Slow/None Responsive RPM

[George McGuire]

I just purchased a 94 GMC K2500 4X4 with 210,000 miles on it. It has some blow by, oil pressure is a little low but runs nicely(sounds good). The engine is slow to rev up and when hot, in gear, sometimes will not rev up enough to move the truck. It has a fast idle switch on it though and if I turn it on the engine will rev up and the truck will move. Very strange!!! I have changed the pump, no difference, new wastegate solenoid, replaced the fuel pedal, replaced the fuel filter, andverified the lift pump to be fine. Seems like it may have a wiring problem, or an ECM problem. Any and all thoughts would be appreciated. The transmission has a gauge on it and I have seen it as high as 180 degrees, but normally about 140. Need help!!!

[Kennedy]

Being a 1994, I'd be curious as to what the pump model number is AND was, along with the 4 letter code on the eprom.

I am very insistant about getting these details when a guy orders a pump or a chip for a 1994, and 1995 F engine. There are a LOT more trucks than one would think running around mis-matched Pump/proms as parts swappers seldom know the "rules".

[George McGuire]

John,
What is the EPROM you are talking about? I will get the info for the pumps once I know exactly what I am looking for and forward it to you. I was under the impression that you can only buy a 5521 pump now, even though some used 5067, 5288 and so on.I appreciate any info you can offer.
Thanks

George

[ttpost]

have you pulled the codes??

[George McGuire]

I have pulled the codes, I had a waste gate code, I replaced the solenoid. Also got code 36 or 78, I forget now, I think, something about injection pulse too long. I was wondering if it could be a badly worn timing chain????