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Dripping fuel while driving.

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Old May 18, 2025 | 09:59 AM
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MarkyMark425's Avatar
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From: Bayshore, NY
Car: 1991 Pontiac Trans Am GTA
Engine: 350
Transmission: 700R4
Axle/Gears: Standard
Dripping fuel while driving.

I drive my Trans Am locally. When I go on long drives about an hour drive, I start to smell fuel. I look in the side mirror and I see a trail of fuel under the car. I watch my gas gauge drop. I replaced the vent valve and the gas cap thinking it was that. I filled up a full tank of gas, drove home smelled fuel looked under but no spots. Anyone knows what it is


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Old May 18, 2025 | 10:10 AM
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ULTM8Z's Avatar
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Re: Dripping fuel while driving.

What about all the vent hoses? Are they still the original hoses? Could be dried out and cracked.
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Old May 18, 2025 | 10:14 AM
  #3  
MarkyMark425's Avatar
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From: Bayshore, NY
Car: 1991 Pontiac Trans Am GTA
Engine: 350
Transmission: 700R4
Axle/Gears: Standard
Re: Dripping fuel while driving.

@Supreme Member new fuel lines front to back replaced when I did the engine swap. Evil energy fuel lines new filter and new holley fuel sytem in tank.
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Old May 19, 2025 | 12:53 PM
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From: South FL
Car: 1989 Formula T-Top
Engine: 350 TPI, twin turbo
Transmission: 700R4
Axle/Gears: 3.23
Re: Dripping fuel while driving.

Suggest double checking the rubber lines at the tank are connected in the right order. I had a full tank once and drove 70 highway miles no problem. When I stopped at the car show (!) fuel started pouring out of the vent valve. Turns out the vent hose was reversed with the return hose. Return line being at bottom of tank pushed fuel out when pressure built. Unscrewing the cap and the huge hiss release of pressure was the clue I was a dumbass when I reattached the lines after the pump swap. Not clear why pressure built, I would think as fuel is removed there would be suction under those circumstances.
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Old May 19, 2025 | 06:05 PM
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Car: '89 Firebird
Engine: 7.0L
Transmission: T56
Re: Dripping fuel while driving.

A leak that big is as easy to find as a faucet left on in the house. All you have to do is actually look for it. If you haven't found it yet then you're not even trying.
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Old May 19, 2025 | 08:06 PM
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From: Meriden, CT 06451
Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Dripping fuel while driving.

Originally Posted by QwkTrip
A leak that big is as easy to find as a faucet left on in the house. All you have to do is actually look for it. If you haven't found it yet then you're not even trying.
Or take a flame to the fuel on the ground and follow where it originates.
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Old May 19, 2025 | 08:07 PM
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From: www.nythirdgen.com
Car: 1987 IROC-Z
Engine: 350 TPI
Transmission: 700R Auto
Re: Dripping fuel while driving.

Originally Posted by QwkTrip
A leak that big is as easy to find as a faucet left on in the house. All you have to do is actually look for it. If you haven't found it yet then you're not even trying.
That was my feeling as well. The tank vent valve was clogged so the shop figured that was the only issue. I am thinking the fuel lines not being connected correctly is the issue. Does anyone have a picture or a diagram of the correct connection?
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Old May 19, 2025 | 08:43 PM
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From: Il
Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: Dripping fuel while driving.

Cracked neck, rusty tank or bad seal on sending unit.
You have some work ahead
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Old May 20, 2025 | 12:34 AM
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From: Western WA
Car: 1989 Firebird
Engine: 2.8 V6
Transmission: T-5
Re: Dripping fuel while driving.

When you did the swap, did you convert to AN fittings? Possible one of those is leaking. I used the Evil Energy kit when I put the 4th gen tank in, and remember it being very specific about putting the hose ends together to prevent leaks.
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