Questions and Answers

BMW 320i Fuel Pump Troubleshooting Q. I have a 1981 BMW 320i, 1.8 liter engine, 5 speed manual transmission. The engine turns over, the spark plugs spark, but the injectors do not squirt fuel. I tested the wiring harnesses for both fuel pumps, in tank and outer. There was no power to either. I tried to trace the wiring for a break, but could not find one.

The fuse was okay, but there was no power at the fuse. I replaced the fuel pump relay, or what I thought was the fuel pump relay, since it was not marked on the fuse box cover. I have tested the fuel pumps by applying a battery directly to the posts. They tested okay. The injectors are new. Also, when the engine was running, I could not maintain an idle below 1,100 rpm. Any suggestions?

Gary

A. If there is no power at the fuse, then the problem is between the fuse box and battery. Power to fuse #3 comes from the ignition switch to fuse #3 through the green wire. It splits off with one branch going to the power bus and the other branch going to fuse #3.

If the headlights work, that indicates the problem is after the split. Running a new wire from the green wire at the ignition switch and the terminal in back of the fuse box should fix the no power problem.

By the way, here is a map of the fuse box.