E30 Won't Run Without Having Power To Positive Terminal Under Hood

[E30GuyMitch]

I recently had to drop the fuel tank and fix a fuel leak coming from where the filler hose enters the top of the tank on the passenger side. Reconnected the wires to the top of the fuel tank for the fuel pump and fixed a couple more leaks on the hoses by the fuel filter. Went to start it and it was dead so I used a jumper pack to connect to the upper nut on the positive leads under the hood and it started and ran fine. Took the jumper pack off and it died right away. So I replaced the battery thinking that was the problem, but now it cranks fine but doesn’t seem to be getting fuel and won’t start. The jumper pack will not start it unless it is hooked up to the top nut of the battery terminal. So maybe that bypasses a ground that I’m missing on the fuel tank? All the wires seem back in place but the wiring on the fuel level sending unit on the drivers side of the tank seems to be a little loose. But I messed around and tried to get them to fit better but that didn’t seem to help the problem. The fuel pump and relay should be good since it runs fine with the jumper pack in that position. Let me know if anyone has some suggestions

[packratbimmer]

About a foot or so from the + batt. terminal in the trunk there is a fusible link. Have you looked at that? It is shrink wrapped so look for a bulge.

[E30GuyMitch]

Found the fuse by the battery terminal in the trunk but it doesn't look like its been messed with at all since I just cut off the OEM shrink wrap. The other photo is the wiring on the driver side of the tank, inherited the car from my uncle and as you can see it was a little halfassed when he threw it together.

[venerated]

I don't think you would be able to tell if the fusible link (which is what is under that second layer of heat shrink) is broken unless you look at it directly. It has a metal line going through it that would be broken.

[E30GuyMitch]

Well I cut it open more. Feel a little stupid now but it’s for sure broken. So it’s probably shorting out somewhere in the car? Or if I replace it will be okay? Thanks for these Sunday responses lol

[E30GuyMitch]

Another thing that confuses me is that it seems like more stuff shouldn’t work if that breaker is broken. Right? I have dash lights and wipers and headlights

[e30austin]

that wire is a fused 12v lead, going straight to the DME. it's only purpose is to protect the controller, in the event of someone reversing the polarities when jump starting the battery. you can bypass it (put that power wire straight to the battery lead in the engine bay) for testing purposes, but i wouldn't leave it like that permanently.