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.

A: Fuses are over current protection devices w...

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

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: Wondering about tire size

Hi there. Usually the rule of thumb on plus sizing is anytime you increase the tire width, you need to reduce the aspect ratio (or that middle number) by one size. So, in this case, if you increase your tire...

Q: Car won't start

Check to see if the Theft Light is on or blinking while you are trying to start the vehicle. Try another key to see if the problem continues. If it does, then have the vehicle checked for fuel pressure and...

Q: Interior dim lights out and won't come back on

Hello, thank you for writing in. The fuses that you need to check are located inside the cabin near the dashboard. These are the fuses pertaining to lights you are concerned with. Keep in mind the vehicle should always be...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.