1998 GMC k1500 5.7 liter auto 4 wheel drive. 176,000 miles no codes. I have owned this vehicle since 2003 starting with 43,00 miles on it.
Sometimes vehicle won't start this happens mostly in morning. Starting fluid does not fire it. If it doesn't start I can go and have another cup of coffee come back out and most of the time it fires up runs good. May run for a week without problem. Have changed ignition module, changed distributor with new cam sensor, tried a diff computer (ECU) from a wrecked vehicle and no difference. Also replace oil pressure sensor which was bad (was told if you pull fuel pump relay and vehicle continues to run it is bad now with new oil pressure sensor it does now kill engine. Put a wire to fuel pump relay to bypass relay and no difference. This has been going on for 2 years. When this problem first showed itself I had it towed to a garage and of course when they got it it fired right up and were unable to diagnose. Another shop had it for a month but started it everyday and couldn't get it to fail (probably because they were not letting it sit for a few days before trying to start). I ordered a new crank sensor OEM but have not put it in. My mechanic is convinced I need a new ignition, says there are contacts in it that can be the problem. I admit I am no mechanic, but I am going to start drinking if I don't figure this out.
You'll never get it fixed buying random parts. Problems like this need hands-on troubleshooting. Not advice over the phone or internet.
- Check for good spark (See our FAQ for more info)
- test the ignition switch
- try a fresh key.
No start troubleshooting from the GM manual...
work through the steps one by one:
Symptom: Hard to start
Symptom:Engine Cranks, But Will Not Run
spark plug check
ignition system check
If it won't start with starting fluid then (assuming the engine cranks and is otherwise OK) you have no ignition. Could be a lot of things from the ignition switch on down the line.
You need to troubleshoot the ignition system when it fails to start. As you found out, randomly throwing parts at the problem doesn't usually produce a good result. (Did you test the parts that you replaced to see if they were bad?)
You can find a repair manual for your vehicle in the link below:
