M20b25 swap into eta, no crank but push starts

Post Fri Jun 22, 2018 4:11 am

So, I have a 1986 325 eta that I recently swapped a 1989 m20b25 in to. For the first 4-5 starts it started up perfectly fine. For the first test drive the battery light was barely illuminated so I pulled it back in and turned it off. About 20 minutes later I went to start it again and the starter just clicked, it was late so I just left it. The next day I went to jump start it and nothing. No cranking and clicking of the starter. However it does start when push started but seems to idle really high, not sure the exact rpm as I haven't wired in the tach yet. What's weird though is while the car is not running the windows and blower motor all works fine, but when push started the windows and blower motor are inop until the key is turned all the way back to the off position and the motor turned off. I am completely clueless as to where to go from here. So far, I've checked and tightened all visible grounds, replaced cps, replaced rotor but not the distributor as it looked okay, replaced alternator, new battery and have switched the main relay out for a known good one. Any ideas on where to start looking next? I am at a complete loss

Post Fri Jun 22, 2018 10:26 am

Sounds as though you have the starter motor connections wrong.

Check them carefully.

Ben

Post Fri Jun 22, 2018 12:25 pm

Also check the engine-to-body earth strap is in good condition and making good contact at each end.

Post Fri Jun 22, 2018 12:54 pm

BenHar wrote:Sounds as though you have the starter motor connections wrong.

Check them carefully.

Ben

The starter connection is correct. Also when trying to start, with full headlights on they do not dim when the key is turned to start. Could this be a unloader or a ignition switch issue? Still not sure why when it's not running the blower and windows work but when push started they do not

Post Fri Jun 22, 2018 1:07 pm

Speedtouch wrote:Also check the engine-to-body earth strap is in good condition and making good contact at each end.

Earth strap seems to be okay, I cleaned the connections on each side, the strap itself is a bit old but isn't cracking or anything, only has one little spot where the insulation has rubbed through a bit. When I swapped this newer motor in I retained my eta's earth strap, does the m20b25 need a different/bigger earth strap?

Post Fri Jun 22, 2018 4:29 pm

So from what I've found online is that the relays and pin outs for the body side of my 86 harness seem to be a bit different from the 89 body harness/fuse box. Some of which include the unloader relay. I have a 89 fuse box/body harness that I'm going to throw in today and see if that solves my issues
https://www.r3vlimited.com/board/showth ... p?t=192882

Am I correct in thinking this will be the answer to my problems?[/img]