Strange Intermittent No-Start Problem (RB25 S14)

[StuckeyOG]

I’ve got this weird no start problem on my RB25 Kouki, it’s been like this since I picked the car up. It’s really got me stumped at the moment.

The car was originally an automatic so there is no starter relay that could be sticking. What happens is it will intermittently not start. The starter will throw the gear out and you can hear it contact the flywheel. Once I get it to start it usually will start no problem after. Occasionally it will start clicking again lol.

I’ve tested the jumper harness for the clutch interlock relay on the side of the fuse box, and there is no resistance.

It’s getting full battery voltage off the backside of the jumper harness plug down the power wire to the spade terminal on the starter solenoid. But if I put power from the fuse box down to the same terminal with the key on, it cranks over everytime? I suspected the plug connector to be bad so I connected another one and it made no difference.

- I’ve replaced the battery for a Bosch one with higher CCA then the original.

- I’ve had the starter rebuilt and even went back to the shop and had them swap out the starter solenoid for a brand new Denso one they pulled off a box on the shelf in front of me.

- I’ve changed the ignition switch on the back or the ignition lock cylinder for a new Beck Arnley unit just in case; once again it made no difference.

This issue really has me stumped, as it’s showing good voltage all the way through and if there was significant resistance to prevent the car starting it really should show a voltage drop somewhere. Not to mention that if the starter was sticking then it shouldn’t be starting just by me putting the same voltage from the fuse box down to the starter solenoid; as it would still be stuck.

If anyone has had a similar starting gremlin in a 5 speed swapped S-chassis that they sorted out, or any ideas in general- advice is extremely welcomed at this point lol. Thanks in advance.