Idiot light

[Z3PR]

Been battling the damn "Service Engine Soon" light for the last 2 months. It keeps reading the system for the fuel vac. The shop said it can be caused by something as simple as a loose gas cap. They shut the light off each time. We've tried 2 different gas caps, I make sure it's on tight after each fill up. They've had the tank out twice trying too find the problem. This is a small local shop we've been dealing with, so I don't think they have all the equipment the dealership has. I just hate the thought of having too spend $100.00 for the dealership too even look at it but I think I'm going too have too. Car runs fine, but that damn light on the dash drives me bugchit. Car is the 2000 Alero with the 3.4 V6. It only comes on after the 2nd fill up and usely right under 1/2 a tank. Any GM guru's have any idea ???

 

[Thunder]

If a new gas cap didn't fix your problem there is a bunch of other stuff that could be wrong.
Could have a bad vaccum line, bad vapor check valve, Cracked vapor canister, or a faulty purge valve/solonoid, or if your vehicle has one a bad tank pressure sensor.. Trace your lines check the connections at the intake manifold for leaks.
When they had the tank out did they replace the vapor valve or check valve? These valves are either located on the lines on top of the tank or in the fuel cap.
When filling up do you quit filling when the gas nozzle clicks off?
If you keep filling the tank till you cant get any more in it you will suck raw fuel into the charcol canister which will cause problems.
The are tests you can do to diagnose the problem but you need a manual and a vaccume pump.
To check the purge valve WITH THE ENGINE&IGN Off. you can disconnect the line that goes to the canister and try to blow thru the purge valve. If you can blow air thru the purge valve it is bad. It should be closed and allow no air thru it whith the power off.
If you cant fix it yourself its prolly best to take it to a stealership. Be prepaired to pay more than $100 tho. If you have them fix it.

 

[Z3PR]

If a new gas cap didn't fix your problem there is a bunch of other stuff that could be wrong.
Could have a bad vaccum line, bad vapor check valve, Cracked vapor canister, or a faulty purge valve/solonoid, or if your vehicle has one a bad tank pressure sensor.. Trace your lines check the connections at the intake manifold for leaks.
When they had the tank out did they replace the vapor valve or check valve? These valves are either located on the lines on top of the tank or in the fuel cap.
When filling up do you quit filling when the gas nozzle clicks off?
If you keep filling the tank till you cant get any more in it you will suck raw fuel into the charcol canister which will cause problems.
The are tests you can do to diagnose the problem but you need a manual and a vaccume pump.
To check the purge valve WITH THE ENGINE&IGN Off. you can disconnect the line that goes to the canister and try to blow thru the purge valve. If you can blow air thru the purge valve it is bad. It should be closed and allow no air thru it whith the power off.
If you cant fix it yourself its prolly best to take it to a stealership. Be prepaired to pay more than $100 tho. If you have them fix it.

I'm lost with these new FI cars. The $100.00 is just for them too tell me whats wrong with it. I'm sure I'll be looking at $300.00 on up bill too fix it.