After mechanic replaced fuel pump gas gauge does not work. on 2001 Ford F-250 Super Duty

Took my truck to mechanic for routine maintenance and he replaced the fuel pump. After I got the truck back and filled the gas tank I noticed the fuel gauge wasn't reading correctly. It was reading but only showed 3/4 tank when I topped it off. I could also see the gauge move a bit while driving. Took it back to the mechanic and he said that the new fuel pump must be bad. He then replaced the new fuel pump 3 times pulled the gas tank twice and still cant fix it. Any ideas?

by in Chino Hills, CA on April 06, 2011
1 answer 4 comments
ANSWER by on April 06, 2011
was the fuel pump assembly a complete unit with the float assembly?? some of them you have to change over the sender unit. he may have bent the float removing or installing. or it could be a connection at the harness for the module assembly. if this has 2 fuel tanks, the connection at the switching valve needs to be checked. thanks for using repairpal Roy
COMMENT by on April 06, 2011
Thanks Roy, All that sounds logical, and the truck only has only one gas tank if that helps. Basically at this point I told the guy that since he cant fix it I'm taking it to the Ford dealer. He told me that if they fix it and can prove that it was something he screwed up, he'll pay for the bill. I just don't know a lot about cars and was curious if changing the fuel pump was related to the fuel gauge problem I'm having. Just looking to get this thing fixed without having to take this guy to small claims court.
COMMENT by on April 06, 2011
the short answer is yes, it is directly related. what brand pump did he use?? Roy
COMMENT by on April 06, 2011
Well the first two were aftermarket and when the problem persisted he finally switched to a Motorcraft pump. Then when he ordered the Motorcraft pump he initially told me that they had a different pump for each truck dependent on wheel base and wasn't sure he was getting the right pump. Later called me, said all was fixed, and I picked up the truck. A few days later I filled the tank and here we are.....
COMMENT by on April 06, 2011
well, he is correct about different pumps. you have to know the exact gallon capacity of the tank. the wheel base is importaqnt but the gallons is more. may be that simple. Roy