Fuse 21 melted, now car won't start

[guido_ar]

Hey guys, I need you to give me some rope here because i'm lost.

Yesterdeay I washed the car with my PW, as I have done many many times. When I started to dry the door jams, I immediately saw smoke coming out from right side B pillar. I rushed to open the hood and noticed #21 fuse was frying. Cutted off the battery as quick as I could, tried to remove the fuse (already melted) and when I connected the battery again (half an hour later or so), the car wouldn't start at all. It cranks but apparently I have no fuel or spark.

Things I have already done:
1- Partially removed the fuse box and the wire is fried (red/green). The rest of the wires seems to be ok, but they are all laced with a zip tie, which I didn't remove.

2- Removed and inspected fuel pump and unloader relays, both seem to be ok

3- Carried out the stomp test after connecting the battery and cranking it a couple of times, in both cases it gives me the "1444" code (everything ok).

I suspect the culprit is the door switch (water may have entered and mede the short circuit) but what really annoys me is what the #21 fuse has to do with either fuel or ignition. I've checked several wiring diagrams and none of them seem to relate any circuit protected by this fuse with the DME.

Has anybody experienced something even close to this? Of course radio, antenna and interior lights are out, but I really need to find out why the car won't start.

Any advice will be much appreciated. Thank you and excuse my english.

Cheers
Guido

PS: The car is a 08/1988 US Spec 325i

[Billwill]

You may have more than one problem here ie. something else is wrong other than a blown fuse 21.

If your vehicle has the battery in the trunk then the one black wire that goes up front to the battery junction block has a "fusable link" in it which may have blown at the same time as fuse 21 blew.

This lead splits into a few red wires going from the junction block and these supply power to the fuel relay, injection electronics and pin 14 in the diagnostic connector.

Put a voltmeter on the junction block to see if there is +12 volts on both terminals....one terminal is the one described above and the other one goes direct to the power distribution box, starter, alternator etc.

If this is not your problem:

Are you getting a spark?
Is the fuel pump running when the engine turns over?
Are the spark plugs wet?

[guido_ar]

Thanks a lot Bill!

Indeed, my battery is in the trunk. I've already connected a 12V lamp in the front junction box, and it works perfectly. I forgot to mention that all other electrical services are working (windows, central locking, lights).

Regarding your questions:
1- I do have spark
2- Have to sort that out. I should jump fuel pump relay to verify it works.
3- Sparks are dry (no fuel leaking).

Thanks a lot again!
Cheers
Guido

[Brianmoooore]

Water getting into the door switch would not cause your problems with fuse 21, or the frying wire, and the circuits supplied by this fuse have nothing to do with the running of the engine.
Definitely jump 30 to 87 on the fuel pump relay and confirm that it runs.

[guido_ar]

Thanks a lot Brian. I finally found the problem. Today I checked the fuses again and no. 11 (fuel pump) was blown as well. Replaced it, cranked the engine and it immediately blew again. Then I disconnected the fuel pump, replaced the fuse, checked resistance across the connector (0.2 ohm, short circuit) and after cranking the engine it blew again!

Started to remove the carpet on the right side, and found that one of the wires is completely melted (the one that runs to the trunk light). Of course, it melted the other wires along with it, including a ground that I'm pretty sure it is used by the fuel pump. So, it looks like I'll have to replace the entire loom.

Could anyone please confirm wether this loom is the same for all E30's?? If so, I could source it locally from a 318i that is being scraped.

Thanks a lot for all your answers!!

Cheers
Guido