Electrical starting issue

[ross_jsy]

Having issues, after being sat up for a couple of months I went to fire it up last night. The solenoid will clunk but the starter won't spin. Took the starter out to bench test and it was fine so reattached everything and same thing. So tested the green/black feed wire and I get 0v with ignition off, however it gets 12 volts with ignition in position 2 (and same when trying to crank). Thought it should only have 12v in position 3?

Anyway I shorted out the small terminal and it spins up?

So any ideas? Swapped round the DME relay and looked at the fuses, seem ok. What relay is it in the fuse box?

m50'd 325i btw

Cheers,

Ross

[Speedtouch]

Check the solenoid. I had one go on a Fiat twin cam and it was because of cracks in the casing, so the terminals weren't being fully contacted when the solenoid coil was energised.

[ross_jsy]

Hmm I just bench tested it again and it will both engage and spin the starter when voltage is applied to the solenoid (larger of the 2 terminals) with no power to the smaller terminal. I might be wrong, but shouldn't it require power to both?

[Speedtouch]

The larger terminals are the main power feed from the battery to the motor, the smaller terminal is the trigger input from the ignition switch, that energises the solenoid coil.

[Brianmoooore]

Black/yellow is the start signal, not green/black.
No relays in the fuse box have anything to do with the starting or running of the engine. Same applies to the fuses themselves, except for the fuel pump fuse, #11.

[votivequagmire]

From the symptoms I would be checking out the main thick lead on the solenoid from the battery. Make sure it has enough strands connected at the ring connector and give it a good rub down with some fine sandpaper to ensure a clean connection. I'd also consider doing the same to the solenoid connection and the washer. Then make sure the other end at the battery is in the same clean condition. There's an awful amount of current which needs to turn the engine and anything reducing that flow will cause similar issues.

May be an idea to check out the chassis to engine earth which is normally just below. Make sure it also has a good sound connection. If it's been sat for a bit then some oxidation and corrosion is to be expected.

[ross_jsy]

Bit of an odd one, suspect it was the starter playing up. Bench tested it again, all was fine so put it back together and it started up first time.

[votivequagmire]

Oh cool. Love it when a plan comes together