Issues with gas smell at the rear of the car but no leaks.

For the last couple months I've noticed a slight smell of gas at the rear of the car but I've yet to see any leaks. The smell is stronger at the rear of the car so I don't think it's fumes coming from the cap. I did notice today that when I unscrewed the cap I didn't hear the sound of pressurized air coming out like I normally do which leads me to think it is escaping somewhere else. And my gas mileage has dropped from 18-19 to 15-16. Not sure if they are related but it could be. Any ideas?

A guess--sending unit lines on top of gas tanks. Probably isn't leaking enough to show spots as it probably evaporates on the top of the tank.

Tom

I agree with Tom Mike,just had the same thing happen to my Suburban

Hope all is well otherwise, Lorne

There are 3 lines out of the tank. In, Out, and vent. the first two are under pressure.

Kinda what I thought. Any idea what size hoses are on top? If I pull it apart tomorrow while my wife is at work I will have no way to get to the parts store. I really don't want to ride my Schwinn Fastback

I had that gas smell thing happen to two of my wagons. One was a split in half vent hose, and the other wagon was a fuel return line w/ a pinhole leak on the hose's quick-disconnect fitting where it goes onto the fuel pump. IIRC the feed line was 3/8" and the return line was 5/16"

You can not just replace the fuel lines. You need the proper connectors on the fuel lines to connect them to the metal lines.

Fred Kiehl wrote:

You can not just replace the fuel lines. You need the proper connectors on the fuel lines to connect them to the metal lines.

Yup, you'll need some quick disconnect fittings and lines with barbs. They sell short pieces of lines with barbs at the auto parts stores as "fuel line repair kit" then you'll need to pickup the correct quick disconnect fittings for whatever hose you're replacing. Then you have to heat the lines up with boiling water or something to get the connectors to fit into them. It's a lot of fun doing this outside when it's below freezing...

Lynol wrote:

Fred Kiehl wrote:

You can not just replace the fuel lines. You need the proper connectors on the fuel lines to connect them to the metal lines.

Yup, you'll need some quick disconnect fittings and lines with barbs. They sell short pieces of lines with barbs at the auto parts stores as "fuel line repair kit" then you'll need to pickup the correct quick disconnect fittings for whatever hose you're replacing. Then you have to heat the lines up with boiling water or something to get the connectors to fit into them. It's a lot of fun doing this outside when it's below freezing...

Oh yay. So it's not like the older cars with hoses that have clamps on each end? Think this would have any effect on mpg?

I had an issue with Grimace when I bought it. The top of the tank was cracked. It only leaked when you topped it off. Found it on the first fill up.

Luckily I just so happened to have a tank lying around, lol (pays to part a car).

GN1220 wrote:

Lynol wrote:

Fred Kiehl wrote:

You can not just replace the fuel lines. You need the proper connectors on the fuel lines to connect them to the metal lines.

Yup, you'll need some quick disconnect fittings and lines with barbs. They sell short pieces of lines with barbs at the auto parts stores as "fuel line repair kit" then you'll need to pickup the correct quick disconnect fittings for whatever hose you're replacing. Then you have to heat the lines up with boiling water or something to get the connectors to fit into them. It's a lot of fun doing this outside when it's below freezing...

Oh yay. So it's not like the older cars with hoses that have clamps on each end? Think this would have any effect on mpg?

No, no clamps. It depends on what's leaking. Hopefully you will get lucky like I did and it will just be a leaky hose or connector and not the metal tubing on the sending unit! Just go under there with a flashlight and a camera and take a look. I was out working on the '96 Rustmaster's exploded cooling hose just now, so I took some pics of the fuel hoses while I was out there. What had happened was my return line was bad, -had a pinhole rust through on the connector at the pump sending unit. So, since the return line doesn't have much pressure in it, and since it was 20° out when we did this, I used boiling water to connect the new fitting to the short hose inside the house, and then after multiple attempts trying to warm/soften the end of the hose on the car which had shrunken to a ridiculously thin diameter from age, I went out and bought a 5/16" hose barb to female threaded connector and then bought a smaller than 5/16" hose barb to male threaded connector and clamped it on the hose on the car with a hose clamp. Half-assed? Maybe, but it works well enough. This car is scrapyard bound soon anyway, so I had nothing to loose. Now if it were the feed line, I wouldn't be able to do this because of the pressure, and I would have had to wait for warmer weather/ a better idea / pay a real mechanic.
On the left is the vent hose, the middle is the return line I had to replace some of, and the right is the feed line.
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And here is a picture showing the connector I pieced together!
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Lionel,is that area easily accessed from underneath so replacement of all the lines is possible?
My OCC occasionally emits the same odors but only when my tank is full.
Thanks

If its the feed line that's leaking above the tank you can swap the line out with one from a junk yard car. The line disconnects at the fuel filter. The sending unit that came out of lynol's rustprice was a rust bucket and showed signs of seeping already.
I helped him with the leak and finally found it when I had him start the car while I was under there watching the lines (a mirror helps). It had a pinhole that was producing a fine mist of gas, fine enough where it wouldn't drip but you could smell it.

Flasheroo wrote:

Lionel,is that area easily accessed from underneath so replacement of all the lines is possible?
My OCC occasionally emits the same odors but only when my tank is full.
Thanks

Yes, all lines are easily (that is a relative term) accessible w/o dropping the tank (on the LT1 wagons anyway). If you're replacing all lines, you may want to drop or partially drop the tank as it might make it easier in the long run.

95BRMW wrote:

If its the feed line that's leaking above the tank you can swap the line out with one from a junk yard car. The line disconnects at the fuel filter. The sending unit that came out of lynol's rustprice was a rust bucket and showed signs of seeping already.
I helped him with the leak and finally found it when I had him start the car while I was under there watching the lines (a mirror helps). It had a pinhole that was producing a fine mist of gas, fine enough where it wouldn't drip but you could smell it.

I take it you mean the Rustmaster? I forget, did you replace the sending unit in this car when you changed the fuel pump when you first got the car?

Thank You!