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Thread: Fuel smell - Air Vents

  1. #1
    Member madstudios's Avatar
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    Fuel smell - Air Vents

    Hi everyone!
    Today I drove about 2 hours in a hot summer day. When I was driving back home, I started to smell gas, apparently coming from the air vents.
    There is no visible sign of fuel leak.
    Any thoughts?


    Fernando Silotto. Sao Paulo - Brazil
    Delorean Vin 3772

  2. #2
    Motors about after dark Michael's Avatar
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    Open up the fuel pump area, remove the boot and check for any leaks there. Start the engine and let it idle and check again. If you see nothing look under the car and make sure your accumulator lines are not leaking (again while idling). If you see no leaks then replace your fuel cap.

  3. #3
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    Could also be the seal on the fuel sender. If it isn't perfectly seated/sealed, it can come sloshing up around the edges when you're driving and then the air rushing by takes it from there into the cabin.

    A good test to see if this is happening is to gain access to the top of the fuel tank by removing everything from your trunk, including the carpet board and spare tire, and then remove the access cover that's under the spare tire. You can now see the top of the tank and fuel sender. Check to see if there is any obvious fuel wet spots first. If not, and there may not be if it has evaporated, leave everything out of the trunk just like you have it and go for a little drive around the block. While going about 10 mph or so, slam the brakes on hard and come to a complete stop (make sure your neighbour isn't driving right behind you first!). Now pull over safely and have a look at the top of the tank and fuel sender and see if it is wet. If it is, you know where your leak is. Credit to Dave S. (of course) for sharing that little trick with me a year or so ago.


    Sept. 81, auto, black interior

  4. #4
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    Was the tank full or near full at the time? Typically a fuel smell is going to be something to do with the fuel tank. A bad fuel cap, a deteriorated fuel boot and cover, a leak from the sending unit, a hose, something. A wet spot is a great visual indicator but you aren't always going to see one. A through visual inspection of the fuel tank is the first step. To do that you must remove the access panel under the spare tire.
    David Teitelbaum

  5. #5
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    After two hours in a hot summer day, you probably have plenty of gas vapors built up in the tank as the radiator fans will heat up your gas tank. Lots of places around the tank where those fumes could be pushing through. If this happens again pull your gas lock and see if fumes pressure out. If they do, see about insulating your tank from the radiator fans. Hervey's hot-air dam is a good reference.

    http://www.deloreanautoparts.com/del...-dam-place.jpg

    That said I'd still check for leaks around the fuel tank as recommended by everyone else ^

  6. #6
    Member madstudios's Avatar
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    Fuel smell - Air Vents

    Thank you everyone for so many tips, you guys are awesome!
    I'll check everything tomorrow.
    Today it was about 95 degrees here in Sao Paulo, I went to a car show in a small town 50 miles from here. Everything went well on the way there (no smell at all), but I parked the car in the sun about 3 hours, and on the way back I've noticed the smell inside the car. This was the hottest day ever that I've used the car in a highway. I usually drive in the city.


    Fernando Silotto. Sao Paulo - Brazil
    Delorean Vin 3772
    Last edited by madstudios; 02-12-2017 at 07:31 PM.

  7. #7
    '82 T3 FABombjoy's Avatar
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    Tank vapors should not build up, but should vent into the charcoal canister. You may want to check the vapor lines at rollover valve / fuel fill area. These are what mine looked like last year.

    Evap_Hoses.jpg

    That's the hose going from the rollover valve to the hard vapor line on the frame. There is also a short hose that connects the fuel filler neck to the rollover valve. IIRC early versions of this hose are known to go bad.

    You have to pull the inspection plate just below the fuel fill to inspect these.
    Luke S :: 10270 :: 82 Grey 5-Speed :: Single Watercooled T3 .60/.48 :: Borla Exhaust :: MSD Ignition :: MS3X Fully SFI Odd-fire EFI :: DevilsOwn Methanol Injection

  8. #8
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    Quote Originally Posted by FABombjoy View Post
    Tank vapors should not build up, but should vent into the charcoal canister. You may want to check the vapor lines at rollover valve / fuel fill area. These are what mine looked like last year.

    Evap_Hoses.jpg

    That's the hose going from the rollover valve to the hard vapor line on the frame. There is also a short hose that connects the fuel filler neck to the rollover valve. IIRC early versions of this hose are known to go bad.

    You have to pull the inspection plate just below the fuel fill to inspect these.
    While you are correct that you should not get any vapors, if there are any leaks in the tank area you will get fumes. Find and fix any leaks and if you still get fumes there *could* be a problem with the vapor system. On some cars I have found the hose coming off the bottom of the vapor canister all plugged up with insect stuff. You can see that hose coming out of the bottom of the left, rear pontoon. On my car I had a problem with the gas cap. It was not sealing well. The rubber gasket was swollen and the spring was not able to seat it properly. Took it apart, cleaned it all up and now it's fine.
    David Teitelbaum

  9. #9
    Senior Member Drive Stainless's Avatar
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    A failed rollover valve will also cause pressure to build in the tank until you have liquid gasoline & vapors escaping through the gas cap.

  10. #10
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    Quote Originally Posted by Drive Stainless View Post
    A failed rollover valve will also cause pressure to build in the tank until you have liquid gasoline & vapors escaping through the gas cap.

    Very true, and the smaller hose off the rollover valve tends to kink with age. The article below has a good rundown on fuel smell sources.
    http://support.delorean.com/kb/a42/fuel-smells.aspx

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