Hi all,
Long time lurker on this forum, first time poster. We've been slowly fixing up a 1987 325is, using a lot of insight from previous posts on this forum, but this is the first time we've been a little stumped on a problem.
We recently reinstalled the gas tank and some of the wiring. After double checking everything, we went to start the car (we had to jump it since the battery had died in the time the car was down for the project). The engine cranked, but would not start. We measured voltage across the pins on the fuel pump, and there was nothing. So, we went into the engine bay to check out the fuse and relay.
The fuse was fine, but the relay didn't seem to be triggering when we tried to start the car. We jumped the relay pins and we could hear the fuel pump click on/off, so that's all fine. Now, here's where it gets a little confusing. The switched connection of the relay is getting >12 volts when we measure across it, and the signal to relay is about 11.6V (when attempting to start the car). A little low, but not unreasonably so. This does not trigger the relay, so we assumed it was a bad relay. We tried a different relay in the socket, but that didn't work either. So we tried to put 12V to the switch in the relay (where signal would go to) - they both clicked on. We looked through the electrical diagrams and multiple electrical troubleshooting trees for this area, none of which addressed this particular situation.
So, we have good relays, a good fuel pump, and apparently a good connection to the relay that has the correct voltage across the switch AND signal (a tad low) going to the relay. Could the slightly low signal be causing this? Any ideas on what other items could cause this issue?
Thanks for your help!
Long time lurker on this forum, first time poster. We've been slowly fixing up a 1987 325is, using a lot of insight from previous posts on this forum, but this is the first time we've been a little stumped on a problem.
We recently reinstalled the gas tank and some of the wiring. After double checking everything, we went to start the car (we had to jump it since the battery had died in the time the car was down for the project). The engine cranked, but would not start. We measured voltage across the pins on the fuel pump, and there was nothing. So, we went into the engine bay to check out the fuse and relay.
The fuse was fine, but the relay didn't seem to be triggering when we tried to start the car. We jumped the relay pins and we could hear the fuel pump click on/off, so that's all fine. Now, here's where it gets a little confusing. The switched connection of the relay is getting >12 volts when we measure across it, and the signal to relay is about 11.6V (when attempting to start the car). A little low, but not unreasonably so. This does not trigger the relay, so we assumed it was a bad relay. We tried a different relay in the socket, but that didn't work either. So we tried to put 12V to the switch in the relay (where signal would go to) - they both clicked on. We looked through the electrical diagrams and multiple electrical troubleshooting trees for this area, none of which addressed this particular situation.
So, we have good relays, a good fuel pump, and apparently a good connection to the relay that has the correct voltage across the switch AND signal (a tad low) going to the relay. Could the slightly low signal be causing this? Any ideas on what other items could cause this issue?
Thanks for your help!
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