1996 Cadillac STS Short in fuel pump circuit?

BMCATMCA

MEMBER
1996 CADILLAC STS

Electrical problem
1996 Cadillac STS V8 Front Wheel Drive Automatic 137K miles

Dealer has replaced the pump three times, then another dealer checked and repaired the main fuse block (also fuel pump relay) as well as finding and repairing a short in the main fuse block harness.
Ran fine for awhile, but has been blowing the fuel pump circuit fuse with increasing frequency -- now 5 or 6 times on a local errand trip. I have been buying 30a fuses by the dozen (the circuit is rated at 20a I think).
Questions:
1) What is wrong?
2) If I replace the fuse with a jump wire will I damage the fuel pump (or anything else)?
THANKS!

1 Reply

KHLOW2008

MECHANIC
41,815 POSTS

Hi BMCatMCA,

Thank you for the donation.

The fuel pump fuse is for the fuel pump relay and oil pressure switch. Something is shorting somwwhere and it could be a wire that has been rubbed bare or something that has pierced the wiring. Since fuel pump has been replaced 3 times, the likelyhood of it being the cause is slim.

For such problem it is not going to be easy to detect and you should start by pulling the fuse, disconnecting the fuel pump relay and oil pressure switch. Use an ohmmeter to test the resistance of the pink wire to ground for continuity. If continuity is found, there is a shor in the circuit.

NEVER use a fuse that is higher than designate. Installing a 30 A fuse for a 20 A can cause wirings to burn due to shortings as the higher capacity fuse would take a longer time to blow and if wires in the circuit are of low capacity, it can start a fire.

Using a jumper would work but be prepared to get a new car if it burns off, hopefully you can get out of the vehicle in time.