‘98 LX 470 gas cap concern

Joined
Oct 20, 2021
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8
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Georgia
I just purchased my first LX 470. I went to refill on gas and as I unscrewed the gas cap, I heard pressure releasing. What is the cause of this? What do I need to look into? This is a stock LX/no mods. It has 252k miles on it. Any advice is appreciated
 
Joined
Oct 14, 2004
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Virginia Beach, VA
That is relatively common, particularly if the tank was toward empty. Unless it is really bad, I wouldn't worry about it. I've owned ~15 90s-2000s toyotas, and they've all done it to some extent.

Also, Welcome! We always love pics if you care to post some.

Cheers!
 
Joined
Oct 21, 2013
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60
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Around Washing D.C.
I just purchased my first LX 470. I went to refill on gas and as I unscrewed the gas cap, I heard pressure releasing. What is the cause of this? What do I need to look into? This is a stock LX/no mods. It has 252k miles on it. Any advice is appreciated
Evap (evaporative emissions) system hadn't purged or vented yet. Pretty common on hot days as some of the fuel (liquid) evaporates into a gas and builds up pressure in your fuel tank. Leave a new style plastic gas can with the new Cali evap s*** on it, it will swell the gas can like a balloon.

The evaporative emissions system is designed to purge (burn off in the engine) or vent it to atmosphere via the charcoal canister (so you don't smell it as much). So pretty much means your system is sealing properly. Now with an EVAP code and pressure in the system, generally means one of the solenoids (vent/purge) isn't opening properly or the canister is clogged.
 
Joined
Jul 19, 2018
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906
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Northwest Montana
How much of a hiss do you hear? A little bit can be considered normal.

Hot summer days, running it hard, climbing in some elevation, and that hiss may be much worse. Seems like a lot of our rigs are plagued with that same issue.
 
Joined
Oct 20, 2021
Messages
8
Location
Georgia
How much of a hiss do you hear? A little bit can be considered normal.

Hot summer days, running it hard, climbing in some elevation, and that hiss may be much worse. Seems like a lot of our rigs are plagued with that same issue.
I guess some would consider this "a normal hiss amount". Similar to opening a new soda bottle. I've never experienced this with a vehicle so I was extremely concerned something was wrong and it was not safe to operate. And it was actually a cooler day. The outside temperature was in the low 60s and I drove it from Greenville SC to Georgia. So I wasn't driving through high elevation. Fuel level was low so maybe that played a factor.
 
Joined
Oct 20, 2021
Messages
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Location
Georgia
That is relatively common, particularly if the tank was toward empty. Unless it is really bad, I wouldn't worry about it. I've owned ~15 90s-2000s toyotas, and they've all done it to some extent.

Also, Welcome! We always love pics if you care to post some.

Chee
That is relatively common, particularly if the tank was toward empty. Unless it is really bad, I wouldn't worry about it. I've owned ~15 90s-2000s toyotas, and they've all done it to some extent.

Also, Welcome! We always love pics if you care to post some.

Cheers!
Thanks man! I’m stoked. Ready to start this build.

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DoughNut

SILVER Star
Joined
Apr 29, 2020
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147
Location
Austin TX
Looks clean. Very nice! I have a 98’. My gas cap has hissed at me since 189k. Just hit 340k. No issues. No check engine lights.

Keep rolling, she will let you know when there’s a issue. $$$ 🤪
 
Joined
Dec 2, 2019
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326
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Oregon
I’m thinking you didn’t hear air escaping, you heard air rushing in to fill the low pressure created by an empty tank.
 
Joined
Oct 20, 2021
Messages
8
Location
Georgia
Any recommendations on where to take this in the Atlanta area for a maintenance inspection? Recent work completed before purchase was TB, WP, Starter, New Heater Rd, and New Radiator. No lights are on. Just want to keep her going for another 252K miles.
 
Joined
Oct 20, 2021
Messages
8
Location
Georgia

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