Tried to start the e30 today. (electrical troubleshooting)

[M-technik-3]

Is the pump getting power? If not you need to check for the short to ground, the length of the wire.

[Jordan]

The pump works just fine, If i jump the red and green/purple wires at the relay it buzzes happily.

otherwise the pump isnt working.

aside from those 2 wires there are 2 smaller ones that goto the fuel pump relay, while the car is cranked neither of them have 12v. I believe one of them comes from the ecu, and without that 12v the relay wont switch the fuel pump on.

now why isnt the ecu sending my fuel pump relay the signal to turn on dammit.

[rs4pro3]

My E28 has this same problem the pump will run when bridged but won't run whar started. I'm not getting the trigger voltage either. On the E28 the trigger pulse comes from the OBC harness. Are you positive that the wires are connected correctly since removing the OBC?
Try making a three way spade connector to bridge the fuel pump relay, that will kick the pumps on and see if you can then start the car. Basicaly bridge 30, 87, 87a

[M-technik-3]

Do you have a fuel pump relay jumper in there? It hard wires the fuel pump on at all times? You might want to see if that is the issue. Do you have a spare FP relay?

One thaing at time, It's a slow process. Next do you have a spare ecu?

[Jordan]

So if the trigger comes from(through?) the OBC harness, then perhaps I should go jack one from the junkyard and install the harness? Or would I need a OBC as well?

I'm fairly sure if I jumped those terminals the car would start, it should... but thats not the point, i need to figure out where the problem is

[rs4pro3]

I'm pretty sure the E30 is the same way I can go out and check my 318i that I retrofited an 87 OBC into and let you know. The obc it self has nothing to do with it but the Relay box does. I'll go look at my car and let you know where the conections are to bypass the relay.

[Jordan]

and the relay box is??? Is it the large rectanglular black box with 2 green connectors going into it?

[rs4pro3]

YA that is the Relay box, I just looked at my 318i and if memory serves me correctly I belive the conection was with the Blue brown two plong plug and the Green/red green plug. It's been a long time Since I did the conversion But I remeber that there were two plugs pluged intogether, then the OBC harness just plugged inbetween them. I'm not positve But I remember on my Friends 86 325e he came over and was doing something under the dash and unpluged these wires and the Car wouldn't start.
On a side note have you verified that the spark plugs are sparking?
Let me know if you figure this out as my E28 has no spark and no fuel when cranked, both relays replaced all fuses good multiple ecu's and it's been over a year since it last ran. I'm starting to suscept the OBC relay box being bad on it or the ecu, I'll be rulling out the Ecu's tommorow as I've got someone with an eta coming over and were going to test my 3 eta ecu's on his car.

[Jordan]

I will go look for those plugs.

No, I don't know if the car is sparking, seems a moot point at this time. I'll cross that bridge when I get there.

[rs4pro3]

I could be wrong about the conectors, Here is Fred's right up on the OBC install http://www.strictlyeta.net/technical/obcretrofit.html It's been to long since I've worked on the 318i to remeber what all I've done and since then I've pulled out 4 complete e30 chassis wiring harnesses.

[Jordan]

would these be them then?

[rs4pro3]

Those would be them, is that picture current? as it looks like the OBC harness is plugged into it. Oh and on one of your previouse posts you said you have a Lone white single plug with a red and red white wire going into it, this plugs into the little green plug that Slides into the back of the Speedometer.

[Jordan]

Yeah, i JUST took that photo. That is how it is currently connected.

what is that red/red-white wire before, because i dont even have that giant green connector on the cluster right now (i have it somewhere)

[rs4pro3]

I'm not sure, my 318i and my 88 325is both don't have it connected but on one of the 2 85 chassis harnesses I have in the Attic it is connected. Where does that harness run? Maybe try disconecting it?

[Jordan]

The other end of the harness ends over by the ECU, it is the OBC harness I guess. It has a green connector (to the OBC) on the other end, as well as a few other random connectors.