GMC 99 will not start
 

I need some help. We have a 99, 3500, 5.7 with duel tanks.
It will not start. We have tried a new computer,Installed a new fuel pump,filter, wires,and plugs. The parts replaced needed it. But now the pump will not pump. we have lots of spark.When a shot of gas ispoured in the engin starts and runs till the gas is used. What now?

RE: GMC 99 will not start
 

Is the pump running?..whats the fuel pressure/

RE: GMC 99 will not start
 

The pump runs when power hooked direct with 45psi.
The pump will not run when hooked in the wire harness as factory set.

RE: GMC 99 will not start
 

Do chevys have a fuel relay like dodges do. I know on my dads 1993 dodge the fuel pump had no power and the it turned out to be a $7 fuel relay. But im not sure if chevys have them.

RE: GMC 99 will not start
 

it ain't about to run with 45 psi....it takes nearer 53 for it to pop

RE: GMC 99 will not start
 

We will try again, Fuel pressure on rechecking the test is at the required level and the relay replaced, still no start. The factory ground's have been verifyed.

RE: GMC 99 will not start
 

let's back up here...it ran fine until it was worked on?..or did it die on the road?

you say you replaced the pcm,was it programmed and theft learned correctly?

RE: GMC 99 will not start
 

The truck died on the road. The PCM was from another truck that was running fine at the time of removal. Thanks for you interest, hopefully a answer can be found.

RE: GMC 99 will not start
 

Here is my thinking...it died on the road...fuel pump was bad...

however,you put a pcm in,and did not program it....so even though you put the pump in later,the pcm has it down.

do you have the original pcm to try?

RE: GMC 99 will not start
 

Yes I have the origional. The parst replaced in order were the fuel pump first(no start) the fuel filter(no start)the PCM )no Start. After each piece replaced the engine would run if gas put in by hand. The engine still will not run without gas put in by hand. The test light indicates power at the pump.