I posted some time back that my 89 740 B230F LH 2.4 system was giving poor mileage, running rich, and occassionally not starting due to severe flooding. A secondary, but no less important problem, was that my fuel pumps ran continuously when the ignition key was on.

I decided to replace the AMM and ECU with "known good" units that I purchased over ebay. The original ECU is a pink label 561 and I got a white label 951. Put the new ECU in there with great anticipation that it would solve all of my problems. HAH! Turned the key on and waited for the pumps to stop running. They did not stop but continued to run. Discouraged, I turned the key off and waited for the pumps to stop. They did not stop! The only way to stop the pumps is to pull the relay or to disconnect the battery. Replacing the relay or reconnecting the battery gives the original "off" condition...pumps not running. But turning the key on starts the whole process over again. I replaced the fuel pump relay with a new one and have exactly the same condition.

What the heck is going on? Could this condition be caused by the fuel pump(s) drawing too much current? Did a previous owner totally muck up the wiring somewhere somehow?