Electrical Problem / Insanity, Starter issue Options

[jsaum]

Before I go totally insane I'm hoping someone can help me through trouble shooting a problem with the ignition switch not actuating the starter. First a little information, I have a late model year 1972 1.7 with the fuel injection removed and a carburetor installed. After six months of working on the car I've finally gotten to the point where I have installed the motor with a new starter The car has been apart for 12 years sitting in the garage. First the starter failed to work when I tried to turn it over. Thinking the new starter was bad I took it off and had it tested this morning at the auto parts store it works fine. I also had the battery checked and it is good as well.

I put the starter back in and it worked four or five times so I thought it was fixed. I then hooked up the fuel line and went to try and start it and the starter wouldn't work again!#@%###. I can jump it across the positive battery cable to the solenoid and it works. I have 12 volts on the yellow wire to the started solenoid when it is disconnected and 8.5 volts when it is connected when the key is turned. I have checked the relay board at pin # 6 and I have 12 volts there when the key is turned with the connector off. I ran a jumper wire to the solenoid from pin# 6 on the relay board and the voltage goes down to 8.5 when the key is turned to start so I think I have eliminated that the yellow wire is bad from the relay board to the starter solenoid.

I can't tell from the schematic my manual if there are other things in the circuit I should check. I'm wondering if my ignition switch is bad.

Anyone have any ideas or insight? Any suggestions or directions would be gratefully appreciated.

Thanks,
Jsaum

[Tom]

Jsuam,
This is a common problem with these cars. Can seem to be complicated,but, step by step working through this will work to find the problem.
First, your yellow wire has 12 volts with key to start and yellow wire disconnected from starter. Good, this means your ignition switch is making contact. When you hook the yellow wire up to the starter, the voltage drops to 8.5. Some voltage drop is to be expected as you are trying to energize the solenoid, but yours seems to be too much.
There can be several causes for this and all are probably bad connections. Definately check the transmission ground strap. Then check out the connector on the yellow wire and replace it if it looks corroded at all. Remember, these connectors are subject to outside forces, and water/heat can really affect them over time.
These selonoids have two , yes two, circuit paths for the holding coil to keep the selonoid energized while the starter motor is turning over the motor. Is your starter a new bosch one? Not sure if the other non-bosch units have the second holding circuit, which places added strain on the ignition key circuit. The second holding circuit is made when the selonoid contacts at the rear of the selonoid are made internally.
If you would like some more indepth explanations, PM me your phone number and I'll give you a call.
Tom