89 Truck -- problem with gas odor at high altitudes

Greetings from one of the many long-time NG readers. I have an unusual problem with my 1989 Toyota truck (4WD, 5-sp, 3.0 V6, 124K miles) I was hoping you all could help me with.

The truck lives and is a daily driver in the southern California area, at about 1,500 ft. elevation. About once or twice a year I drive it to the Colorado mountains to visit my lovely daughter who lives in Gunnison (elevation 7,300 ft.), and whenever I spend more than about a day or two at the higher elevations I start getting a very strong odor of gasoline (sometimes so strong I'm afraid of anyone even walking by with a cigarette). However, as soon as I come back down to lower elevations, the odor immediately goes away. The time period is significant, as it does this only after the truck has been at altitude for at least one or two days. I live close to the mountains here in So Cal, and if I drive it up to the mountains (6-7,000 ft) and back in the same day, then there's no odor.

My first thought was the EVAP charcoal canister, but when I asked about it at the dealer, he said he didn't think that would be the problem - that the canisters generally don't go bad on these trucks - and that more likely it was just a leaky fuel hose somewhere. If that's the case, then why wouldn't I be getting an odor all the time? (And besides, he quoted me a price of something like $250+ for the canister.) I've been all over the fuel system and hoses, but have not been able to find anything obvious.

So any ideas why I would get a strong gas odor only at high altitudes? I would appreciate any advice you can offer, as I am scheduled for another trip up there at the end of this month, and would really like to not have to worry about this.

Thanks,

JimC in Redlands

Reply to
JimC
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Silly Wild-ass Guess (and you'd be amazed at my guessing abilities):

The Reid Vapor Pressure of California Low Emissions Fuel with Ethanol and other voodoo chemistry added, made for sale and use at low altitudes, is too high for high altitudes. When you get into the mountains the pressure buildup in the tank when the vehicle sits for long periods is higher than the evap system (IE the charcoal canister) can absorb and it vents.

If you drive a lot while you're at altitude, the vacuum of removing the fuel from the tank and the evaporative emissions system is enough to keep up with the vapor generation rate.

"That's my story and I'm sticking with it." ;-P

(IOW Heck if I know, but that makes as much sense as anything...)

Practical Experiment: Plan your trip so the truck is on EMPTY when you arrive, and fill up with a tank of Gunnison CO Gasoline that is formulated for the high altitude with the right RVP for the area. Better yet, run low when you start getting close and get a half-tank of the local brew when you're a few hours out (to flush out the California gas) then fill it up when you arrive.

Let the truck sit the same time you usually do, and see if you still get the vapor venting problem.

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Reply to
Bruce L. Bergman

and if Bruce is right u might just pop open your filler cap on a daily (or more often) basis while up that high and and see if that fixes it.

Reply to
JeB

Gentlemen,

Thanks for the advice -- I will definitely take note of the gas gauge, fuel type, and fuel cap, and see if that makes any difference. I do seem to recall, however, that on previous trips the odor persisted long after I had refilled out-of-state and had been at altitude for several days. So I'm still wondering if there might yet be something else that I'm overlooking.

Would still appreciate any and all ideas you'all might have.

Thanks again...

Reply to
JimC

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