Where is fuel pump relay located on BMW e30 1988 320i

[Joosep]

Hi, i need help at finding fuel pump relay. Fuel pump is not getting power, when all the wiers are plugged in. Tester shows that there is little power in fuel pump plugs, put it is only 2V, but it sould be 12V?
It must be relay problem then? If yes, then can anyone tell me where i can find that relay?

[thejlevie]

If this is like other E30's, the fuel pump relay should be the middle of the three mounted over the left fender (intake side of the engine).

[Joosep]

Hmm i think we found what we were looking, but still there is no power in fuel pump cable. There are 4 cables going into that outlet where relay can be plugged in. So we took tester, and looked that 3 of the cables have 12V power on it, but last one is empty. So relay should switch that last one, and give fuelpump power? And for conclusion its true that relay is bad??

[garretvs]

Look on the bottom of the removed relay. (4) terminals:

86 - power from engine harness (Main Relay -- right next to fuel pump relay) -"pulls" relay in; hot in run/start (no voltage at all with key off) Also, main relay could be NG; it supplies power to fuel pump relay pull-in side
85 - the ground for 86 above (connected to Motronic which supplies the ground)
30 - (should be)* battery power -- hot always
87 - (should be)* power to fuel pump thru the round connector C101, then to fuse 11; on the firewall

* the (should be) above is because sometimes 30 and 87 are swapped (87 battery power, 30 to pump).

If your car has an O2 sensor relay, it may share power from pin 87 of the fuel pump relay. That relay and/or the O2 sensor may be robbing power from your fuel pump. Remove the relay and see if the pump performance improves -- if so, O2 relay &/or wiring NG

Check the fuel pump power wire for continuity/resistance between fuse 11 and the pump as follows:

Remove fuse 11. Turn key on. Find which side of fuse 11 is hot from battery: use voltmeter between one of the fuse leg slots and ground; if you get 11-12 volts, you found the "upstream" side, and determined it has battery voltage with key on. You want to check the other slot of fuse 11 for continuity between it and the power lug on the pump (needs 2 people and a long wire ) -- the power lug has (2) wires on it. You should get continuity, and have very little resistance.

[Joosep]

Okay, fuelpump relay seems to be OK.
Where is that O2 sensor relay located? Same box with fuelpump relay?

[Joosep]

Okay i have found the problem. Fuelpump cable is totaly burned and need replacement So, anyone have some electrical chart, where i can see which "road" the cable goes.