Odd scenario here...(2000 dodge neon, ATX 31TH)

The car will start and run if i replace the fuse, and sitting in park. I can rev the engine, I've shaken the wires in the engine bay, but it keeps running. When I put it in gear, the fuse blows. Looking at the schematic, there's really not much to the fuel system, but it does appear that fuse #21 feeds the ASD relay, fuel pump relay, data link connector, and pcm. it's a new pcm, so im doubtful it's failed (not to mention i'd be pissed), fuel pump relay must be fine if it can start and run, just as the ASD relay. What I'm thinking is it's a sub-system underneath the ASD relay, or the fuel pressure regulator (im ruling out the pump unless these pumps have been known to be really wacky, but im doubtful of that).

1. Can the fuel pressure regulator cause the fuse to blow somehow? I read somewhere it could, but would like verification, because honestly I don't see the correlation.

2. Could a failing injector, or ignition coil, cause a #21 fuse to blow?

Hoping someone has been through something similar. This has come out of nowhere. I recently got 2 CEL's, both at the same time. p0137, circuit low voltage on downstream O2 sensor, and p1193, circuit high condition on inlet air temp sensor. A third code popped up out of nowhere that seemed useless, p1899, park/neutrsal safety switch stuck in park or in gear.

 

the wires that plug into the computer, drive side behind front bumper are grounding out on each other. Had the same issue when some doucheboy mechanic yanked on the wiring. Your mtr mounts are also bad I think if you're getting that much movement under the hood

as for the repair pull the air box out of your way, clean the old wire sheathing well, use some good elec tape on each bare wire or liquid tape then bundle it up good and tight. Takes less then an hour in the shade

 

i will certainly give those wires a look. i believe it is in my fact my fuel pump though, because one symptom ive had that ive ignored is when i rev up during driving, practically at WOT, the engine will start bucking. to me, it seems a symptom of fuel starvation. various sources ive found online indicate that more often than not, electric fuel pumps gradually fail, rather than just kaput-smash-break with no signal.

so i will go ahead and replace the pump, but indeed check those wires you mentioned, tejas, appreciate the response!

 

so the problem still remains. to be more specific, the engine will run fine in park, i can rev and no problem. I put it in gear, and it will idle fine. as soon as i give it gas under load, that's when fuse #21 blows. I have removed the main wiring harness and gone through it, and there are no shorts (aside from that, it doesn't make much sense to be a short, given the circumstances in which the fuse blows).

any further insight would be great.

 

found it!

in the downstream O2 sensor harness pigtail, while I repaired the frayed wiring right where the wires meet at the plug, i finally cut away that (fiberglass?) heat shield wrap, and sure enough, there was a mess of melted, frayed wire, just like the CKP pigtail AND the VSS pigtail. moral of the story? never assume a section of wiring is good because you can peek in to see a part of it. i initially only cut a small part of that heat wrap and the wires seemed fine, so i assumed they were good to go. of course that was the source of the whole problem.