97 TAHOE 5.7L VORTEC WON'T START...GM Merlin ideas?

[mwhughes]

The engine turns over but won't start. Therefore we did a new distributor, new coil, new fuel pump, new fuel filter, valve job and timing chain , all done at the same time. Spark plug wires have been checked and are in the correct firing order. Cam shaft sensor and Crank shaft sensor are both good. The engine has been timed according to protocol for timing a non-running engine. Good fuel pressure. Good spark. It still won't run. The intitial problem was the engine turned over but wouldn't start. All this work done and, the engine turns over but won't start. 130,000 miles. Any ideas? Could the computer be bad and how do I check that? Last resort, a trip to the dealer via a flatbed.

thanx,
Michael

[aero246]

Check your timing chain. It may be broken.

[mwhughes]

Hey aero246:

Thanx for the reply, but we replaced the timing chain as well. That has been double checked to this point. More importanlty, the crank shaft sensor has also been checked.

Originally Posted by mwhughes

Therefore we did a new distributor, new coil, new fuel pump, new fuel filter, valve job and timing chain , all done at the same time.

thanx,
Michael

[EmesiS]

Do you hear your fuel pump starting up when you turn the ignition key? If not check the fuel pump relay, this is something simple but it may have been missed. If you suspect that might be it, take it out and tap it on a hard surface to unstick the contacts and put it back in and try to start again. This happened to me because I would not hear the fuel pump kick in before I started the engine. And of course the first thing a dealer wants to do is replace the fuel pump. So I tried a little troubleshooting myself which started with the fuel filter and then the relay. Hope this helps.

[GMMerlin]

Originally Posted by mwhughes

The engine turns over but won't start. Therefore we did a new distributor, new coil, new fuel pump, new fuel filter, valve job and timing chain , all done at the same time. Spark plug wires have been checked and are in the correct firing order. Cam shaft sensor and Crank shaft sensor are both good. The engine has been timed according to protocol for timing a non-running engine. Good fuel pressure. Good spark. It still won't run. The intitial problem was the engine turned over but wouldn't start. All this work done and, the engine turns over but won't start. 130,000 miles. Any ideas? Could the computer be bad and how do I check that? Last resort, a trip to the dealer via a flatbed.

thanx,
Michael

Do you have fuel pressure (around 60-65 psi key on engine off)?
I would venture to say if you have fuel pressure and spark, I would look towards the injectors as the cause of your problem.
2 things could be happening.
1. the injectors are not being triggered by the PCM..causes, no power to the injectors or the PCM is not grounding the injector
2. There is a possibility that if you have spark, fuel pressure and injector pulse then the injectors are stuck shut. this system uses a poppet valve on the end of the injector to provide fuel..the poppet is a mechanical ball and seat injector that can stick.

[MyHoe]

I had the same problem, It turned out to be my Fuel Pump. The damn thing was 200 bucks just for the pump. You also need PLASTIC line tool. The metal one from auto parts store didnt work. I hoped it was the Relay but no luck, had to come out of pocket.

[Tagahoe]

I have that same problem, but mine sometimes starts up fine. I can drive it around, park it, go to start it up the next day and it wont start, then a few hours later it will start. what the hell is that? I've done a tune-up, fuel pump is new and working, fuel filter is new, and changed the ignition coil, any ideas?

[Tagahoe]

any ideas anyone. went to start it this morning to take it to get check, and sure enough it wouldnt start, even though it started all lastnight. damn it!

[Tagahoe]

Well i heard it is the Fuel Pressure Regulator. Anyone ever change one out?

[Tagahoe]

well i change the fuel pressure regualtor and everything worked fine, until today. i went to start it after driving it all day, and it wouldnt turnover again. what the hell is it?

[GMMerlin]

Originally Posted by Tagahoe

well i change the fuel pressure regualtor and everything worked fine, until today. i went to start it after driving it all day, and it wouldnt turnover again. what the hell is it?

So what is going on? Is this a spins and no start or a will not turn over problem?

[Tagahoe]

I guess I have to say a spin and no start, cause it is turning over, just not starting. Like I said, sometimes it starts fine and runs fine.

[krunt]

I had a problem like that. It turned out the Passloc was kicking in. Check to see if the security light is flashing with the key on after you try to start. If it is flashing leave the key on until it stops thenturn it off and try to start it. I read something about these going when the wires rub underneath the dash. I sent mine out and had to replace a module in the aftermarket alarm. No problems since X

[Tagahoe]

Nope, its not flashing, but i tried it anyway, and nothing.

[ponchonutty]

Had a desperate person call stating their '98 Tahoe won't start. It will crank but not fire. Said alarm shop wouldn't look at it because they said they knew it wasn't the alarm/remote start(Viper 781xp).
Dealer said it had to be the aftermarket items and said to remove them first.

So, I tried to walk him through some things over the phone. I mention basically what all was said above. He said he had replaced the fuelpump a few months ago and the truck ran fine. Then about 6 weeks later, it started chucking then wouldn't restart. He said he replaced the fuelpump again along with the fuel filter but still no fire. He later on replaced the fuelpump relay but same outcome.

After he towed it in I began to pick it apart. I looked at the pump relay and even jumpered the wire but it never came on. Looked at the PK2 light on the dash and it behave normally. So, I dropped the tank because I metered the gray wire at the pump relay but it didn't show any ground. Took out the pump and inspected. It was obviously new. I rigged the pump with my 12v drill battery and it worked. Checked the connector on the pump and it metered fine. Looked at the plug/harness that goes from the relay to the pump. The gray wire was fine but noticed the black ground wire was pushed back. Replaced the pin and wire, all is fine now.