To test if it is the keyswitch that is my problem can you run the pump from the red terminal in the enginebay to bypass the ignition switch while th eengine is running?

Been thinking about this today and since I can hear it running out of fuel before it shuts down it might be the switch and then it run a few seconds on the remaining pressure in the lines before leaning out with a backfire.


Jan

 

Ok, I did run the pump from the red wire in the engine bay. I could hear it flushing gas through the lines.

It didn't start when doing that. It can be grumpy when in this condition.

I then hooked up my pressure instrument and I got 60PSI when turning ignition on and when the pump shuts down it is 55 PSI.

When then trying to start I got it running and could see that the pressure went down to 50 PSI and it then shut down. Could try a few more times and the same thing every time.

When it will not start I still have 60 PSI at the manifold.


So this would mean a bad regulator?


Thanks


Jan

 

It's doubtful that fuel pressure is causing the problem because it's within specs. If the engine backfires through the throttle body on accelleration, referred to as "induction", it means that the spark plug is firing while its intake valve is open. It's usually caused by ignition timing being advanced too far, or crossfire inside the distributor cap, (weak or broken intake valve spring can cause it too). The PCM has total control over ignition timing, so again, rather doubtful that timing is the problem. Camshaft retard is the alignment of the camshaft position sensor with the camshaft. At the same time the sensor is aligned, the distributor cap is aligned so the terminals are aligned with the rotor when the ignition coil fires. This reduces/eliminates crossfire in the cap. Spec for it is zero degrees, plus or minus 2 degrees. The adjustment is done by viewing camshaft retard on a scan tool, while rotating the distributor. The adjustment does not affect ignition timing on this engine, (timing pulse originates at the crankshaft position sensor). I would suggest having a shop check camshaft retard, and make sure you're using an AC Delco distributor cap and rotor.

The ignition switch controls several different circuits through several different sets of contacts. If the switch is messing up, it's likely more than just one electrical component or circuit would be affected. We're not ruling it out as a possibility at this point though.

EDIT: It might be a problem with the Passlock system. If it detects a "theft situation", the PCM will shut off the injectors, fuel pressure will drop, and the engine will stall. Is the "Security" light on the dash illuminated?

 

My woes continues....

I have now changed the ignition switch and it will still not start. I can hear the pump running. The first time I tried to start I couldn't hear the pump. I did the Passlock Re-Learn procedure.

There is talk about some security light, but I can't see any.

Car is a 97 LS, when I turn ignition on there are four lights that stays on for ever. It's the Battery, ABS, Engine Service Soon and Check Gauges. None of the turns off as long as ignition is on.

Do I need a Tech-2 to fix this?


Thanks


Jan

 

Do you have a good blue, (not orange) spark on each plug wire at each spark plug while cranking?

 

I just went out to check that, 11pm over here :-)

I connected the spark tester and when I cranked now it tried to start. On cyl 1 which I tested the spark looked white. It started to run so I connected that cylinder and it started! What I could see on the tester I had to crank for a while before any sparks were seen and when they showed up it tried to fire. So the sparks were not there from the moment I started cranking.

Unfortunately it behaves as it did before I changed the switch. It run for a short while and then shuts off. And after that it is dead.


Thanks


Jan

 

So the spark is nonexistant or erratic at the spark plug. Remove the coil wire from the distributor cap and install the spark tester on the coil wire. See if the results are the same. If the results are the same, the next step will be to check voltage and ground pulse at the ignition coil. If it shows good spark immediately & continuously when you crank it, the problem is either the distributor cap, the rotor, or the plug wire(s). Post your results.

 

I did some more testing with the sparkplug tester.

Car has been still for a day with out any tries to start it.

From the coil I have spark and on a couple of cylinders, i didn't try all.

Hook up the cables and it comes to life for a short while, just a few seconds.

The trying with the sparktester and now it is dead, no spark from the coil. So something shuts off the ignition to the coil. Could this be the Passlock?

Or, I start to suspect the aftermarket alarm that was mounted 15 years ago in this car. It's a killer alarm and there isn't any wiring diagrams of it. I'll try to follow the wires and disconnect it. Most of the cables have the same color on it to make it harder to hot wire.


Thanks


Jan

 

Passlock shuts off the injectors, not the ignition. Ah ha, but now we have new information to deal with! VERY possible the aftermarket alarm is messing with the ignition. Depending on the way the circuitry was designed, it could interupt the starter, the ignition, or the fuel pump. Disconnect and remove all wiring associated with the alarm, and reconnect any vehicle wires that were cut. Some alarms require cutting a vehicle wire and connecting two wires from the alarm module to the cut ends of the vehicle harness. This could very well explain what's causing your erratic issue.

EDIT: When you reconnect any cut wires, solder the connections, don't use crimp connectors, (they are very unreliable).

 

Feels like I'm back to square one...


Jan