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Daves71, ASE Certified Technician
Category: Chevy
Satisfied Customers: 719
Experience:  35+years experience in automotive repair
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I have a 350 5.7 vortec 1999 engine GMC 3500. Had intermittent

Customer Question

I have a 350 5.7 vortec 1999 engine GMC 3500. Had intermittent firing problems but replaced coil and it ran. Stopped again, replaced pickup coil, modular control on coil, rotor button, coil wire, amd distributor cap. Ran perfect 600 miles. Started on trip died 15 miles from home and is still not firing. Getting fuel and plenty of pressure. Any ideas on what it might be?

Submitted: 7 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 7 years ago.
are you loosing spark on the plug wires when it wont run?how much fuel pressure do you have?
Customer: replied 7 years ago.

I am trying to figure out how to operate this queston answer thing...


No prob with gas. Getting gas but will not fire. First a coil fixed it. Ran fine for a week. Then cuts off 4 times going down the road. I go 70 miles away to fix it and it is running when I get there at truck stop. I go ahead and buy new ignition coil, beside coil, new pickup coil. pickup coil is located in distributor takes 3 minutes to replace, coil wire, distributor cap, rotor button. remember it had started back running and I replaced everything just for future problems. runs home 70 miles, goes on 100 miles run, goes on 600 mile run, parked, started, runs 15 miles shuts off and does not, will no fire!


Checked fuses under hood, all good. Power to new coil. repaced coil with new coil, stil won't work. Took off new parts, put back on old parts same thing. Was running with old parts. What else is left???



Expert:  Tim's Auto Repair replied 7 years ago.


can you tell me how much fuel pressure you psi?


Customer: replied 7 years ago.
Don't know fuel pressure. NO FIRE can't burn it if it was a 1000lbs. Do you now why it is not firing??? That's the answer I am looking for. Gas shoots out like a gusher. I need someone to tell me how to make it fire. New everthing, getting fire to coil.
Expert:  Daves71 replied 7 years ago.

Hi jimmy,if the PCM is not recieving a signal from the crankshaft position sensor you will not have spark.After reading your posts I did not see any reference to the Crank Sensor. If you had a scan tool you could check for crank signal but without one the first step would be to check the wiring at the sensor and if everything looks good(no chafed wires ,plug in good condition,etc) replace the crank sensor and test for spark.Let me know and we can go from there,Thanks,


Customer: replied 7 years ago.

The answer I got was from someone telling me about the Ignition module on the side of the coil. I wrote him back and reminded him of me saying I had replaced everything in the distributor. I did not see a follow up answer and a friend used his hanheld analyzer on Monday 2-8-10 and it read a bad crankshaft position sensor. I bought one and replaced it on Tuesday morning. This was the problem. I posted on the forum what the problem was that day and what fixed it. Now, I get an email from someone with the correct answer after I fix it myself. I was only aware of one answer and it was wrong. The only reason I came back to the forum was to check the answer that Dave wanted pay for. I see the correct answer 5 days after I fixed the ignition problem.

Sorry Dave, you are bad late. I paid the friend for use of his computer and the truck is running fine. My advice for future readers on a fix was plainly written and is posted on this forum on 2-9-10 before your same answer on 2-10-10. Therefore Dave, I don't feel I owe you anything.

Expert:  Daves71 replied 7 years ago.
Thats Fine, glad you got it going.