Our 1998 Crown Vic is blowing the 30 amp fuse in the engine compartment that connects to the fuel pump, oxygen sensors, and a couple of other items. Obviously this leads to an unplanned and undesirable coast to stop with a dead engine. As far as I can tell, I could drive it without a problem as long as I never had to make a long left turn (such as a looping highway entrance ramp). Making a left turn from one road to another will not do it. So, I am "assuming" that something is shifting to the right and pinching a short continuously long enough to blow it. I have an auto electric shop working on it for two days and they can't figure it out. They have taken the wiring diagram and traced the wiring to/from all the components in that fuse loop. I was just wondering if anyone else had ever experienced this so that I could get more ideas where to look.
Thank you,
Eric

 

I think one of the major problems in troubleshooting this problem is what it takes to blow the fuse in the first place.

If you say that a long left curve is what is doing it then I suggest that it is the amount of force in G's that is causing either the engine or wiring somewhere to move and cause the short. (You know that already), so the trick is simulating the force experienced during those long turns.

So what if you jacked up only the left hand side of the car far enough to put as close to the amount of strain that you would get while driving and put an Ohmeter in series with Ground and either side of the good fuse in a non running situation and as you jack the car up, monitor the Resistance until you see the short or low resistance reading occur. Once you establish the short and can keep it then you can start disconnecting different parts that use that 30 amp circuit until the short goes away, and step by step you can then trace it back to the cause.

Unless you are going around the curves at super high speed to the point that your neck is about to snap, you might be able to cause enough sideways force by leaning the vehicle to the right, by jacking up the left....Ok I think I am beating a dead horse on that one.

I hope this at least gives you something to think about.

Good Luck.

Edit: It would be preferrable if you can do the test in a switch on, but motor off mode. Run mode I believe is what we are looking for, you can just take a DC voltmeter and go between ground and the fuse and turn the key to run without starting it and if you have 12 Volts there.....Good to go, if not you may have to start the engine and see if you have the voltage. Chances are you will have 12 volts there in only the run position. If you cant find the problem with it only in the run mode, try the test again with the engine running as the added torque might help duplicate the failure.