Mechanics

03 WON'T START

2003 Oldsmobile Alero • 6 cylinder FWD Automatic •

We have an 03 Olds Alero. Engine cranks but won't start. Have good fuel pressure at rail, good spark. We spray ether in throttle body and engine starts and runs. Will restart the rest of the day until engine gets cold(overnight) Will not start without ether. When hooked up to scanner and cranking engine there is no cam sensor signal. Once started on ether, signal is present. Help?


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Jctroutman
May 3, 2011.



What is the fuel pressure reading?

Wrenchtech
May 3, 2011.
When initially turning on key, fuel pressure is 60 psi. Once pump is done priming, pressure will drop off to 54 psi. When cranking motor, pressure goes back up to 60 psi.

Tiny
Jctroutman
May 10, 2011.
If you have a scanner look at the CTS annd AIT temps before starting it and see if they match each other.

Wrenchtech
May 10, 2011.
The temp reading on the one is 50 degrees and the other is 52 degrees.

Tiny
Jctroutman
May 10, 2011.
Does that match the temp outside at the time?

Wrenchtech
May 10, 2011.
Don't know for certain but would be a good probability. It was a cool morning.(42 Degrees at 7: 00am)

Tiny
Jctroutman
May 10, 2011.
You have good fuel pressure and good spark. That only leaves injector pulse. You'll need to get a noid light and check the injector pulse when cold to see if you are losing it for some reason. This could be dirty fuel injectors but I kinda doubt it.

Wrenchtech
May 10, 2011.
Unable to access actual injectors without removing intake. However, we were able to probe injector lead with test light. When car won't start, there is no injector pulse. When we spray ether into throttle body, engine fires and injector pulse is present.

Tiny
Jctroutman
May 11, 2011.
An incandescent test light is not a good way to check for pulse. First off, your looking for a ground signal, not a power signals and the but can damage the quad drivers in the PCM. Once you get a little better feel for exactly what is dropping out whether it be power supply or ground pulse and for how long, you can pursue a more specific path. We have probably gone as far as we can in this venue because it's going to take some in depth diagnostics.

Wrenchtech
May 11, 2011.
When we used the test light we first connected to ground on battery and confirmed continuous current on the positive input to injector. When we switched the connector to postive side of battery and tested the ground side of injector there was no pulse in no fire mode until ether was added. Once engine fired, there was pulse on ground side of injector.

Tiny
Jctroutman
May 11, 2011.
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