Fuel fumes inside

[kmhowell]

I need some advice. My Avanti is RQB2423 1976, and I've owned it since 2001. Restoration completed in 2008 and we've put 12K on it since. Recently noticed strong fuel smells inside the car when parked with the windows up. Checked tank and all three lines, no leaks found. Replaced the rubber portion of the tank vent line, fuel return line and main fuel line. Relaced rubber on the filler neck and the replaced the gas cap too. Still have the fuel smell. Has anyone else experienced this? If so did you find the source? Thanks KR Howell 8588293375.

[Gunslinger]

If everything is physically OK...no leaks or seepage from any seals, rust holes in the tank seams, etc., try putting sealer around the panel between the back seat and the tank itself. It was originally sealed, though few seem bother to reseal it after needing to remove the panel for any reason.

Also...check under the hood for any seepages or leaks or a defective carburetor. The odor could be coming in from there through gaps in any seals or grommets in the bulkhead or ventilation system from deteriorating weather seals, packing, etc.

I don't know if Avanti's of that time period had charcoal filters for emissions purposes...if so, it might be saturated and require replacing. Just a suggestion...as I said, I don't know if they had such filters installed.

[kmhowell]

If everything is physically OK...no leaks or seepage from any seals, rust holes in the tank seams, etc., try putting sealer around the panel between the back seat and the tank itself. It was originally sealed, though few seem bother to reseal it after needing to remove the panel for any reason.

Also...check under the hood for any seepages or leaks or a defective carburetor. The odor could be coming in from there through gaps in any seals or grommets in the bulkhead or ventilation system from deteriorating weather seals, packing, etc.

I don't know if Avanti's of that time period had charcoal filters for emissions purposes...if so, it might be saturated and require replacing. Just a suggestion...as I said, I don't know if they had such filters installed.

Thanks for the info Gunslinger. I did reseal the panel with putty when I reinstalled it. The Carb is a new Holly 770.

I haven't thought about the filter - I do have the black charcoal filter container under the hood which is attached to the tank by the vent line. It looks like original equipment so I don't think it would hurt anything to change it out if I can find a new one. Any ideas who might carry them?

The manual pump was pumping 9 lbs of pressure so I put a regulator on it and have it set at 4lbs. Runs OK at 4, but I blew out a power valve at 9. What about using an electric fuel pump. Have you ever done that on an Avanti? Could I eliminate the fuel return line if I did? And where would be the ideal spot to mount an electric pump.

All three lines from the fuel tank that run down the passenger side of the frame and they look dry - although there is undercoating on them obstucting a good complete view. Those line looks as if they are metal, I'm tempted to pull them and replace them with new ones.

Hope I'm not wearing my welcomne out but it's nice to have someone to bounce these ideas off. If you got any suggestions send them over and I'll give them a try. Would like to get the wife back in the car but she ain't going to do it if it smells like the inside of a gas tank. She prefers perfume to high octane :-)

[Gunslinger]

I'm guessing you could probably find a charcoal filter through a NAPA, Pep Boys or similar auto supplier. You may have to match it up side-by-side or from a catalog picture. Vapor canisters (charcoal filters) are also available from vendors that supply the Corvette market with reproduction parts, but they mount back by the fuel tank. Whether they can be adapted I don't know. Maybe they're available for Camaro's, Chevelle's and other GM cars the same way.

You can add an electric fuel pump to your car...I have one on mine. I have EFI installed and it requires an electric fuel pump. Mine is mounted under the gas tank between the rear frame crossmember rails. The only drawback is the noise...it does make a high pitched whine that's normal for such pumps. If you do install an electric pump, you need to use fuel line made for that use...mechanical pumps operate by negative pressure (vacuum...sucking the fuel from the tank to the engine). An electric pump operates by positive pressure...pushing the fuel from the tank forward. You need hoses made for the pressure.

Why do you have a fuel pump that puts out 9 psi? That's way too high for a street car. A stock pump shouldn't be doing that...is that a high performance pump installed? That might be a big part of the problem...pumping too much fuel...regulator or not. That extra pressure has to dissipate somehow...maybe your vapor canister is saturated due to that.

[kmhowell]

I'm guessing you could probably find a charcoal filter through a NAPA, Pep Boys or similar auto supplier. You may have to match it up side-by-side or from a catalog picture. Vapor canisters (charcoal filters) are also available from vendors that supply the Corvette market with reproduction parts, but they mount back by the fuel tank. Whether they can be adapted I don't know. Maybe they're available for Camaro's, Chevelle's and other GM cars the same way.

You can add an electric fuel pump to your car...I have one on mine. I have EFI installed and it requires an electric fuel pump. Mine is mounted under the gas tank between the rear frame crossmember rails. The only drawback is the noise...it does make a high pitched whine that's normal for such pumps. If you do install an electric pump, you need to use fuel line made for that use...mechanical pumps operate by negative pressure (vacuum...sucking the fuel from the tank to the engine). An electric pump operates by positive pressure...pushing the fuel from the tank forward. You need hoses made for the pressure.

Why do you have a fuel pump that puts out 9 psi? That's way too high for a street car. A stock pump shouldn't be doing that...is that a high performance pump installed? That might be a big part of the problem...pumping too much fuel...regulator or not. That extra pressure has to dissipate somehow...maybe your vapor canister is saturated due to that.

Good tips, Thanks, I'll check NAPA for a cannister plus I'm going to go with the electric pump and change out the fuel lines too, eliminating that return line. The manual pump I'm using now came with the ZZ4 350 crate engine I installed. I wasn't aware of the pressure until the power valve problems. You've been a big help. Hope I can get that smell out of there before the warm months set in.

[Skip Lackie]

I can confirm that a clogged or malfunctioning carbon cannister can cause quite a stink inside the cabin. Before you spend the money on a new cannister, check to make sure that the hoses to/from it don't have any leaks. The cannisters themselves can be expensive, but should be available, maybe even from GM. Since it's emissions equipment, parts have to be available for a long time. Make sure you match it with one designed for your engine displacement. It's possible that your new engine, carb, and fuel pump exceeded the capacity of your old cannister, which might have been designed for a 2-bbl carb,

[wdaly]

I can confirm that a clogged or malfunctioning carbon cannister can cause quite a stink inside the cabin. Before you spend the money on a new cannister, check to make sure that the hoses to/from it don't have any leaks. The cannisters themselves can be expensive, but should be available, maybe even from GM. Since it's emissions equipment, parts have to be available for a long time. Make sure you match it with one designed for your engine displacement. It's possible that your new engine, carb, and fuel pump exceeded the capacity of your old cannister, which might have been designed for a 2-bbl carb,

There is also a 'filter' media on the canister. Maybe try and clean IT first and see if that helps. Think it is located on the top area - made to filter to the atmosphere (I think).

[wdaly]

There is also a 'filter' media on the canister. Maybe try and clean IT first and see if that helps. Think it is located on the top area - made to filter to the atmosphere (I think).

OK, the filter (disc) is located on the BOTTOM.

[kmhowell]

I can confirm that a clogged or malfunctioning carbon cannister can cause quite a stink inside the cabin. Before you spend the money on a new cannister, check to make sure that the hoses to/from it don't have any leaks. The cannisters themselves can be expensive, but should be available, maybe even from GM. Since it's emissions equipment, parts have to be available for a long time. Make sure you match it with one designed for your engine displacement. It's possible that your new engine, carb, and fuel pump exceeded the capacity of your old cannister, which might have been designed for a 2-bbl carb,