E30 Zone

Hi, early this year I took on a 1990 318is as a bit of a project. It runs ok but very rich and in my diagnoses to this problem I noticed the middle relay of 3 (blue) under the scuttle is missing. When I fit one it clicks like mad and makes no difference to the engine speed/sound on idle.
Is anyone able to explain how the engine is running without the fuel pump relay fitted ?

Thanks,
Nick

Two possible explanations for this. Either there has been some serious bodging of the wiring, with a feed to the fuel pump wired directly from the ignition switch, or you are mistaking the lambda sensor relay for the fuel pump relay.
If the wiring has been bodged, then I'd expect the pump to run when the ignition is switched on, and the fuel pump relay should be the only one of the four pin relays with a green/purple wire going to pin 87. The relay holders are easily unclipped from the bulkhead to check the wiring.

Thanks Brian, I suspect some bodge wiring then (spent some of its life with the previous owner as a rally car) I did check to see if the empty socket had a green/violet wire to it as per the e30wiki. I will double check this evening though.

My understanding is that the relay is used as a safety feature to ensure the pump is pressurising only when the engine is running, also to enable the fuel pump to start from a lower amperage ?

With the ignition on would I expect roughly a 10sec prime time of the fuel pump before it shuts off ?

Thanks again,
Nick.