nize

so i have a new problem, it seems fuse 13 will sometimes randomly fail, which shuts off the fuel supply, which stops the car dead, in the middle of an intersection during rush hour (and other really bad times).

i can immediately replace the fuse and everything is fine and the car runs great for another day or two, and then the fuse blows again.

this is a 15amp fuse, so i've tried replacing it with a 20amp fuse just to test, and it still blows the 20amp fuse. i do NOT want to try replacing it with a 30amp fuse.

does anyone know why this fuse would randomly fail? there seems to be no rhyme nor reason to when it decides to fail. thanks.

nize

by the way, this is a 1993 audi90 quattro. sorry i did not mention that in the first post. and yes, i have already replaced the ignition switch with a new one because it seems everything electrical is connected to the ignition switch or something.

Prospeeder

so the fuel pump and somehow injectors are on that circuit. Basicly a hot wire touching ground will blow the fuse. So your going to have to trace wiring. Good thing to do is have the car running, and pull and tug on harnesses that wiring from that circuit would be going through and see if you can get the fuse to blow. Then you have isolated a location. If the fuel pump itself was going bad and drawing more amprage than the circuit can handle, that would blow the fuse but not really likley.

MiShift

I would test resistance in your wires and voltages. You probably have an exposed wire somewhere that's shorting. I like the idea of moving the harness a little and seeing if you can induce the short. That's most likely what I would do.

audiqv8

Fuse 13 suppy power to the fuel pump and also power to the fuel pump relay. To test the pump get an ammeter and verify that the amp draw by the pump is within spec. Remove the fuel pump relay and apply power along with the ammeter to verify that the relay is within spec. If both check out OK then you will have to hunt down a short between the fuse and either fuel pump or fuel relay. Since you replaced the ignition switch recently I would verify that there are no exposed wire which might cause a short. Why did you changed the ignition switch?

nize

sorry for the belated response. i changed the ignition switch because of another (maybe unrelated?) issue outlined in this thread;
https://www.audiworld.com/forums/sho....php?t=2823115

nize

i thought i'd post another follow-up.

i've fixed everything else on this car so far, but this fuse 13 issue still persists.

it's been tough to narrow down because it happens so randomly.

nize

another update:

i've replaced the fuel pump with a brand new factory VDO brand fuel pump. the issue still persists and fuse 13 still keeps blowing.

i've tried yanking all of the ignition and fuel injector related wires in the engine bay and could not get the fuse to blow, but it will still blow randomly, usually when i'm just starting to go from a stop in first gear.

i'm not sure if i can figure out what is causing this, so i've replaced the fuse with a self-resetting fuse. at least if this happens again, i can just turn the ignition off and the fuse will reset itself and i should be able to immediately restart the car and continue driving.

if anyone has any other ideas, please let me know!

CRAZY_RUSSIAN

this may be off the wall, but have you done the trunk wiring harness? i know it makes no seance what so ever, but it maybe worth doing, lets put it this way, you wont lose anything if you do it. and its a simple slice and splice job

nize

thanks for your input. can you clarify exactly what the trunk wiring harness involves? should i order the entire trunk wiring harness from the dealer and replace the whole thing? or should i just replace a section of it? if so, which section? thanks!