Fuel Pump Fuses

new 9/17/02

Tim,

I think this thread might be a good addition to the website.

If you have time.

I see people almost everyday that oversize fuses to 'get by' and this situation illustrates the hazards of doing so. I saw a car burn in my parking lot because a kid insisted on replacing a fuse in his DSM with a larger size, because he was tired of screwing with it. I told him not to....

Regards,

David

----- Original Message -----

Sent: Wednesday, September 11, 2002 9:42 AM

Subject: Re: HELP! Fuel pump replacement help needed

Fuses are often sized to protect the wiring, rather than the device on the end. Weight in cars is very carefully maintained. The wires are probably sized no larger than the fuse intended for them. Even if the pump could handle it, the wiring might melt and burn. Or it might just melt, and melt all the wires near it.

30 amps is 360 watts. So the circuit was dissipating up to (and possibly more than) 360 watts. In your case, it was at least a little more than 20 amps, since it took a little while to blow (unless it was an intermittent short). So probably about the energy of a 250 watt light bulb, and likely little of that was going to the fuel pump. In the case of chaffing wires near the fuel pump, it was all concentrated at that spot near the fuel tank.

I have no particular knowledge of this particular circuit, nor Ford's fuse sizing practices.

I know that slightly over sizing fuses is a common diagnostic trick, but I would not oversize fuses in a car, unless it was worth the risk of the car burning.

Best Regards,
Doug

----- Original Message -----

I was driving to work this morning, car quit. Turns over fine. I checked the fuel pressure valve, very little fuel comes out. hmmm, must be fuel pump???? I checked the fuses, fuel pump fuse blown! Replace it, go two miles, quits again! Replace it again, get to Auto Zone, buy more fuses, put a 30 amp in place of the 20 amp, head back home, get 5 miles, it stops again. I check this fuse, it is hot to the touch but not blown, yet the car stopped anyway, so.... I am thinking it is definitely the fuel pump getting hot and stopping, or blowing a fuse. Auto Zone wants $269 for the fuel pump and will have to order it! Has anyone replaced a fuel pump, what is involved, how much was the pump, etc. ANY help appreciated! Thanks,

James Jensen, ES, 97,000 miles.

Thanks, James Jensen '97 ES 95k

Somewhere we have the TSB on bad fuel pump wiring.  If your fuel pump wiring has a short, using an over-size fuse will not solve the problem, it just creates a fire hazard. 

Thanks, to David, Doug and James

Buford