Fuel gauge wrong after new fuel pump

[BenHud]

I haven't been able to find this issue discussed anywhere.... I recently got a 1997 tj 2.5L, which evidently came with the "14gal" fuel tank (see pic). The fuel pump was going out, so after some research I decided to do the "air vent tube shortening" trick to the inside of the tank to gain the full use of the 19 gal tank while I had the tank removed. So I ordered the consensus best pump for the 19 gal tank, the Delphi FG1353.

I dropped the tank, thoroughly cleaned it out, and noticed that the air tube was already flush with the top of the interior of the tank, so I assumed a prior owner had already done it. I installed the new pump, reassembled, and went to fill it up with gas. It only took about 14 gal, and the fuel gauge read 3/4 tank, so I knew there was a problem. I drove it until it said empty, and dropped the tank again. It still had at least 4 gal in it (after driving it on "E" for maybe 20 miles).

I pulled out the pump, left the electrical connector plugged in, and moved the float around. It wouldn't go to "F" on the gauge when lifted up to the top, so I assumed a faulty sender on the new pump. I returned the pump for a new Delphi FG1353. I tested the new one (just plugged in), and the gauge went to full at the top, so I reassembled and reinstalled.

Went to fill with gas, and same issue. It took about 14 gal, and then read 3/4 tank. What am I missing here?

Thank you for your thoughts!
Ben

 

[KennethS]

I drove it until it said empty, and dropped the tank again. It still had at least 4 gal in it (after driving it on "E" for maybe 20 miles).

FYI, mine with the 19 gallon tank has around 5 gallons left when the Empty light comes on.

Sorry, can't help with the other issue but thought the above might help answer one of your questions.

 

[OldBuzzard]

According to Fuel Tank Size you have to cut the filler neck down. And there's another link in there to much more information.

 

[TheBoogieman]

I've driven mine until the needle was 1/8" below the actual E. Take some chances in life. After filling the tank, I still had a half gallon in there.

 

[lBasket]

I've driven mine until the needle was 1/8" below the actual E. Take some chances in life. After filling the tank, I still had a half gallon in there.

My gas light comes on with 5-6 gallons left a whole 1/4 of the tank

 

[TheBoogieman]

My gas light comes on with 5-6 gallons left a whole 1/4 of the tank

Pull that bulb and take some risks like me.