95 GMC Jimmy won't crank!

:banghead: I have a 95 GMC Jimmy 4.3 Vortec and having a serious cranking problem that i cannot seem to figure it out. After testing several things, I have replaced injectors,fuel filter, fuel pump, coil, distributer cap, rotor button, spark plugs, wires, ignition module, iac valve, tps. This problem started out of the blue and i was stuck at work and it would not crank and i shot some starting fluid and it started but the rpm's were surging and when i put into gear it jerked and would not go below 1200 rpm, Made it home and done some test and went to crank it up to do some more pondering and still wouldn't crank not even with starting fluid, Thats when i started to replace the parts listed above and after all those parts still no hope, I am getting fuel, blue spark on all wires. If anybody could help me out it would be greatly appreciative. :confused:

:banghead: I have a 95 GMC Jimmy 4.3 Vortec and having a serious cranking problem that i cannot seem to figure it out. After testing several things, I have replaced injectors,fuel filter, fuel pump, coil, distributer cap, rotor button, spark plugs, wires, ignition module, iac valve, tps. This problem started out of the blue and i was stuck at work and it would not crank and i shot some starting fluid and it started but the rpm's were surging and when i put into gear it jerked and would not go below 1200 rpm, Made it home and done some test and went to crank it up to do some more pondering and still wouldn't crank not even with starting fluid, Thats when i started to replace the parts listed above and after all those parts still no hope, I am getting fuel, blue spark on all wires. If anybody could help me out it would be greatly appreciative. :confused:

How much fuel pressure?
Is this a W Code engine?
Flat top or old style dist?
TBI or multi port injection?

fuel test when pump is running is 60 when pump quits it is 55 for about four minutes it is a mpi and has vin w dist is vertical

Fuel pressure isin specs but make sure it has 60 when no start.
Also spark to all plugs and injector pulse when no start.
Also check for codes.
The start after starting fluid sounds like fuel deliver problem.

there are no codes and done fuel pressure test agian it checked out fine now the truck wont crnck with starting fluid check to make sure i ws getin fire i was and it was blue sparks checked the injectors and they are operating normal took the battery cables off before i left for work maybe it wil somehow reset the computer but i am willing to try anything you ask cause i am puzzled

there are no codes and done fuel pressure test agian it checked out fine now the truck wont crnck with starting fluid check to make sure i ws getin fire i was and it was blue sparks checked the injectors and they are operating normal took the battery cables off before i left for work maybe it wil somehow reset the computer but i am willing to try anything you ask cause i am puzzled

If you have spark and fuel and injector pulse it should start.
Go to the basics and check compression.
Post back compression readings.

the compression was about around 135 for all six cylinders

the compression was about around 135 for all six cylinders

It should start and run.
Are plugs wet or dryon end?
Go back over everything and see if it is losing any of them.

i wont have a chance to work on till the weekend but i will post back

the plugs are dry on the end, so i started back on the fuel hook my gauge up turn key in the on position pump comes on about 60 61 psi pump shuts off it remain at 55 56 for well more than four minutes, pulled out injectors replaced and also replaced computer, the truck will only start with starting fluid guage reads 52 while running shut truck off and try to restart will not run unless spray starting fluid, when truck is running it idles at 1600 1700.:confused::confused::confused:

the plugs are dry on the end, so i started back on the fuel hook my gauge up turn key in the on position pump comes on about 60 61 psi pump shuts off it remain at 55 56 for well more than four minutes, pulled out injectors replaced and also replaced computer, the truck will only start with starting fluid guage reads 52 while running shut truck off and try to restart will not run unless spray starting fluid, when truck is running it idles at 1600 1700.:confused::confused::confused:

What is engine cranking fuel pressure?
You need around 60 engine cranking pressure to squirt inhjectors.
52 engine runing is also low pressure.

If you have to spary stat stuff in it to start you have a fuel delivery problem.
Kinda. looks like low pressure some place.

You fuel pressure is to low.
Specs on it is 55/61 lbs of pressure
Here is some guide lines of fuel pressure checking.

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.

Cold start on yours should be 60 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 55/61 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
If pressure does not come up with return line pinched or blocked off.
Go to fuel filter and hook a gauge direct to a line at fuel filter.
Pressure should come up to 75 or more and will hold after fuel pump is turned off.
If it leaks down there after fuel pump is turned off it is LEAKING BACK THREW PUMP CHECK VALVE OR PUMP MODULE LINES.
Post back all your fuel pressure readings.
MT

the plugs are dry on the end, so i started back on the fuel hook my gauge up turn key in the on position pump comes on about 60 61 psi pump shuts off it remain at 55 56 for well more than four minutes, pulled out injectors replaced and also replaced computer, the truck will only start with starting fluid guage reads 52 while running shut truck off and try to restart will not run unless spray starting fluid, when truck is running it idles at 1600 1700.:confused::confused::confused:

What is engine cranking fuel pressure?
You need around 60 engine cranking pressure to squirt inhjectors.
52 engine runing is also low pressure.

If you have to spary start stuff in it to start you have a fuel delivery problem.
Kinda. looks like low pressure some place.

You fuel pressure is to low.
Specs on it is 55/61 lbs of pressure
Here is some guide lines of fuel pressure checking.

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.

Cold start on yours should be 60 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 55/61 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
If pressure does not come up with return line pinched or blocked off.
Go to fuel filter and hook a gauge direct to a line at fuel filter.
Pressure should come up to 75 or more and will hold after fuel pump is turned off.
If it leaks down there after fuel pump is turned off it is LEAKING BACK THREW PUMP CHECK VALVE OR PUMP MODULE LINES.
Post back all your fuel pressure readings.
MT

cranking pressure is around 61, while engine is running pressure would be around 52 when you hit the throttle it jumps up to 60 61, shut the truck off it will remain around 56 for four five minutes, full pressure is about 84.

cranking pressure is around 61, while engine is running pressure would be around 52 when you hit the throttle it jumps up to 60 61, shut the truck off it will remain around 56 for four five minutes, full pressure is about 84.

Pressure should start and run it.
Check for good injector pulse when crnking engine.
And confirm good spark cranking.

Does engine run good after starting
Any check engine lights or codes?

got me a set of noid lights and hooked it up and i was not gettin any pulse so i changed the computer and distributer i left the battery cables off for thirty minutes to ensure there wasnt any voltage hook cables up checked for a pulse and i have one plugged my injectors up and finally didnt have to use starting fuild i still need to put the timing light on it but at least it is runnig THANKS FOR ALL YOUR TIME AND HELP

got me a set of noid lights and hooked it up and i was not gettin any pulse so i changed the computer and distributer i left the battery cables off for thirty minutes to ensure there wasnt any voltage hook cables up checked for a pulse and i have one plugged my injectors up and finally didnt have to use starting fuild i still need to put the timing light on it but at least it is runnig THANKS FOR ALL YOUR TIME AND HELP

You are welcome and thanks for posting back how it went.
Good Luck