Installed battery backwards E28 518i 5 series BMW (1986)


Hello, instead of connecting the positive terminal of the battery to the starter motor, I connected it to ground. At first I did not see any spark because the ground terminal was disconnected. But when i approached the ground wire to the battery negative terminal a spark appeared. After fixing my mistake, the fuel pump does not stop when the key is turned to “start” position and there is no crank.

What is the most common fault that it is expected to have from my mistake? Fried ECU? Fried starter? Bad ground connection? Thank you

Double check your connections and then make sure the battery is fully charged. Check the related fuses and relays. Sounds like the fuel pump relay is stuck on. I don’t think you harmed the starter. If you hurt anything it would be the battery.