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Fuel tank overflow - pressure

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Old 06-03-08, 05:42 PM
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Unhappy Fuel tank overflow - pressure

There is always something else...

I never overflow tank at gas station, go by when it shuts off automatically. Drove car for about 20 miles since last fill up.

Today I notice fuel smell at gas tank area, I see fuel drips on a driveway. Then I see that paint is all gone below gas filler hole

I open tank and pressure released with some fuel (I park slightly uphill)

So. What is causing this? What should I do to fix it (besides ruined paint).

Ironically I was researching car re-paint today since shop that painted it did horrible job..

Since summer started (heat) I have already 3 issues:
1. Bumper paint cracked again (2nd repaint with all prep, etc)
2. Rear Spoiler cracked at mount
3. Fuel issue..
Old 06-03-08, 06:44 PM
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Most likely you just need a new fuel tank cap. It's not uncommon to replace those.
Old 06-03-08, 09:40 PM
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Hope so. That was my first idea too. I only worry because last year it passed emissions (they checked cap). But they so cheap I won't even worry about replacing it anyway..

Dealing with pain is another issue now
Old 06-23-12, 04:09 PM
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Just happend to me today. Does anyone know what the definitive fix is for this?
Attached Thumbnails Fuel tank overflow - pressure-gas.jpg  
Old 06-23-12, 04:21 PM
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Did it just randomly overflow like in the OP's post?

Also what mods do you have to the car? (I.E. emissions delete)
Do you still have the charcoal canister?
Any other mods to the factory setup of the fuel tank lines?


I see you are mass. you are getting the heat wave too right?
Old 06-23-12, 05:06 PM
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Omg your paint! Ewwww
Old 06-23-12, 08:18 PM
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I have no airpump or emissions system.
RP Fuel Pump
RX7 Store ultimate fuel system 850/1680
Single turbo
Charcoal Canister is still there
That's it for fuel/emissions mods

I looked through the service manual and think the following components could be responsible:
The Fuel vapor valves
The separator tank
the Charcoal Cannister
one of the check valves

The origionator of this thread thinks his gas cap was the culpret but has not updated us on any resolution. How does a gas tank cap go bad? Could it be that simple?
Old 06-23-12, 10:38 PM
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It's worth swapping out the gas cap, it's not too pricey.

Also, stock the gas cap vents through the evap system into the upper intake manifold. If that is plugged up/capped up that could cause general badness. If that's not being run back into the intake at minimum it should be vented to atmosphere.

Dale
Old 06-25-12, 07:41 AM
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Thanks Dale. I will order the gas cap today. Then I'll top the tank off and let the car sit in the sun. If it doesn't leak, then proplem solved for $20 plus the hundreds it will cost to paint the rear quarter. If it still leaks with the new gas cap, then I will have to trave all the fuel emissions lines and check all components between fuel vapor valves and where it enters the intake.
Old 06-25-12, 08:30 PM
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I pulled the check valve and it works. The solenoid (purge control valve) seems to be bad. I can't get the valve to cycle when I apply direct battery voltage. I also can't get any resistance reading; it is an open circuit. New gas cap is on order. I'll lift the car up tomorrow and pull the charcoal filter; I'm sure there is something wrong there too because it is one of the few things on the car that I haven't had to fix yet...so it must be broken.


I studied the whole system and it's stupid. Fuel vapor valves that flow through check valves into separator tanks, that flow to charcoal canisters, then to a catch tank, through another check valve (just in case) then to a broken solenoid valve and finally into my intake manifold to mess up those AFRs I paid too much money to get tuned just right. My street bike has a way better design. I hole in the filler neck with a rubber hose that dangles from the bottom of the bike dumping the excess fuel that expands from heat on the ground where I want it....not my paint
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