Pre-Winter maintenance---HELP/INPUT NEEDED '02 LS V-8

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cammerfe

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I made a list of things to do for pre-cold-weather maintenance. Then I went out earlier today to get things such as a set of plugs, fluids, and so on. I was motivated by not only the season but also an incident last spring. We had a cold snap and for several days the car simply wouldn't start. I let it be for several days and when next I tried it, it started right up and has run just fine ever since. I supposed a frozen fuel line. The car (bought new) has always been ultra-reliable.

Here's the problem:

I went out this morning to do the errands and, in the store parking lot it suddenly quit. It refused to re-start and I had it brought home on a roll-back. Since I could hear the fuel pump momentarily hum when the key is turned on, I supposed the fuel filter to be plugged. ( Put in a race-style aircraft filter several years ago. The body un-screws so it's possible to see what might be in it.) It's absolutely clean inside. So I'm stumped. When I first tried to re-start it in the parking lot I had what seemed to be random plugs firing so I'm guessing that the ignition isn't completely dead.

Can anyone give me a flow chart of diagnostic tests that are do-able? I have a digital VOM as a testing tool. Since I moved, my better stuff is mostly packed away but I suppose I can get anything I might need. I have access to a BFH if necessary.

Yesterday the engine would go right past 6K during passing on the X-way.

There have been no codes thrown.

Any help much appreciated.

KS
 
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Find out if fuel problem. turn on key, (hear fuel pump) uncover fuel shrader valve, and with rag over outlet, depress the pin in the valve to see if there is a good spurt of fuel. (The attempt to start randomly is a good indicator of lack of sufficient fuel). Try that and report.
 
Thanks for the suggestion, Sub. I removed the Shrader valve from the fuel rail some years ago and used the fitting as the connection point for a direct reading fuel pressure gauge. The gauge shows forty pounds of pressure.

And Joe, I didn't realize that a dirty MAF would actually keep the engine from running. I was intending to clean it as part of my maintenance. I hope that solves the problem. More tomorrow.

KS
 
cammerfe said:
...And Joe, I didn't realize that a dirty MAF would actually keep the engine from running. I was intending to clean it as part of my maintenance. I hope that solves the problem. More tomorrow.

KS
Click to expand...

Yes, I found this out the hard way. It'll make it seem like it is trying to fire on some cylinders, but it won't catch and run. The PCM won't inject fuel if it doesn't think that air is going into the engine. When this happens, you can unplug the MAF and the PCM will go into failure effects management and the engine will start and run.
 
It's raining here this afternoon and I still have to finish up in the wheelhouse and get the car back on the ground. I'll try the un-plug and test suggested by Joe tomorrow morning and go from there.

My most sincere thanks for the very helpful input here!

KS
 
UPDATE--------

I got the car back on the tires and tried the un-plug suggested by Joe. NADA

Removed the MAF sensor and closely examined the little wire element. It looked just fine but I gave it a good spray of cleaner. Then while waiting, I put a good spray of starting fluid into the intake duct. Still nothing. No hint of trying to fire.

I'm back where I started. Long ago a shot of gas in the carburetor would help diagnose fuel problems and holding the coil wire close to a ground would tell you about ignition. There are no codes showing but it simply shows no sign of firing.

Any suggestion of a diagnostic flow chart or where to find one would be very much appreciated. I did try searching but no joy.

THANX!!!

KS
 
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Check for power at the front fuse box.
Check for power at the coils.
Check crankshaft sensor. (should be getting a code, though)
Check camshaft sensor. (should be getting a code, though)
Check compression.
 
cammerfe said:
When I first tried to re-start it in the parking lot I had what seemed to be random plugs firing so I'm guessing that the ignition isn't completely dead.
Click to expand...

Just the first time? Is it still doing this? I guess I don't get your description of exactly what its doing...
 
So it is turning over, correct? Have you checked the fuse for the coils? Mine popped when a bracket sliced/shorted a wire while running. I was reinstalling the cabin filter box and when it finally squeezed past the strut brace, it pushed the shock tower wiring harness bracket into the ignition wire on cyl#8
 
One more time thank you for your suggestions. More tomorrow although I'm going in two directions. I'm also re-arranging my storage unit to make tools more easily accessible.

KS
 
I know there was no mention of any parking lot "incidents" or "jolts", BUT
for what it's worth, it wouldn't hurt to check this just to be sure it's off the list.



RESETTING THE FUEL PUMP SHUT-OFF SWITCH FUEL

The fuel pump shut-off switch is a device intended to stop the electric
fuel pump when your vehicle has been involved in a substantial jolt.
After a collision, if the engine cranks but does not start, the fuel pump
shut-off switch may have been activated.


The fuel pump shut-off switch is located in the driver’s foot well,
behind the kick panel. The reset button (RED) for the fuel pump
shut-off switch is accessible through an opening in the kick panel.
 
On the last winter starting problem... gasoline freezes at -40F to -50F, so unless you have water in the fuel this would not be an issue. Once you figure out why it isn't running now, you can put some Heat in the fuel tank, then try to run it almost dry before refilling to eliminate any possibility of water in the fuel.

I would far more likely think that the problem is a worn out battery as when it gets cold a battery's available amperage drops. In fact, this is why batteries have two separate amperage readings, with the CCA (Cold Cranking Amps) being a couple hundred amps lower than the regular temp amperage. The starter will draw several hundred amps by itself while the rest of the car only needs about 20-30 amps to run everything, so a battery can run everything but the starter and still be bad. The dealer will have the correct battery and the price isn't too far off from what a discount store wants for it plus the dealer battery will be guaranteed to have the necessary vent. In fact, a new battery may fix your current problem with not starting, as a bad battery does funny stuff to the LS including messing with the computer. Plus, if the battery is bad (and the only way to check it correctly is a deep cycle test which takes 30 minutes to run) it will kill the alternator in short order. In fact, I'd have to wonder if the alternator isn't already damaged if the battery was bad last winter.
 
Since the fuel pump runs momentarily with a key-'on' and the pressure gauge shows 40+ PSI, I know there's fuel to the rails.

The battery is less than a year old and has been tested. The volt meter shows 14 volts. Later today I'll check the fuse for the ignition.

After the first several minutes there has been no sign of any cylinder firing. I gave it a shot of starting fluid and---nothing.

Even if there were to be a problem with power to the injectors I'd think there'd be momentary firing because of the ether.

Therefore a lack of spark seems the most likely area for exploration.

Your comments are very much appreciated.

KS

EDIT TO ADD---

The schematics of the fuse boxes available on the internet leave a lot to be desired. And working in the dark and the rain don't help either. The COP fuse was blown. Runs fine after replacement.

But something momentary DID happen. It ran very poorly for perhaps 10-15 seconds before stalling. Attempting a re-start resulted in random attempts for cylinders to fire over a period of several minutes. But now everything is serene. Any further thoughts??

KS
 
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Bump asking for input as to the precipitating factors in this experience. Comments much appreciated and THANKS in advance!

KS
 
I suppose it could be a component (like one of the COPs), but I think that it's more likely to be a nicked wire somewhere. I'll check the schematics that I have tonight (if I have time and if I remember) to see what all is on that fuse. First guess would be to look at the common wire to the COPs at the back of the engine where it exits each COP cover.
 
My gen I wiring diagrams aren't as good as the gen II ones, so this comes from looking at both.
The fuse for the COPs is F1.12. It's a 10A on gen I and a 15A on gen II (Gen I diagram may be wrong).
The fuse feeds a green/black wire on gen I and a green/blue on gen II. It goes to the back of the engine and runs the passenger side, changing color slightly as it goes to each coil. Green/yellow, green/blue, green/red, green/black. A green/red wire goes from the passenger side to the driver's side (green/light blue on gen II). From there it goes to the driver's side coils, green/orange, green/white, green/yellow, green/blue. It also goes to the two noise filter capacitors (one on each side), green/blue. It doesn't show any other connections for fuse F1.12.
 
One more time you give help that's otherwise simply not available. Fuse 12 was the one that was blown and from the factory it WAS a red 10 amp. I'll be changing plugs this weekend as part of the seasonal touch-up and will pay close attention to the wires you've mentioned.

KS
 
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