fuel pump fuse keeps blowing 79 911

[usaporche]

hello porsche lovers, new at this, i looked all throught the 56 sections to see if i could find any body with this problem but no luck, dont say i didnt try, but hey at first my fuel pump was working, than it started kind of erratecally ( sorry for the mispell) than it totally went out, i was going to buy a new one, thats when i noticed that the fuse was out, i replaced the fuse but it still went out, now should the fuse go out if the fuel pump is bad? i dont want to fork out the price of a new pump if i dont need too, any ways thanks for any help! HAPPY FOURTH OF JULY!

[piscator]

The fuel pump is not difficult to get at or take out. I would start by inspecting the two wires going into the pump itself. Check for crud, corrosion, loose connections, or anything broken.

If the wires are clean and sound, check for voltage at the terminals on the pump. You may need to loosen the clamp holding the pump or even drop the pump to get at the terminals.

If the connections are sound and you have a clean 12v + at the terminals, the problem may be the pump itself. I would probably replace it.

That decision, however, might depend on how the car is running -- which you didn't mention. Is it constantly blowing fuses -- so that it won't run? Or running well and occasionally blowing the fuse?

If the engine does run consistently, you can test the pump more definitively by checking the CIS fuel pressure back in the engine compartment -- there are several good threads on that subject.

Good luck!

piscator

[ossiblue]

Follow piscator's advice and check the connections first, but from your description--erratic behavior of the pump--I'd lean towards a bad pump. Yes, a seized pump or one with bad bearings that impede free spinning of the pump can cause excessive amp draw which is probably what you are seeing. Remove the pump and have it tested, or simply replace it knowing it as a thirty years old and will fail sometime soon anyway.