EM light flickering and trouble starting

[Spectralcav]

The old Cavalier is normally so reliable but now has a problem with the engine randomly cutting out and having trouble starting (intermittently).

I've tried flashing the codes using the paperclip test, but the EM light sometimes flashes as normal but often flickers which makes it very difficult to read any codes. Even without shorting the pins on the diagnostic plug, the EM light also often flickers when the ignition is turned on (before the engine is started) and sometimes goes out altogether.

The engine sometimes starts OK and sounds fine when it's running, but it can cut out at any moment so is currently not driveable.

Does anyone have any ideas what the problem could be? I'm thinking a broken wire somewhere or the ECU has a problem. Any other thought would be appreciated

Thank you

[TurboDan]

Could be a loose wire somewhere or bad earth.

Also check the fuel pump relay hasnt got wet as i had this problem and it turned out to be that.

[Spectralcav]

Could be a loose wire somewhere or bad earth.

Also check the fuel pump relay hasnt got wet as i had this problem and it turned out to be that.

Thanks Dan.

The fuel pump relay does get a bit damp - I tried a spare fuel pump relay I had knocking about but no difference but that was from a car with a leak in the same area!

I'll try cleaning the corroded contacts on the original relay and see if that does anything.

[Spectralcav]

Cleaned the contacts on the relay and fitted it.

The EM light was mostly steady; still flickering a little bit, but if I put pressure on the wires to the relay's connector plug the light is steady and the car doesn't seem to show any signs of wanting to cut out.

I'll clean the contacts on the plug connector and that should sort it out (fingers crossed)

[TurboDan]

When my relay was wet and knackered it actually looked fine from the outside just some tiny specks of water on the pins but once you opened up the relay i found mine was soaked inside and thats why it wasnt working. It was also going rusty due to the water and so i ended up getting another one and it sorted it.

[Spectralcav]

A new relay is on it's way to me - cleaning the connectors etc didn't solve the problem after all, despite early promise

Really hope the new relay sorts it out - I hate messing about with wiring!

[Spectralcav]

Damn! New relay didn't work

So I guess it's a wiring fault - not good!

Just a thought; is there any chance that the fuel pump itself may be faulty, or the wiring at the fuel pump end - could that possibly cause a flickering EM light?

Any ideas?

PS - I did manage to flash the code as Code 32 - Fuel pump relay - before the EM light started flickering again. The new relay is a brand new genuine part. I also tried another relay which I was holding as a spare so I don't think the relay itself is the problem unless I'm exceptionally unlucky...

[TurboDan]

Hmmm not sure like you say it could be wiring. I would try and trace back the wires from the fuel pump relay and see if there are any breaks. Is anything else damp? Ecu?

[saucy_begger]

Your problem sounds like the crank/camshaft sensor failing