1986 325e M50B25: Relays not powering on

[MaxBell]

Hey all, so my swap is about to start up and here's the issue.

The fuel pump relay won't turn the pump on.

Things checked so far:

1. I jumped the connection to turn the pump on in the relay plug and the fuel line belches fuel all over.
2. The relay has power.
3. The relay is good, I tested it and it works if I ground it.
4. Pin 13 (FP) is wired properly. (Here's my wiring diagram!)

And so ya. It's not turning on with the ignition.

The only thing that is not hooked up properly is the C103 (C104?) connector in the glovebox is not wired into the "instrument cluster" and "engine speed out" wires.

I don't see that being a problem as those are instrument cluster display things, I think?

Anyways, any help is appreciated.

PS:

How are the fuel lines routed to the charcoal canister, and can I eliminate that thing in my 1986 325e car. Maybe just use a catch can?

[328ijunkie]

Power at pin 86 of the relay? The ECU fires a ground to pin 85. 30 is alwas hot and 87 obv goes to pump.

[hwy84]

Key on "on" or cranking?

When you say, it's not turning on with the ignition, do you mean when the key is in the "on" position, or when you are cranking the car?

I beleive that the ECU needs to see the crank spinning before it fires up the fuel pump relay... Unlike the m20 where the fuel pump kicks on as soon as the key is switched to the "on" position.

Someone will correct me if I am wrong, but this was one of the steps I had to work through when I had no fuel on cranking.

[328ijunkie]

^That. The ECU needs a crank signal before it will fire the FP relay/injectors/etc

[MaxBell]

WHAT!? I spent all this time troubleshooting with the engine to just the ON position, and not start.

Will report back.

[328ijunkie]

Fail.

;) lol

[Mr.SWISS]

Make sure fuse 11 is good also man.

[ForcedFirebird]

When you say, it's not turning on with the ignition, do you mean when the key is in the "on" position, or when you are cranking the car?

I beleive that the ECU needs to see the crank spinning before it fires up the fuel pump relay... Unlike the m20 where the fuel pump kicks on as soon as the key is switched to the "on" position.

Someone will correct me if I am wrong, but this was one of the steps I had to work through when I had no fuel on cranking.

Neither the m20 nor the m50 ECU's fire with key on, both have to be cranking.

[MaxBell]

Make sure fuse 11 is good also man.

All my fuses have been checked and are ok at both sides.

Neither the m20 nor the m50 ECU's fire with key on, both have to be cranking.

Good to know for the future. Looks like I was over complicating this swap, should have just plugged it all in a fired it up.

[ForcedFirebird]

Make sure you grounded the proper wire on the strut tower. The m5x/s5x harness has two identical black wires in that area, many people ground both or the wrong one and may burn the signal to the FP relay. If you peel the sheathing back on those two wires, the brown cluster goes to ground and the red obviously goes to battery positive.

[Mr.SWISS]

All my fuses have been checked and are ok at both sides.



Good to know for the future. Looks like I was over complicating this swap, should have just plugged it all in a fired it up.

Well you can crank it with the line disco'd to see which is the feed and make sure it fires first time!

[MaxBell]

Make sure you grounded the proper wire on the strut tower. The m5x/s5x harness has two identical black wires in that area, many people ground both or the wrong one and may burn the signal to the FP relay. If you peel the sheathing back on those two wires, the brown cluster goes to ground and the red obviously goes to battery positive.

Good call. I checked those two wires and one had continuity with the FP relay.

One is closer to the diagnostic plug, so I grounded that to the strut tower.

[SwiftE30]

Make sure you grounded the proper wire on the strut tower. The m5x/s5x harness has two identical black wires in that area, many people ground both or the wrong one and may burn the signal to the FP relay. If you peel the sheathing back on those two wires, the brown cluster goes to ground and the red obviously goes to battery positive.

this is the exact problem i had. i had the power hooked to ground. But in my case my fuel pump wasnt turnign on because my harness wasn't getting any power.

Has anyone mentioned a bad CPS? If its bad, it could be sending an improper reading to the ECU. What CPS are you using?

[xwill112x]

Make sure you grounded the proper wire on the strut tower. The m5x/s5x harness has two identical black wires in that area, many people ground both or the wrong one and may burn the signal to the FP relay. If you peel the sheathing back on those two wires, the brown cluster goes to ground and the red obviously goes to battery positive.

Where would you suggest attaching the B+ wire then?

[ForcedFirebird]

Where would you suggest attaching the B+ wire then?

Not to ground. I have had several swaps come in the shop and they hook the B+ to the shock tower ground. B+ obviously goes to battery, the distribution block works or in the case of the last swap (cabrio) on the battery post.