So, I had to replace the fuel pump awhile back. Dropped the tank and got it done.

Of course, then the gas gauge didn't work, so after being annoyed as hell over it for a year, I dropped the tank again and replaced the sending unit.

Gas gauge worked again, but was reading funny. As soon as it hit "E", I filled it up. Only took 12 gallons. Repeated it a few times, always the same result. 12 gallons.

I figured that was just the way the new sending unit read, and decided to drive a little deeper into the "E-zone". 30 miles later, It started shutting off under hard-ish braking, and after right turns.

I filled it up, packing it as full as it would go. 13.19 gallons.

I've had this car since 2003. I've run it all the way dry more than once; it's always held 15.25 gallons.

It's never had fuel starvation issues with 2 gallons in the tank.

I wonder what's going on?

 

I guess you didn't check height difference when installing new unit? Could it be shorter? Or did you change just the pump and not the entire unit?

 

They appeared the same, but the issue that really concerns me is the fuel starvation.

In the past, it wouldn't do that until the last half-gallon of fuel. Now, it's either doing it with 2 1/2 gallons of fuel in it, or my fuel tank is holding 2 less gallons of fuel. Both possibilities make me scratch my head.

 

What does the owner's manual list for gas tank capacity?

What does the vendor claim for capacity of the tank you bought?

If this were me, I'd either live with the reduced capacity, or grab the air compressor, regulate the pressure WAY DOWN, and inflate the gas tank. Stock-car racers did this years ago to add fuel capacity, then if they were to be checked for rules violations...smack the bulging tank back to proper shape.

 

I didn't buy a new tank. I gought a new fuel pump, and a new sending unit. No changes at all to the tank, except when it was out I cleaned all the crap out of it.

 

Ooops. I screwed the pooch on that one.

I'm still curious about the claimed capacity of the tank, including whether or not the tank was dented in the removal/installation process; and if so, whether inflating it with low-pressure air will pop the dent and restore capacity.

 

I'm sure I didn't dent it. I got up under it and looked, and can't see anything.

There's still the top, but again, I'm sure i would have noticed if I'd dented it; especially a dent that took away 2 gallons of capacity!

 

Both pump length and the length of the sock is what you have to watch.

 

So, I replaced the pump well over a year ago. Everything was fine, except the gas gauge didn't work.

I drove it without a gas gauge, calculating the fuel level through mileage. I ran it nearly dry several times during that period, and it took nearly 15.5 gallons to fill it completely up, so it's not the pump length, or the length of the sock.

I dropped the tank again and replaced the sending unit. Now it's running out of gas at 13 gallons.

 

Did you compare the old and new sending units? Is the new one a little shorter than the old one was perhaps?

 

They were identical.

Regardless, the sending unit couldn't account for it now running out of gas at 13.1 gallons, when it used to run out of gas at 15.5

 

Well it could change it if the end position of the pickup is above where it was originally, due to the angle it's at or the length of the sender. But since they were identical it shouldn't matter. I'm a bit clueless then as to what would make it change, other than maybe the angle of the tank being different when re-installed but as long as the straps are tightened down, that would be hard to get wrong.

 

Have you checked to see if there is still two gallons left in an "empty" tank? If there is, it's something with the pump/pickup, if not, it could be a tank issue. misalignment or something. Are you fueling at the same pump? Like on an angle that causes less fuel to get into the tank?