Google returns some similiar conditions on this problem. When tank is low, the gauge will wander, up to full, then to half etc etc. When I do put fuel in it pops to the right value, but as soon as I start to drive it starts again. Would this probably require a complete fuel sender unit replcament or a repair?

 

This started happening to my 01 Seville after about 14 gallons were used. If you are open to used parts, the 01 to 05 Seville, Deville, Park Avenue, and Lesabre all use the same sending unit.

I couldn't open the fuel tank lock nut with the tools I have so I just ordered the Kent Moore SPX J-39765 lock nut wrench to the tune of $152.89 with shipping and tax. (I fixed a sending unit on a Dodge 2500 in the past an hope to be able to fix the one in the Cadillac.)

 

Most likely fuel level sensor(it is serviced separately)is cause. The is an access plate in trunk to get to fuel pump module assembly, so tank DOES NOT have to be removed to correct.

 

Replace complete unit is over $525+labor, fuel level sensor is like $225+labor, I really need a decent Wrench to do this kinda simple work. When I was younger I would do these kinds of things myself, I have resorted to paying for services now. Go figure!

 

Don't need any special tools, a brass drift and a hammer work well. Just tap the collar around it opposite side several times it unlocks the collar and pump comes right out.
I just replaced mine on a 2001 Seville.....

 

How much did you pay?

 

Once I remove the access plate, remove the fuel pump(does battery need to be dissconnected?) How much difficulty is it to replace the fuel level sensor?

 

I tried using the hammer and drift method on the fuel nut to my 01 Seville but it didn't budge so I bought the special tool. It took the special tool and a strong pull on a breaker bar to pop it open. It took the same amount of effort to close it. It must have a tighter fit than some others.

To open it up you first have to remove two electrical connections. The second connector is for a pressure sensor. There are also two fuel lines that must be removed. They are removed without any tools by squeezing and pulling the plastic retainer clip with your hands.

The fuel pump assembly comes out easy, after lifting it hold it above the tank until the fuel drains out before removing it. Have a rag handy because there is a little more fuel that comes out when you tip the unit to get the float out of the hole.

After the assembly is removed, the sending unit easily unsnaps from the fuel pump housing. The flat spring conductors on mine were worn thru at the contact point. I rebent them and reinstalled it until I find a replacement. It is working, but is probably reading a couple of gallons off.

Mine went bad after nine years and 105,000 miles.

 

I paid 276.00.....plus my time

 

$276 must include the pump. I found a new sender, AC Delco part number SK1030 & GM part number 88963639, for $125.88 including S&H (w/ discount code OEHQ2010) at oehq.com. Fleet Supply has them for $119.81 including S&H.