M50B25NV Harness Install Questions

[Jafxod]

So once upon a time I was driving my swap car around and the temp gauge just went dead while I was driving, after this happened I got terrible gas mileage. Im talking like <5mpg. So I replaced the sensor and sender, nothing. My current was looking real bad and I had a feeling that was the issue so I swapped in a new one, but It seemed a tad different. I hooked it up and everything was a go except I wasnt getting fuel. Seems as if its not grounding (had this issue last time I pulled my motor and reinstalled to do the oil pan)

So heres my question, which are hots and which are grounds

Big red wire that goes that has one lead to the started and one that was labeled from PO as fuse box, guessing e34's used this and I dont need it.

This really confuses me, the big black wire that comes from connector at the battery tray, that goes to the starter right? Becuase the last mentioned cable I have going there too. And there is a wire that goes between the started and alternator thats hot to right?

Then there the cable that comes from the fuse box to the battery tray and splits off into 2 seperate connectors.

I think thats it, that you so so so so much to who ever takes the time to help me out, I havent driven my e30 in to long =[

The 2 wires that come out of the diagnostic connecter wire on passenger side

[MattM]

for the big leads, One wire goes from the B+ post to the Starter, one goes from the starter to the Alternator. In essence connecting them both to the battery.

And yes, both the E34 and E36 fuse boxes get power from the engine harness. This wire can be removed.

The rest of the smaller diameter wires that are in the battery tray area you need to peel back the black wrap and see the wire colors. All REDS attach to the B+ post, and browns attach to ground

[Jafxod]

Thank you very much. Time to check it all out.

[Jafxod]

Ok so can the entire wire that was supposed to hit the fuse box be eliminated or just the splice out to the fuse box, becuase right now I have to 2 wires going to my starter from the battery

[MattM]

on mine the wire was spliced into the main big lead running from the B+ post to the starter. and i just had to cut it at the splice, then shrink wrap that area..

If you can remove an entire 'harness' and still have the power where you need it then i dont see why not.

[Jafxod]

So I have everything connected up and still no fuel, which pins do I have to jump on the fuel relay to test if its bad

[MattM]

double check all the red leads are connected, i missed one the first time around that powered the DME.

[MattM]

if you jump pin 30 and 87 on the relay the fuel pump should go