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EOLIVER
04-11-04, 12:52 PM
I have a 1987 AT, after long dirves i've been getting a fuel vapor smell as if it is runnning rich. Anyone have any information on how to check the fuel vapor cannister?

Ken
04-11-04, 03:27 PM
FUNCTIONAL TEST OF CANISTER PURGE VALVE AND TANK PRESSURE CONTROL VALVE

Apply a short length of hose to the lower tube of purge valve, and attempt to blow through it. No air should pass into the canister.

With a hand pump, apply vacuum (15" Hg - 51 kPa) through the control valve tube (upper tube). The diaphragm should hold vacuum for at least 20 seconds, if not, the canister or control valve must be replaced.

CANISTER PURGE SOLENOID

The canister purge is controlled by a solenoid that allows manifold vaccum to purge the canister when de-energized. The ECM supplies a ground to energize the solenoid (purge "OFF").

If the diagnostic test terminal is ungrounded with the engine stopped, or the following is met with the engine running, the purge solenoid is de-energized (purge "ON").

Engine run time after start more than one minute.
Coolant temperature above 75 C (167 F)
Vehicle speed above 2 mph.
Throttle off idle.

jmccloud
04-11-04, 05:09 PM
Had a bad gas fill cap last Dec that caused your same symptoms, gas odor after a 'long' trip (more than 10 or so miles). Defective cap wouldn't hold pressure or vacuum so it was behaving like an old 'vented' cap. Tried a new replacement since that was the easiest and not too expensive. Odor totally gone now.

Edmond
04-11-04, 06:55 PM
Are you getting a running rich code?

Bruce Huey
04-12-04, 05:11 PM
Pretty much same happened to me with my '86 as with jmccloud's gas cap. I had purchased a locking cap that worked fine for a while but I noticed fuel vapor smell a couple of months later. Went back to the stock cap and the smell disappeared. Guess I'll chance a non-locking cap.
B.Huey