Stumped, not starting

[kvin112]

Ok, I understand there has been a bunch of postings on this and I don't want to beat a dead horse or whatever that saying is. I have restored this car (1992 318 vert) about 85% complete. The OBC was tore up so I found one in the junk yard exactly the same to mine.  When I shut off the engine it still stays on so it drains my battery if I don't use the car frequently. So, I need to jump my battery if I don't use my car in 2 weeks. I guess my battery gave up. But its still holding a charge. My car just won't start. There's no clicking sound so I'm wondering if its the fuel pump or starter.  Either one has not been replaced. I have never replaced my alternator either. I have tested all fuses for everything.  A month before this happened my blower and radio stopped working. I really hope its not the ECU because that would be expensive. Any advise would be greatly appreciated!

[kvin112]

oh right...forgot to mention when i do turn the key the lights are very low. Someone suggested that this was the starter and to hook up jumper cables from the charged batter to the starter and try to jump it that way as there maybe rust inside of it.  Not sure if thats a good idea or not.

[DesktopDave]

Get the battery load tested.  Any auto shop will do that for free.  Or put a multimeter on it and make sure it's well above 12vdc.  A resting battery (with the car off) should be at least 12.8vdc.

If the battery is good and you want to test the starter, I'd put it in neutral & use the battery with some jumper cables.  Clamp the black wire from battery negative to a good engine ground, then clamp the red from battery positive to the starter main terminal.  Be careful not to hit anything else going in...it's pretty tight in there.  The starter solenoid should thump & the starter should spin the motor.  Take care as the motor may flex a surprising amount on worn M42 mounts.

The starter won't turn if the battery isn't giving enough amps.  If the battery is a little flat you'll hear the relays clattering.  If the battery is really flat the under-voltage relay will disable the whole starter system to protect electronic parts like the regulator and DME, so it'll seem like the starter is dead.

If you have a battery charger you can give it a good charge.  Mine goes to 10amps at 12volts, it'll charge up a flat battery in about an hour.

[fiftytakedowns]

there are usually a couple things that lead to no start.

NO fuel,
no spark,

both of which are controlled by the crank position sensor.