Help! 97 won't start, pulling out hair

This is my first post, I have searched but not seen a problem like mine. My girlfriend drove her 1997 c1500 5.7l vortec 5 speed 2WD (200k miles) and parked it. In the morning it would not start. It turns over but will not fire. Furthermore, when turning it over, the motor seemed to 'tighten' up as though it didn't even want to turn. There is no 'security' light and the diagnostic showed no error codes when hooked up the the OBD-II.

Here's the stats: Pressure gage on fuel line reads 66 pounds when cranking. Got spark at the plugs. Turned the engine till #1 compressed, mark on the balancer matched the TDC mark on the timing chain cover and the distributor rotor was pointed at the #1 location, so it appears the timing is OK.

We replaced the fuel pressure regulator, fuel filter, and spark plugs. The distributor cap and rotor are fairly new. We also dropped the exhaust prior to the catalytic converters in case they are clogged. The motor turns more freely now but still won't start. Aside from throwing a timing light on it, I don't know where to go from here.

You all seem to know your Chevy's, any ideas would be greatly appreciated.

I think I would pull the ignition module (in the distributor) and take it to the auto parts store most of them can check it for you.

If you have good fuel and spark the next step is injector pulse.

ON Some the anti theft security system will shut of injector pulse.
Any remote start or add on anti theft stuff?

On turn over good is the battery up good.
The engine needs to crank good to start.
Any signs of oil pressure?
Coolant and oil level good?
If so pull the spark plugs and see if it will crank good?

This may not help but I had the same problem last year on my 98. I had water in the tank. The plugs were wet with drops of water. After 2 days of trying to find the problem my car came down with the same thing. Thats when I pumped some gas into a jar and saw the water. 4 cans of Heet in each got rid of the water. Both car and truck got gas at the same station one day apart. The owner said no one else had the problem. Now I go to a different station.

I think I would pull the ignition module (in the distributor) and take it to the auto parts store most of them can check it for you.

I will try that, thanks.

If you have good fuel and spark the next step is injector pulse.

ON Some the anti theft security system will shut of injector pulse.
Any remote start or add on anti theft stuff?

On turn over good is the battery up good.
The engine needs to crank good to start.
Any signs of oil pressure?
Coolant and oil level good?
If so pull the spark plugs and see if it will crank good?

There is no security dummy light, and I don't even know if the truck has anti-theft, how would I check? No remote start or aftermarket stuff. Should I still check the injector pulse, if so, how do I do that? We've been hooking the battery up to my truck to keep it turning, and it is cranking fast enough to start. I will check on the oil and coolant, but I believe they are fine. The motor turns fine with and without the plugs. Thanks.

Give it a shot of starting fluid in the throttle body after pulling a few plug wires to make sure you are getting fire and the dist gear is really turning.

Tried the crankshaft sensor. Still won't start. Won't start on starter fluid. Getting spark and fuel in the cylinders...any ideas?

Try jumping the oil pressure sw by dist. I remember something about it being in the circuit.

Timing chain jump a tooth?

Spark, compression, and fuel are the three needed things for combustion. You say you have spark, but is it weak? Compression wouldn't keep the whole thing from running since it is specific to each cylinder. You say you have fuel, and have sprayed ether in the intake.
So, that leaves spark. If it is weak, then it may not fire.
You said in the original post that it was starting to turn hard after a bit. That might be hydraulic lock from all the fuel that is being dumped in.

Try an ignition analyzer that will show the spark's quality, pulse, voltage, etc and that will answer that. This is a fairly advanced tool that a shop might only have, but some advanced DVM's have it too.

You might also want to think about the computer. Things can go bad in it, and it won't throw a code if it is a problem with the internal workings. OBD-II only reports when values are out of range from sensors.


Jason

Spark, compression, and fuel are the three needed things for combustion. You say you have spark, but is it weak? Compression wouldn't keep the whole thing from running since it is specific to each cylinder. You say you have fuel, and have sprayed ether in the intake.
So, that leaves spark. If it is weak, then it may not fire.
You said in the original post that it was starting to turn hard after a bit. That might be hydraulic lock from all the fuel that is being dumped in.

Try an ignition analyzer that will show the spark's quality, pulse, voltage, etc and that will answer that. This is a fairly advanced tool that a shop might only have, but some advanced DVM's have it too.

You might also want to think about the computer. Things can go bad in it, and it won't throw a code if it is a problem with the internal workings. OBD-II only reports when values are out of range from sensors.


Jason

Thanks, I'll start looking into these....we tried all the easy fixes...now its time to move on the the more dreadful options...ha!

ok, this is getting strange. It will only start when the driver's side plugs (1, 3, 5, 7) are unplugged or removed. It will fire right up and run fine on the passenger side bank of 4 cylinders. When I reinstall the plugs on the drivers side, it won't start. Any ideas?

MT2500, you seem pretty knowledgable, please tell me you have some insight on the fact that it will only start on one bank when the driver side plugs are unplugged.

You might want to check dist cap and rotor and make sure someone did not cross plugwires.

clean all the battery cables. then charge the battery, then try to start the truck.

ok, this is getting strange. It will only start when the driver's side plugs (1, 3, 5, 7) are unplugged or removed. It will fire right up and run fine on the passenger side bank of 4 cylinders. When I reinstall the plugs on the drivers side, it won't start. Any ideas?

Try installing 1-3-5-7 wires one at a time when you get it started on the other side.
Also I would run a compression test on it and make sure all cylinders have good compression.
Post back compression readings.

And as Gremlin96 said disconnect battery and clean cables and hook up neg cable last when installing cables.
MT

The wire are ran correctly. It will start when I unplug all 4 driver side plugs, but won't when I plug them back in. It also will not start when I unplug the passenger side. I can't think of anything that would not allow it to still start on the 4 passenger side cylinders even when the other side is plugged in.

Try installing 1-3-5-7 wires one at a time when you get it started on the other side.
Also I would run a compression test on it and make sure all cylinders have good compression.
Post back compression readings.

And as Gremlin96 said disconnect battery and clean cables and hook up neg cable last when installing cables.
MT

The cables and battery are good. I will try your idea of installing 1-3-5-7 after start. What is the best way to run a compression test?

Still can't figure out why it wouldn't still start on the 2-4-6-8 cylinders even if there is a problem on the other side.

BTW: Told my girlfriend we should button it back up and she should drive it on 4-cylinders....told her it would be the 'economy mode', she didn't find that very amusing.

The cables and battery are good. I will try your idea of installing 1-3-5-7 after start. What is the best way to run a compression test?

Still can't figure out why it wouldn't still start on the 2-4-6-8 cylinders even if there is a problem on the other side.

BTW: Told my girlfriend we should button it back up and she should drive it on 4-cylinders....told her it would be the 'economy mode', she didn't find that very amusing.

Remove all spark plugs and have some one crank the engine and check each cylinder when cranking engine.

i have heard of fuel pressure regulators going out also leaking and flooding causing them not to crank also pull the dipstick after you try to crank and smell the oil if it smells like gas this may be a possible problem

Got it!!! Camshaft Position Sensor!!! Thanks for everybodies help! Since we replaced everything else as we went through it, she ought to run good as new!

Well, I said computer, but I hade the wrong end!!!


I am glad you found it!.



Jason