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  1. #1
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    Fuel Tank Screw Cap/Seal Leak Question

    I did a Walbro modification a while back and recently the venturi hose slipped off so I had to remove the fuel pump to fix. After reinstalling it, my fuel gage wasn't working correctly so I took it back apart and reinstalled. Since that second reinstall, I've had a fuel leak at the cap/seal whenever I fill my tank. My question is, judging by my fuel sensor (which did start working again after the second install), I can get another 3-4 gallons in the tank...but if the fuel is at the top of the tank where the screw cap is, wouldn't that be full or does the fuel disperse somewhere? Trying to determine if my sensor is wrong or if it does disperse.

    Last night I went to do a 50/50 E85 fill up and the fuel gage said I had 60 miles left on my tank. I was going to do a 14 gallon fill. I got 7 gallons of E85 in when I started to get a slight fuel drip from under the car. I looked at the cap under the seat and that is where the fuel was definately coming from and running down the tank and onto the ground. The pump never clicked so it wasn't full....why then was the fuel all the way at the cap?

    Just trying to see if the tank is full or not when fuel is at the cap. LOL Sorry for the loooong lead in... Click here to enlarge

    Robc
    JB4 G5, 455 LPFP, HFS-4 meth kit, BMS OCC, VM 6466 ST, RB valve, BMS DCI, 3" AR Dps, Custom OC W/ SS lines, ER FMIC, ER CP W/HKS BOV, M3 control arms, M3 guide rods, M3 upper links, M3 front & rear sway-bars, HPA rear toe arms, Wavetrac LSD, HPF Gen 2 exhaust DEFIV kit, KW clubsport, Delrin solid subframe bushings, stoptech rotors, Rogue Tranny Mounts, 1M bumper, M3 CF hood, MORR VS8.2 rims 245/295

  2. #2
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    bump

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    1 out of 1 members liked this post. Yes Reputation No
    I know there is a drain below the cap that allows excess fuel to drain near the rear passenger side wheel when there is overflow. Not to be captain obvious, but if you are over flowing, I would assume you have to be full.
    Click here to enlarge
    PTF Tuned Cobb Stage 2+ | H&R / Koni Sport | BBS LM

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    Click here to enlarge Originally Posted by JStang Click here to enlarge
    I know there is a drain below the cap that allows excess fuel to drain near the rear passenger side wheel when there is overflow. Not to be captain obvious, but if you are over flowing, I would assume you have to be full.
    great info.. I know there is a spot right by the cap that has a area if there is over flow it will leak by the passenger side if there is a leak, but why is the gas getting past the seal? Usually if you over flow it will come out of the filler neck before the tank. Also why did the gas pump not "click off" when it was full what tells the nozzle to stop pumping....that must be a issue with my situation. If there is a vent in the cap for over flow it would come out with sloshing abs would also be a Snell wouldn't there. My car has a smell of gas so I assume there is a seal leaking.
    JB4 G5, 455 LPFP, HFS-4 meth kit, BMS OCC, VM 6466 ST, RB valve, BMS DCI, 3" AR Dps, Custom OC W/ SS lines, ER FMIC, ER CP W/HKS BOV, M3 control arms, M3 guide rods, M3 upper links, M3 front & rear sway-bars, HPA rear toe arms, Wavetrac LSD, HPF Gen 2 exhaust DEFIV kit, KW clubsport, Delrin solid subframe bushings, stoptech rotors, Rogue Tranny Mounts, 1M bumper, M3 CF hood, MORR VS8.2 rims 245/295

  5. #5
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    Click here to enlarge Originally Posted by JStang Click here to enlarge
    I know there is a drain below the cap that allows excess fuel to drain near the rear passenger side wheel when there is overflow. Not to be captain obvious, but if you are over flowing, I would assume you have to be full.
    just to be clear, the leak I am having is at the fuel tank cap NOT the gas cap.....is this what you're referring to?
    JB4 G5, 455 LPFP, HFS-4 meth kit, BMS OCC, VM 6466 ST, RB valve, BMS DCI, 3" AR Dps, Custom OC W/ SS lines, ER FMIC, ER CP W/HKS BOV, M3 control arms, M3 guide rods, M3 upper links, M3 front & rear sway-bars, HPA rear toe arms, Wavetrac LSD, HPF Gen 2 exhaust DEFIV kit, KW clubsport, Delrin solid subframe bushings, stoptech rotors, Rogue Tranny Mounts, 1M bumper, M3 CF hood, MORR VS8.2 rims 245/295

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    I guess I misunderstood. I have overfilled before and the area around the cap filled up a little and the excess fuel dripped down by the rear passenger wheel. As I saw the excess gas disappear I assumed it was going into the tank but then saw it exiting on the ground.
    Click here to enlarge
    PTF Tuned Cobb Stage 2+ | H&R / Koni Sport | BBS LM

  7. #7
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    Click here to enlarge Originally Posted by JStang Click here to enlarge
    I guess I misunderstood. I have overfilled before and the area around the cap filled up a little and the excess fuel dripped down by the rear passenger wheel. As I saw the excess gas disappear I assumed it was going into the tank but then saw it exiting on the ground.
    I know exactly
    what your are saying. Yeah mine is a bit further down.
    JB4 G5, 455 LPFP, HFS-4 meth kit, BMS OCC, VM 6466 ST, RB valve, BMS DCI, 3" AR Dps, Custom OC W/ SS lines, ER FMIC, ER CP W/HKS BOV, M3 control arms, M3 guide rods, M3 upper links, M3 front & rear sway-bars, HPA rear toe arms, Wavetrac LSD, HPF Gen 2 exhaust DEFIV kit, KW clubsport, Delrin solid subframe bushings, stoptech rotors, Rogue Tranny Mounts, 1M bumper, M3 CF hood, MORR VS8.2 rims 245/295

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