Remove Gas Cap, Car Stalls?????
 

Original owner '89TII and never a problem with fuel smell until after sitting at a body shop for @ 6 months 2 years ago, then fuel odor off and on.

Yesterday, took a ride for about two hours, no problem, shut it off, had lunch and started back home, but within 10 minutes gas fumes in the cabin. Drove for a while, then pulled over and removed gas cap, tremendous pressure and car shut off. Finally got it started, drove for a while until the fumes became overbearing, and once again, removed cap to alleviate pressure and car shut off again. Trying to start, backfire in exhaust, then ran fine all the way home, except for the fuel odor. Was going to drive with cap cracked to eliminate the odor which I assumed was coming from the engine compartment, but as soon as the cap is cracked, the car starts to run rough and if not closed all the way the car will stall.

Car all stock except for FD pump, boost controller, G-Force ecu, that's been on there for 15 years.

As I have no idea, just thought I'd get some thoughts before checking the emission system which I'm not looking forward to.

I've experienced similar sporadic problem with the strong fuel smell. Original owner of 90 GXL. Car was parked at IAD airport for several days. After returning from the Daytona 500 last February, I made my way to the parked car, started it and began to drive out of the parking garage. I smelled a very strong fuel smell in the car. I drove home, opened the hood expecting to find some fuel leakage but there was nothing. It was an unseasonably warm day. I'm thinking that maybe it was the higher evaporation rate of the winter fuel on that warm day. Never had a re-occurrence of the problem since. I'm thinking that it might be a good idea to change the charcoal canister since it's the original. Not sure why your car would quit when the gas cap is removed.

Thanks for the reply, but as I neglected to state, the charcoal canister was changed, maybe early last year after the first go round, but sorry to say nothing has changed.

We did have a similar problem with the '88TII we purchased new that on a hot day the fuel smell was terrible and after parking in the garage, the fumes would actually bleed off into the garage through the check/cut valve. So bad we parked the car outside. What happened on the '88 was that the fumes overwhelmed to canister, bleed out the bottom and was sucked into the cabin through the condensate drain. Between this and the trailing plugs that stopped firing, long story short, Mazda bought the car back and I got the '89. Never had a problem with the '89, even on the hottest day with the a/c cranked up. But on the '88, the fuel cap could be cracked to bleed off the fumes and the car would remain running.

Initial thought was that if the solenoid (rats nest) was not working, possibly the buildup of fumes needed to go somewhere, so out the bottom of the canister, but troubling that the car will shut off when the cap is cracked.

Getting too old and have little patience anymore when working on cars, especially when this is such a strange issue, at least to me.

Evap system purge valve would be my educated guess, causing a vacuum leak once you open the gas cap. Try blocking off the vacuum line from the evap canister to intake (or is it throttle body?).

Thanks. Had the problem erupt early last year and actually purchased a new purge valve, but never installed the valve as the fuel smell never returned, until last weekend and at that time never tried to remove the gas cap with the engine running. Now, with all the parts in the garage, should be fun trying to locate the valve.

As soon as the weather warms up here in Jersey I'll take a look. Have the car in a garage that has a heater that can be run when needed, but not too motivated (lazy) to walk up to the back garage and turn it on.

Thanks again