intermittent starter or ignition issue?, where to look next? Options

[DRPHIL914]

So this issue has happened 3x now in the past few months, and now today after driving 300 miles up to Brevard, NC on the way , stopped to get gas, going to start it, no crank. all other electronics work, fuel pump priming just no starter engagement. it’s happened cold too, i can get it to start by push start.. so about an hour ago i pulled the steering wheel and replaced the plastic switch still no starter , i also checked the yellow wires under passenger seat (seat buzzer by-pass) , i don’t think that’s the issue.

I bought and installed a new Bosch starter about 6 months ago and installed it on this newer motor a few months back, so now i am wondering if it’s a bad solenoid? wond not crank . the last time it happened was a months ago, push start got me home from the store, and when i got home and pulled into the garage after turning it off it started right back up and has for the next 10 times —- until tonight.

what are the other possibilities? does the power go from the ignition switch to the relay board and then to the starter? i have done a few searches , but looking for someone that’s maybe had this issue or understands the whole schematic better . i don’t have a multimeter with me but i can get one tomorrow at O’Reilly’s and i might see if they can get a starter., i’m just guessing and grasping at straws ..

- oh, for those that don’t know it’s a ‘75 2056 d-jet.

Phil

[technicalninja]

If you have a degraded signal coming to the solenoid engagement spade a common Bosch relay has been my go-to for years.

Adding a Ford solenoid is the same fix but that Ford solenoid needs 3 amps to trigger.
A Bosch relay needs 0.3 amps to trigger and can supply 30-40 amps if needed.

Modern cars all have a starter relay and the OEMs are no-longer running solenoid power through the ignition switch.

Seeing power at the small line to the starter but that power is not enough to trip the starter, add direct power (bump switch, screw driver).
Starter works?
Add relay.
30 comes from large bat term at starter, 87 goes to start solenoid connection (small spade on starter). 85 is signal from ignition switch and 86 is your relay ground.

Works great and if you're smart on the 85 lead you add a second wire to and put that somewhere in the engine compartment to allow easy connection of a bump starter lead...

Ford solenoid is nothing more than a BIG relay that can supply 300+ amps and drive the entire starter. The Bosch fix cannot drive an entire starter, but it can easily drive a starter solenoid like our 914s have.

It's not a bad idea to also add an inline 15-amp fuse before the Bosch relay in the 30 leg to protect it from a grounded solenoid.