Getting closer - 100hp starting questions

[Steve Mahler]

Thanks for the help so far - spent hours reading old posts. Have 1979 chrysler 100 new to me. With fully charged battery and all wiring harness properly hooked up, I get inconsistent electric choke action, and no solenoid click when key turned.

If I jump from the red battery cable post to the little yellow (shift interrupt, right?) post near it I get a healthy solenoid click.

If I jump from the batter positive post to the red starter cable post on the solenoid, and ground to the black starter post, the starter engages and turns, but slowly - even with no plugs in. (Compression is even and good across).

So, I am thinking I have a faulty key switch (funny choke action, no solenoid trigger)?

Any other thoughts?

 

[Frank Acampora]

Re: Getting closer - 100hp starting questions

First, there is no ground post on the starter. The starter is grounded through the mounting on the block via the top plate and the two mounting screws that pass completely through the starter motor. Another small ground wire comes from the regulator/rectifier to the block and that is ground for the charging system.

Second: the yellow wire comes from the neutral interlock switch on the side and below the bottom carb. It is a start wire. If the engine is in neutral, the micro-switch allows voltage to pass from the ignition switch and energise the solenoid. If the engine is in gear the switch is open and the solenoid will not close, thus: no cranking. If you hear the solenoid clicking when energised it does not necessarily mean it is good Burned contacts can insulate and even though it is closing, no current will flow. Have someone work the key and check that you are getting 12 volts on the other side of the solenoid.

I am suspicious of the fact you mentioned that the starter turns slowly. If you jump from battery side of solenoid to the yellow terminal on the solenoid, and if the solenoid closes, the starter should turn rather briskly with plugs, very fast with no plugs. Slow turning indicates 1. bad ground to the block--remove starter and clean contact point. 2 . low battery charge. 3. poor connection-high resistance connection (s) at battery terminals or at the battery side of the solenoid. 4. sick starter motor.

By the way: if your solenoid has two small terminals, the second is a ground and should be connected to the engine pan. If it has only one terminal, it is grounded through the steel mounting plate.

Old engines--ignition switches do go bad. however, check all connections to the choke. you may have a broken green wire that makes intermittent contact. Replace the green choke wire from the engine terminal board to the choke and see if that helps.

You have already checked the switch by jumping from battery to yellow PROVIDED that the shift linkage is not out of adjustment. Frequently the shift linkage is not centered on the micro-switch white button when the control lever is in neutral. turning the ignition switch results in no start and you THINK the ignition switch is bad. Jiggle the control handle to position the link on the micro-switch and see if the solenoid now closes with the key.

Hope that gives you some help.

 

[Steve Mahler]

Re: Getting closer - 100hp starting questions

Thanks for the help - please stay with me - I am close on this one. Let me respond to your questions and comments to see if I am going in the right direction.

1) When jumping direct to the starter I was jumping pos batt to pos cable leading from solenoid to starter. Negative batt post to the small black post on the starter which goes to the regulator. I believe my jump cables are either cheap/poor, or my connections flawed because on all 3 of my outboards I turn the starter slowly. The other 2 outboards run and start fine.

2) I have the shift interrupt switch fully pressed by the shift arc, but I also tried jumping that with no change.

3) Now the big question - I bought my first multimeter, never used one before - i previously verified with a test light that I have 12V on both sides of the solenoid as well as up on the wiring harness block (various colors). Where should I test for voltage to narrow my search for the problem?

I will go out this afternoon and take apart the key switch to jump directly there, elminating that possibility.

 

[eurolarva]

Re: Getting closer - 100hp starting questions

There is some confusion I am seeing on your post. Your first post concerns your Choke Solenoid not the Starter solenoid. Is this correct? Choke solinoid is engaged by pushing the key in while starting. Start solinoid is engaged by turning key to start and the only criteria that must be met is that the shifter is in neutral so the neutral interlock engages.

Jumper cables to the starter a lot of times will fail do to a thing called contact resistance. The teeth on battery cables does not give you enough surface contact to the starter so the resistance goes up and not enough current can pass to start the motor or you will see not enough power to turn it fast enough.

With multimeter in DC volt mode read the voltage at the small terminal on the starter relay. If that voltage is lower then 9 volts that could be the problem. If your battery is good you may just need to sand clean and tighten all electrical connections to the starter, battery, solinoid barrier strip and the ignition switch.

 

[Steve Mahler]

Re: Getting closer - 100hp starting questions

Thanks for your responses, I have been asking multiple questions at once, sorry for confusion. Today I have confirmed the key switch was bad, but my questions dont end!

When touching the red (pos) and green (choke) key wires together, the choke solenoid works great, a couple separate times. on, off, on, off - it will hold closed. But on try number 3 - no go. Nothing.

When I touched the red wire with the starter wire, I got the starter solenoid to click once - then nothing after that. Subsequent tries got no click and a slight buzz/pop from the battery cables, like a short somewhere?

So I may be forced to take this one in to the shop, I am weakest on electrics.