Oldsmobile Repair Questions? Ask a Mechanic for Answers ASAP
2001 Olds Alero, 3.4 V6, cranks over, has fuel pressure, has spark, will start if primed. No problems with security light. Cam position sensor, same ohms reading as new sensor. Is it the PCM or???
GM Tech Cam :
Hello. At anytime during our discussion you need more information or clarification, please reply.
When you say when primed, you mean putting some fuel in the throttle body?
Have you changed the fuel filter anytime recently?
Yes. It has good fuel pressure.
What is the reading and does it hold when you turn the key off?
55 PSI and yes it holds. I have bled it off, turned the key to on, pumped it back up. Remains constant when cranking engine to start.
What is the spark like?
I only checked it at spark plug wire for number 2 cylinder while cranking. It was constant.
Have you checked the injector pulse with a noid light while cranking?
No. What is noid light? Check at wiring harness connector on top of engine to fuel injectors?
A noid light is a small light that plugs in place of the fuel injector and will flash to indicate proper power for opening of the injector.
I can't get to fuel injectors on this car without removing the air plenum. Could I check it at the wiring harness connection coming from the PCM atop the engine with a high quality digital volt meter? (Fluke)
You may be able to yes.
Tell me one thing, Did you get a new tank of fuel prior to this?
No. Car was running fine. Wife drove approx. 25 miles, shut car off, tried to restart after a couple of hours. Car would just crank and not start. It does try to fire on the initial PCM generated injector start fuel, but not after that unless primed.
Does it seem to crank a bit slower than normal?
No. Battery is fine, car cranks over as fast as ever.
When did you last change the spark plugs? and what is the mileage?
Spark plugs and spark plug wires have less than 2,000 miles on them. Changed the fuel pressure regulator at the same time because it was leaking by its diaphragm causing an idle misfire. Car has 127,000 miles on it.
Same time as the wires.
Have you tired an injector flush?
No. Car has had no problems prior to this incident. No lack of power, no hesitation, no acceleration problems or normal starting problems, hot or cold.
Ok, so can you try a bottle of injector flush and see from there? What I suspect is a plugged injector causing a lower flow that needs the vacuum of the engine running to help pull it through.
Can't try bottle of injector flush as car won't start.
I thought you said you can get it running with a spray of fuel in the throttle.
If the crank sensor was bad, I assume the engine wouldn't fire or start at all? But I will change it if I can take an ohm reading to prove it is bad. Sorry for the confusion--engine will only run on the amount of fuel I dump into the air intake between the mass airflow sensor and the throttle body through the vacuum connection to the PCV valve.
Not the PCV valve, the crank case breather tube.
That changes all of this.
So the injectors are not firing.
Is there power to the pink wire at any injector then?
Yes, sorry, the injectors are not firing. That's why I wondered if the PCM was the problem. I have not checked the pink wire because I don't have a wiring diagram.
The pink is a power to each injector.
It gets power when the key is on.
Do you want me to check the pink wire now or contact you later? I'll do this if you can wait a few minutes.
Sure, do it now, I will wait.
Yes. It has 12 V power with key in the on position and during cranking. Now that I know the pink wire is common to all the injectors. I believe I know the color of all the other injector wires and I could ohm them out to see if there is a bad injector, i.e., yellow/black wire for number 6, black/white for number 5. Assume light blue/black is number 4, pink/black is number 3, light green/black is number 2 and black is number 1.
Not all injectors would go at once. So that is why we need to test one with the noid light.
Yes, I know they're sequential. I could check them as we mentioned before with digital meter or purchase a noid light.
I suspect there is a weak signal or something preventing it from running and the crank sensor may be the cause.
After checking & being satisfied with the resistance of the fuel injectors, I decided to prove that I could keep the engine running as long as I could provide it with fuel myself to further prove my assessment/diagnosis that the fuel injectors where not being power/signalled. I did so with my wife cranking it from the driver's seat & I introduced fuel through the port I had previously mentioned & ran the throttle. It ran until I had no more fuel & died. Good news was that the security light was on during this procedure. I reset the passlock system per the owner's manual & other information I gained from a forum on edmonds.com. Now it is running again! You can read more about this system & how to permanently by-pass it on: www.bergerweb.net .
Thanks for your time.