89 911 Starting Problem I need help..
 

I have an 89 Euro. My car has an sporadic starting problem. When ever I least expected the motor starter clicks only (like when your battery is dead) not cranking / turning the motor. This happens at times when the car is completely cold or hot.

I have replaced the starter, I have a new fully charge Optima battery, the positive leads terminals have been replaced, the negative leads have been re-tighten. No corrosion all leads are clean.

Is there a relay that is part of the system? Any suggestions. Tony

Does the fuel pump come on when you turn the key? If not could be the fuel pump relay or fuel pump. The relay is the second or third relay from the firewall on the fuse panel. Check the red power wire for burning/crystallizing. Get a new relay. Give it tap and it may get you out of a bind. Good luck

Check the ohms on the ref/speed sensors and CHTS as well.

Electrical portion of ignition switch.
 

964-613-012-00-M100 Part # for you. Had the very exact same problem.

same problem I had, same approach I did. at the end, it's simply a wire that was my trouble maker. Search for "yellow wire" on my name, rnln.

Getting the engine to crank isn't an engine management issue. You can rip out the DME, fuel pump, etc, and the starter will still spin the engine.

As jibmaster1 said, it could be the ignition switch, but it could be a bunch of other things. Need to test things so you aren't flinging money blindly at it.

First you will need a volt meter with some fairly long leads so you can read it while trying to crank it. You will also want some wire to use to jump connections so you can bypass things while testing.

When trouble shooting you need to start with what you need to crank the motor. You have a good start on this by checking the battery and the cable ends.
First do easy stuff.
- Check the voltage at the battery when at rest (12.5+).
- Check the voltage when trying to crank and make a note of the drop. If it doesn't drop at all you have a complete connection problem somewhere.
- Use a jumper lead to engage the solenoid. If it doesn't crank from the key but it does crank from the jumper then the issue is the switch or the wiring from the switch.
- Check the voltage at the battery cable connection to the solenoid. When cranking it should drop the same quantity as at the battery. If it is different you need to check the cable.
- Check the voltage at the solenoid's connection to the starter when cranking. If you don't get voltage or you get low voltage then the solenoid is having trouble.
- If you have full voltage from the solenoid to the starter but it doesn't crank then you either have a bad starter or the ground strap from the trans to the body has issues.

That should chase it down for you.

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There was a post about adding a relay to the starter circuit (maybe in the 914 section) to help with mostly hot start issues. I really like the idea of taking the load out of that expensive ignition switch and putting it in a cheap disposable relay.

Would the pinion gear not meshing into the flywheel cause the solenoid not to energize the starter motor?

Good question Rick, I've often wondered the same thing. The PO's dilemma is similar to the same issue we've all had at one point or another, and the same one that I've had the darndest time tracking down. Whenever I've had the "click click" issue, I usually move the car backwards or forwards with the key off while in gear. Then, the "click" goes away and the car immediately starts, as if the pinion was somehow binding on the flywheel.

Curious.