Fuel tank/pump question

[ryanprins13]

Hey, i have had my car 9 years and up until about 2 years ago i only ran it out of gas twice. But without running out i had put in 36.5-37 litres a couple of times when fuelling up. In the last 2 years i ran out of gas probably 5 or 6 times now, managing to coast or coast-speed up-coast to a gas station all of them but once. And when i fuelled up it took 32-34 litres, thats it. I will have to dig out my old fuel book at home, but since september of last year i have put 33.5-34 litres in it 3 times without running out yet the last time i ran out only 33.5 litres went in. I made it probably 4 miles from where it started sputtering that time, i made 10 miles once, but twice it sputtered, died, and wouldnt start again 5-10 seconds after the first sputter. I pulled my fuel pump out just now. Im quite surprised at how clean the tank is. Pump and screen look fine. Nothing i can see that would cause problems. Now i have gone off-roading a lot and the whole underside of my car includin the tank is very dented. Going to re-install the pump i had to push down on it a bit to start the screws, is that normal? There is what looks like a 1/2in pipe coming out of the reservoir the pump sits in and wraps around the reservoir. Is the end of it thats in the main compartment of the tank closer to the engine supposed to be right on the bottom of the tank? The bottom of My pipe is 1/4 in or so up from the bottom. I tried to push it down with a stick but no luck. I have the opportunity to pull a used tank tomorrow if the tank is the problem. Any ideas about what my issue is? Thanks.


Its not the gas pumps that are off. Ive tracked my fuel milage since i bought it. Lost 5mpg when i siezed the transmission the first time but its been even since then. Fuel gauge still reads the same, i will run out right when it hits the red line, i used to be able to do over 100km after that point.

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[FestYboy]

One: STOP running your tank low!!! It will cause premature pump failure.
Two: the dented tank is causing the drop in capacity, replace it if you can't keep it filled. Don't take it below 6L anymore. And you should not have to force the pump assembly into the tank to get the threads started, that will put pressure on the pickup and sock, and may cause performance issues.

[ryanprins13]

One: STOP running your tank low!!! It will cause premature pump failure.
Two: the dented tank is causing the drop in capacity, replace it if you can't keep it filled. Don't take it below 6L anymore. And you should not have to force the pump assembly into the tank to get the threads started, that will put pressure on the pickup and sock, and may cause performance issues.

I have lost 4-7L of capacity, the tank is not that dented. Its got a couple small dents, thats it. Might be displacing 1/2litre. If i thought the dents were displacing more than that i wouldnt be asking questions :p. I also dont really think thats it because It doesnt run out at the same amount every time. That is also the problem of why i run out, i usually put 32-33L in it now, sometimes 34. But sometimes i run out at 31L. If i keep it 6L above that that gives me a range of only like 450km. I drive over 100km a day, gas up twice a week already. If the tank is the problem i will replace it, i just want to actually know what the issue is first. Replacing parts without knowing why isnt really my thing. I would think that 1/2 in pipe should be right on the bottom of the tank, thats why im asking about it. The pump did not seem tight when i removed it, couldnt seem to get it to fit any way loose when re-installing. No marks on the bottom like it had been rubbing before. Theres actually a big chunk of rubber on the bottom of the pump thats pressing on the tank, its not affecting the sock, but i agree, its not right. When i take it back out ill check if its still tight. Didnt take much pressure to push it down, it just wouldn't sit down all the way on its own.
Thanks for the input.

[FestYboy]

Ok, I'd be inclined to suspect the tank is pushed, but in such a way as to not be obvious. Use a straight edge that spanns the length of the tank and see if there's a significant bow in the center. 4-7L of missing volume is quite a bit.