E30 S50 swap - replaced FPR now fuel pump wont prime/run

[wakdog]

So I had a bad fuel pressure regulator on my s50 swap (car was running sweet until the FPR started leaking fuel into the vac line...

Ran the car and pulled fuse 11 to kill the pump to get the engine to use the fuel in the lines and drop the pressure (immediately replaced it and disconnected battery). Disconnected the feed and return lines and the vac to FPR, got the fuel rail out and put in a new FPR.

Put it all back together and connected fuel lines back up but now when I turn ignition to accessory I get no fuel pump prime and no fuel when i crank.

Checked all fuses and none blown and tried a known working fuel pump relay from my other car and no go. Bridging pin 30/87 on the fuel pump relay powers the pump and the FPR holds pressure...

Is there anything I can have knocked/disconnected that would cause this no fuel issue? Checked crank sensor and its still plugged in all good and is only 2 months old...

[wakdog]

Did some more testing, ran a known good DME and still no go. Plugged in a code scanner and it is throwing "26 DME VOLTAGE SUPPLY" as the only code (this can also relate to the DME relay apparently).

Have tried a working DME relay from another car and a FP relay from the same car and doesnt make any difference...

From what I can test with my multimeter, the only thing missing is the signal from pin 1 of the DME that turns the fuel pump relay on (there is continuity on the wire though)...

[e30pq]

Did some more testing, ran a known good DME and still no go. Plugged in a code scanner and it is throwing "26 DME VOLTAGE SUPPLY" as the only code (this can also relate to the DME relay apparently).

Have tried a working DME relay from another car and a FP relay from the same car and doesnt make any difference...

From what I can test with my multimeter, the only thing missing is the signal from pin 1 of the DME that turns the fuel pump relay on (there is continuity on the wire though)...

By any chance, did you swap the fuel lines to the fuel rail by accident?

I know it's not necessary to uninstall the fuel rail to install the FPR but if you pulled the rail...

[wakdog]

By any chance, did you swap the fuel lines to the fuel rail by accident?

I know it's not necessary to uninstall the fuel rail to install the FPR but if you pulled the rail...

Its a Vanos fuel rail so the feed/return lines are on opposite ends and pretty much impossible to mix up (i didnt move them at all so they are definitely correct.)


Did some more testing and for some reason now I have 12v power coming from pin 1 on the DME. This is meant to be the ground signal wire for the fuel pump relay, which obviously won't turn on if its getting 12v+...

Suppose the next step is to trace the wire from the FP relay all the way back to DME pin 1 and see if anything is broken and causing it to become live (I assume the ECU code i get for ECU voltage has something to do with the fact that 12v is meeting what is a switched ground by the DME and it doesnt know what is going on)