Hi,

I have been chasing a strong fuel smell for years on 1988 Firebird GTA with 5.7 engine. I know where it is coming from. It is coming from the vapor line from the fuel tank. I have capped this line and there is no fuel smell after driving. This line is connected to the solenoid on the vapor canister. The issue is that the solenoid is not activating to allow the fumes to be sucked into the throttle body. I used a paper clip in the ALDL port to test the solenoid and connector. It activates fine. I also probed each pin on connector with multimeter and test light. The light comes on when I connect to both pins. I get a light when I connect to + pin and chassis ground. I also get continuity from ground pin to chassis ground. Per service manual, this proves wires are good and solenoid is good as it activates. However, with engine running and meeting these conditions per service manual,

Circuit Description:
Canister purge is controlled by a solenoid that allows manifold vacuum to purge the canister when deenergized.
The ECM supplies a ground to energize the solenoid (purge "ON").
If the diagnostic test terminal is grounded, with the engine stopped, or the following conditions are met
with the engine running, the purge solenoid will be energized (purge "ON").
@ Engine run time after start more than 1 minute.
@ Coolant temperature above 75°C.
@ Vehicle speed above 15 mph.
@ Throttle position is above idle.

there is never ground enabled by the ECM as test light never comes on. Could this be an indication of a bad ECM? I checked ECM and it is not original. It has been replaced but cannot determine its age. If it is bad, I have been unable to find replacement as it shows Out of stock everywhere. ECM is: 1227165 but I understand that there are other ECM models which will work like 19367537.

Any pointers or confirmation of my diagnosis?

Thanks

 

The ECM may have a problem, or the MEMCAL may not have the purge enabled.

 

You're saying you're conducting the test with the engine running. Are you driving it while checking? The manual says...

or the following conditions are met
with the engine running, the purge solenoid will be energized (purge "ON").
@ Engine run time after start more than 1 minute.
@ Coolant temperature above 75°C.
@ Vehicle speed above 15 mph.
@ Throttle position is above idle.

The car has to be moving at >15 mph in order for the ECM to activate it.

Otherwise, if you're doing the test in your driveway, then the engine has to be stopped.

The ECM supplies a ground to energize the solenoid (purge "ON").
If the diagnostic test terminal is grounded, with the engine stopped,

If the solenoid and ECM end up checking out ok, then it could be the canister itself is in need of replacement as the charcoal inside may be saturated. Or if you're sufficiently handy, you can replace the charcoal (there are threads on this site about how to do it... I actually did it myself as well).