Yes, I searched the archives a bit...nothing found about this scenario.

'84 Duke automatic is the patient. OK, so I just filled up the gas tank, and I overfilled it. The receipt says 9.798 gallons, and the gas gauge was not quite on "E" (though we all know that means little, given the inaccuracy of these gauges).

Normally when I have overfilled a gas tank on other cars in the past, the excess fuel comes back up through the filler neck. But no fuel came up through the filler neck at all. Rather, it started pouring onto the pavement directly underneath the car from the tank itself. Is this normal? Is there an overflow relief valve on the tank itself? Do Ihave a hole in my gas tank, on the top of it perhaps?

I should also note that I have only been getting about 20 mpg, and it's an '84 4-cyl auto.

Thanks everyone!!!!

Ditkaphile,

Both the fuel fill piping and the fuel overflow piping are connected to the tank by a short section of rubber hose. If you do not have a hole in your gas tank as you discribed then perhaps the overflow hose section is either loose, come off or missing.

Another option could be that the overflow piping is also compromised in some fashion thus allowing the fuel to excape.

Hope this helps.

Most likely it came out through the carbon canister. This is one of the problems with the 84 although I suppose it can happen on other year models too. Just seems to always happen on '84s.

I have an 86 duke and it always over flows out the neck...er ....at least when I fill it with too much fuel. You know what I'm saying. Does it overflow the whole time you are filling (that would tell you if the neck is compromised or not, well it would at least give you a better idea)?

I don't know about Dukes , but that would put the leak within close proximity of the catalytic converter on a 2.8L. You'd better find that leak before driving that car again; that would be difficult to get to with a fire extinguisher, and it would be doubtfully effective anyway. I'm guessing it's in one of the rubber hoses that connect the tank to the filler pipe.

Thanks for the input so far everyone.

I don't think I have a "leak" necessarily, because I am not seeing any drips or anything on a regular basis. This only happens when I fill up, and I have a tendency to top it off too many times. I have heard that overfilling the Fiero can cause fuel to backup into the charcoal cannister. However I don't think it was coming from there...if I take a whiff of the vent on the decklid, I don't smell a strong gas odor. The side of the car, definitely a strong gas odor. And when I overfilled it, I heard the fuel dripping onto the pavement before I even had the nozzle hung up yet (but it was right at the end of the fill, right as I overfilled it). I looked underneath the car, and could see it dripping down from the fuel tank. And it wasn't all streaming down at one spot, it was dripping down in a fashion similar to a glass of water (imagine setting a glass under the faucet and turning the water on. When it overflows, it pours down the sides of the glass all over, not just in one spot).

The last time I filled up, it didn't overflow like this but there was a strong gas odor, much like there is now (immediately after the fill....the smell goes away after some fuel is used).

If the fuel pump has been taken out and/or replaced lately, you may have to pull it out again and make sure the ring and seal on the top of the tank are sealing correctly. This would explain the ability to fill the tank with as much as you say and the fuel spilling out from around the top of the tank. I had a Chevrolet truck do the same thing on me. I had the fuel pump replaced and the place that fixed it didn't get the seal quite right. I was able to get a lot more fuel into the tank than normal but whenever I filled it up, there was gas leaking out of the tank and onto the ground. I dealt with it until the brand new pump quit after about a year. Then I had the dealership do it and they got it right.

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Whade' "The Duck Formerly Known As Wade" Duck
'87 GT Auto
'88 Ferrario
'84 Indy

Duck, I heard a "DING DING DING" in my head after reading that. I don't know of the pump having been recently replaced, but your diagnosis fits the symptoms (hope you guys don't mind the occasional medical jargon...makes dealing with an ailing Fiero more fun for me, and it "Humanizes" the car.)

Perhaps if I just dont overfill it I can get away with it for awhile...but given that it's an '84, it will be a good idea to replace a lot of the tank-related parts soon anyway

Keep the ideas coming folks, I am a sponge for Fiero knowledge

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Ninety percent of the population thinks you'd have to be crazy to own a Fiero. I'm in the other ten percent!

It's obviously not coming out of the charcole canister if it's dripping from the tank area.
I just sold a tank, & when I removed the overflow hose I found the tube loose. You may have the same problem.
BTW I had the tube soldered at a cost of $40, spent $6 for tape, $4 for gas, & $23 for shipping. Spent 1 1/2 hours getting cardboard, making the box, & taking it to ship. Sold it for $71.60 at a loss of $1.40 for my trouble. At least the guy has a good gas tank now; better than stock 'cause the tube is soldered in very well. Just glad all sales don't go like that.
~ Paul
aka "Tha Driver"

Check the return flow tube as stated above. My 87 only leaked when I would fill it full (after it would click off and then I would try and pump more in) or I would park on an incline after filling it up. Once I burned off a half a gallon, it would stop leaking. Perma weld has fixed the leak until I get around to dropping the tank (Been 3 years now).

Chris

I had that happen to me once on my 88. I'm not sure what it was coming out from. I took the tank out later to replace the fuel pump and the o-ring and everything looked fine. The hoses were in good shape too.

quote Originally posted by Ditkaphile: Rather, it started pouring onto the pavement directly underneath the car from the tank itself. Is this normal? Thanks everyone!!!!

The bunghole is leaking on the top of the tank. There is a rubber seal on the top of the tank so either the seal is poo poo or the lines have loosened where they go through the cap.

When I moded my 88 tank I had to re-seal all the lines as they were all lose.

quote Originally posted by Ditkaphile: I should also note that I have only been getting about 20 mpg, and it's an '84 4-cyl auto.

Its the 3 speed auto that kills your fuel efficiency. I have a 85 4-cyl auto and I see about 22mpg, and I know of many others with autos that are getting around the same mpg.

New RWD drive Mopars had a big issue with this. I always fill to the brim when I get a fillup. After the first 10,000 miles or so, it started just shutting off occasionally when I filled up until I ran out a few gallons of gas. Seems that in the recyling system theres a check valve at the tank in the lines that runs up to the engine bay and back to the tank. What happens if you overfilled it, it kept the seal on that valve submerged in gas which led to rapid deterioration. This resulted in fuel running up into the intake system and flooding it out. The quick fix was a notice to never fill up past the pumps auto shut off. I think theyve either redesigned the system or changed the seal in newer models. I dont know how much of that crosses over into other makes that might use the same type emmissions system. Now I never fill past the auto shut off in any cars.