had a blown head gasket as a result of a failed water pump. I never heard it run before and don't know much history.

Now that it kind of runs there are some codes. When I ran the scan, three codes came up: P0251, P0370, and P1214. Does this pretty much sum up that I need to replace the injection pump?

I have installed new injectors and relocated the PMD too.

The truck starts but once it does it smokes real bad and very of evident of unburned fuel. It will not rev above 1500 rpm. When revving that high, the smoke turns black.

Are there any opinions out there about the electronic filter on the injection pump?

Final questions are what happens when the lift pump needs replacing and the OPS?

Thanks!

Frank

Raleigh, NC

i was getting a P0251 and P0370 when i had a bad lift pump. At Wide open throttle the truck would jerk violently after about 10-15 seconds, thorw those codes and it had no power until i cleared the codes.

I'd check to see if your truck has the optic sensor filter harness. 96 and up didn't need it, but some had it. my 96 had the filter harness and it was causing my P0251 code. After i removed it, the code never came back.

Ok. Mine does have the filter and I have been told by a local source to remove that thing too. I will do that. I was told that the P1214 code was a definite indicator that my pump is bad. How does the lift pump work with the injection pump? Thanks for the help.

The lift pump is on the inside of the driver's side frame rail. it's a solenoid style pump that provides fuel to the Injection pump. Without it the IP has to suck the fuel from the fuel tank, which means the IP has to work harder and thus shortening it's life.

As far as P1214, i'm unsure. I don't have my 6.5 book or my code reader at my access right now. That reminds me i have to find that darn book.

I just found the lift pump diagnostic instructions in the FAQs. I have done all that in the process of bleeding the fuel system and know my lift pump is working properly.

did you check the pressure at the T-valve under WOT while driving(long length of hose on a pressure gauge works). that's what matter's more so than the pressure at idle.

I haven't been able to drive it much. Just from my barn down to the road and back (about 200 total yards). Only WOT is while in Park and it only revs to around 1500 rpm. I have been reading in the reference section and it seems difficult to determine if the PMD is bad or the injection pump. But the codes seem to be clearly saying the IP has issues.

Is it possible that somehow I have the fuel lines crossed? Where is the diagram for lines routing?