Gas tank issue...capacity has halved

[Fiatlanta]

Finally got the old girl back on the road last week and have been driving around a bit. She had sat for several months as I diagnosed a few electrical issues. The plan was to run out all the old gas and get fresh gas in it. Gauge was showing 1/2, so figured I'd get 90 or so miles.

Long story short, it died and was out of gas. Strange because it was still showing about half a tank on the dash. I walked to a station and got enough to get me home. Happened again today...had filled it up, but only took 4.5 gallons...then got to half a tank and seemingly ran out of gas again.

I've never had an issue with the gauge before, fwiw. Did letting it sit cause something to gum up? Is there a liner that got vacuum sucked to a smaller size? I'm not sure where to start, really. Any thoughts?

Thanks.

[18Fiatsandcounting]

Any thoughts?

Yes. I'd try a few things:

1. Stick a yardstick or the like down the filler hole to verify that you indeed have gas. The yardstick ought to reach down the filler tube almost to the level of the bottom of the tank, so as long as you see several inches of wet gas on the yardstick, you have gas. Full would be about 10 inches (a guess on my part).

2. Try loosening the gas cap just a bit and drive around and see if you still have the same problem. If vacuum is building up in the tank (preventing the pump from supplying the engine), this will remove the vacuum. Carry some spare gas with you so you don't get stuck.

3. You could just have a lot of crap floating around in your tank, and when the gas drops to a certain level, it starts plugging up the pickup line. If you haven't taken the tank out and rinsed it out, now may be the time. Or, you could remove the pickup lines assembly from the top, and peer down into the tank with a good flashlight. Look for leaves, ping pong balls, etc.

-Bryan

[spider2081]

I would remove the fuel sender from the tank and look inside with a flash light.
A pin hole in the pick up tube or a bad piece of rubber hose could let the pump suck air instead of fuel.

[Fiatlanta]

Any thoughts?

Yes. I'd try a few things:

1. Stick a yardstick or the like down the filler hole to verify that you indeed have gas. The yardstick ought to reach down the filler tube almost to the level of the bottom of the tank, so as long as you see several inches of wet gas on the yardstick, you have gas. Full would be about 10 inches (a guess on my part).

Good idea, thanks. I thought of trying to stick something in there like that, but was kinda worried about doing it.

2. Try loosening the gas cap just a bit and drive around and see if you still have the same problem. If vacuum is building up in the tank (preventing the pump from supplying the engine), this will remove the vacuum. Carry some spare gas with you so you don't get stuck.

I do have a small hole in the gas cap, as I had previously removed all the emissions stuff and plugged the line back into the tank that was for venting. After the first time it happened, the pump wouldn't draw fuel until I took off the cap...then it sucked up the fuel and the car started immediately. I think I'm going to make the hole a little bigger, just to be safe.

And yeah...until I get this sorted out, I have a can in the trunk lol

3. You could just have a lot of crap floating around in your tank, and when the gas drops to a certain level, it starts plugging up the pickup line. If you haven't taken the tank out and rinsed it out, now may be the time. Or, you could remove the pickup lines assembly from the top, and peer down into the tank with a good flashlight. Look for leaves, ping pong balls, etc.

-Bryan

I was hoping to avoid having to do that, but if I have to, I will. As I said, it did sit for a while...plenty of time for the gas to gum up and start clogging stuff up.

Thanks for the input!

[Fiatlanta]

I would remove the fuel sender from the tank and look inside with a flash light.
A pin hole in the pick up tube or a bad piece of rubber hose could let the pump suck air instead of fuel.

Yeah, that's something I'm concerned about...modern gas in old lines...it sat for a while, unfortunately...bad lines are definitely a possibility.

Thanks

[18Fiatsandcounting]

I think Spider2081's comment is excellent, as you could indeed have a pinhole leak between the pickup line and the fuel pump. As the gas level drops, the pump has to work just a bit harder to pull the fuel up and out of the tank, and a pinhole leak might make it stop working when the tank gets lower than half full.

If the fuel lines from the tank sending unit to the metal lines that lead up to the front of the car have never been replaced, it's a good idea to replace them regardless of whether this is causing your issue. And possibly all the rubber fuel lines coming out of the tank. Helps to reduce the smell of gas in the trunk as well.

-Bryan