Skip the auto shop - Our mechanics make house calls

Q: What could cause fuse to keep blowing from fuel pump

asked by on

In April I replaced a fuel pump in my S10. When they replaced it , it blew a 20 amp fuse. They put in new fuse and it ran fine till this week. 5 months later. The fuel pump was bad and was replaced under warranty. It continues to blow fuse and they can't figure out what the problem is. Any suggestions?

My car has 160000 miles.
My car has an automatic transmission.

Fuses are over current protection devices which means that you either have a short to ground (possibly intermittent) somewhere in the circuit or enough added resistance in the circuit that the current drawn by the pump is enough to blow the fuse. You can use a volt ohmmeter to measure the current draw of the pump and see if it is within factory specified limits.

If you have a wiring problem, you can re-do (bypass) as much of the existing wiring as possible (i.e., re-wire the fuel pump circuit) because otherwise you will have to laboriously go over the entire circuit until you find the wiring fault.

You should also check to see whether the fuel pump is only device on the fused circuit. If not, check the other loads on the fuel pump circuit as those other loads could be causing the problem (the overload). To check that refer to wiring diagram in Factory Service Manual.

There is also the possibility of a physical (mechanical) restriction in the fuel pump tubing, filter and/or pick up causing the motor to overload and draw more current than intended. That’s why you should measure the actual current draw of the pump in normal operation to rule that out.

If you’re unable to perform these checks yourself, have a certified technician, like one from YourMechanic, come to you and diagnose the electrical problem firsthand for an accurate repair.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Automatic transmission grinds when put in reverse

Hi there. Typically a grinding noise upon shifting is caused by a gear misalignment or the gear not fully engaging due to the wrong linkage being used. This is common with tranny swaps like you've described. The first thing I'd...

Q: Air conditioner

You need to take it to a different mechanic to have a diagnosis. You either leaked out the refrigerant or the system was overcharged. Have the pressures checked. The sealer will not seal a leak in an evaporator or a...

Q: Car will not start because of electric problem

The theft deterrent system on your vehicle has a module that needs to see a key that belongs to the vehicle to turn on the ignition so your vehicle can start. While looking at the theft light on the dash...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...