starter problem- still- any help or ideas?

[gchappel]

HELP!
I have had intermittent starter problems in my 85 carrera for over 2 years. Basically the car runs absolutely fine- great in fact- except about once every 2-3 months, out of the blue, I get in, turn the key- and no starter. Luckily the car can be push started in about 3 feet. By the time I get the car home, it starts fine. We have replaced the starter- twice. Replaced battery, checked ignition switch, checked charging circuit, etc. Problem is completely random, sometimes hot, sometimes cold, etc. I wired in a auxillary starting switch- works just like the relay kit- from the 12V main lead to the starter to the solenoid input. This morning I get in the car- turn key- no starter. This was the first time it had failed since I added the starter switch in October- so I pushed the starter switch, motor started right up and I thought I had solved my gremlin. I get in the car to come home from work- no starter. No problem think I, I'll just use the aux. starter switch. This time it doesn't work either. Push start the car, drive it home, and now it starts fine. The aux starter switch- I think- should have bypassed all the other wiring. This is the 3rd starter that has acted the same way, so I doubt if it is the starter. What am I left with????
Grounds seem to be ok- I was going to add an additional ground strap directly from the starter- would that even be worth trying? The only other thing I can think of is the main cable itself from the battery to the starter- do these ever go bad? I was thinking of carefully running a 2nd cable directly from the battery to the starter. Any other ideas- this intermittent problem has really kept me from enjoying this great car- I just can't trust it right now, and my mechanic doesn't know what else to do. Thanks for any insight.

[3.2 CAB]

When you added the aux. starter switch, did you completely by-pass the yellow ign circuit wire, or are you still using it. Mine did that on me for a while, I always had to park where I could let it roll to start if I needed to. I fixed the problem by completely running a new yellow start circuit wire to the starter. It seems that the factory yellow wire would show continuity, but the resistance was so great that it would not carry the load at all times to actuiate the start circuit. I did not add any other switches, still use the ign switch, just wired it in, in place of the factory yellow wire. Good luck on your problem.

[gchappel]

The aux starter switch bypasses the ignition switch, at least I think it does. The ignition can be off, and the switch will still turn the starter over. Except when it doesn't.

[yelcab1]

What means no start? no turning over, no noise, no nothing?
What means replace starters? Did you have it rebuilt or buy a new one?

Did you (can you) measure the battery voltage while the key is turned to crank?

[gchappel]

Starter does not turn over- fuel pump is running, etc., but no noise, click nada from the starter itself. We have replaced the starter twice with new ones, as well as a new battery which checks out ok even at crank.
I am going to run another ground strap from the starter and keep my fingers crossed. If that doesn't work I will run a new lead directly from the battery. Does that plan seem to make sense?
Thanks
gary

[Wil Ferch]

Whoa!
"Fuel pump is running " ...?
Gary, from previous posts I think I know your car...a 3.2 with Motronic, yes?
There should be an interlock in the Motronic circuit to prevent you from running the fuel pump unless the engine is spinning/running. May want to check that angle...may even be unrelated to your problem, but I see this as a safety issue.
---Wil Ferch

[Early_S_Man]

Gary,

It would seem that 'shotgunning' the problem isn't working!

I suggest hooking up multimeter test leads to the outputs from ignition switch and DME relay ... that might point you in the right direction to go from where you are ...

[gchappel]

I don't like to shotgun problems either, but the problem is so intermittent we can't get a handle on it. The car has been to a good porsche mechanic 4 times for this problem. I flatbedded it twice so that it might be in a nonoperating mode when frank got to look at it. One time in 4 trips it was dead when he turned the key. The first voltage reading he took was the hot lead to the starter- he "thought" he had a low voltage reading- he said he rechecked his connections, the voltage read normally- but then magically the car had cured itself and started normally again. At that point he checked everything from the battery, back through the ignition switch, back to the starter- $700 diganostic dollars later he couldn't find anything. 4 months later when it died again he did the same check- this time on his nickle. That is when we just started replacing things. I ran another ground strap from the starter today- the tranny ground lead looked a little corroded. If the usual timeframe continues it will be sometime in May that the car will not start again. If it would just stay broke......
Will, I misspoke- I meant to say the fuelpump relay clicks normally- not the pump running. Wish me luck.
Gary

[targa911man]

Check the DME relay. I have the same car, had the same symptoms. It was the relay.

[RoninLB]

hey Gary..
when it doesn't turn over.. can you jump the starter sol directly from down under with a screwdriver ?

[targa911man]

I just thought of something else. Somebody (Steve Wong?) posted that some of these intermittent starting problems can result from solder in the DME box breaking down.

[gchappel]

Ronin, that is essentially what the aux switch does- which worked once and didn't work a 2nd time all in the same day. Question on the dme relay- will that really keep the starter from turning over? I thought the dme problems prevented starting, but the starter still worked.
Thanks again
gary

[RoninLB]

Originally posted by gchappel
Ronin, that is essentially what the aux switch does- which worked once and didn't work a 2nd time all in the same day. Question on the dme relay-

I knew that.. thanks for explain.
I was just trying to bypass another possible failure point from this keyboard.. I hooked up a momentary start switch in my engine comp..
From big starter hot
to relay[with sw]
to start sol

I know zero about DME

[3.2 CAB]

When mine was doing that, I totally replaced the yellow wire with a new one, have not had that problem since. That was 4 years ago.

[gchappel]

OK, yellow wire goes from the starter to the ignition switch? 3.2 cab-any tricks on making the run? I'll give almost anything a try now. Again, I added some additional ground straps, and I will wait to see if it fails again. If it does I'll try the yellow wire run.
thanks again
gary

[Aurel]

Gary,

I have had the exact same problem on my 78SC. I had my starter rebuilt, and when I reinstalled it, the problem still was not solved. When I turned they, all electricals would die. Battery was fully recharged.
Only yesterday did I find the true source of the problem: I have a knob switch on the negative battery post that can be used to disconnect the battery from the circuit. Turns out this switch was worn out and created a huge ohmic drop. I unscrewed the knob, and added a washer on the stud to make a better contact. Problem solved, the car started right away. Check this knob if you have one, and try the washer trick. It is probalbly the cheapest and most effective repair you will ever do on your car...

Aurel

[89911]

I had a similar problem that cost me a new battery, rebuilt alternator, and plenty of labor cost before I found it. The next time the car does not start, have someone carfully jiggle the positive lead coming off the battery. My mechanic found this out by accident. What had happen is the multiple strands of copper in the cable had become corroded, begining from where the sheathing ended near the terminal connector and going back about 6 inches. When it would not start, all you would have to do is touch this part and instant turnover. The answer was to peel back the sheathing revealing a greenish corrosion that prevented the wound copper acting as one conductor and clean. I used sandpaper and then flux and proceeded to flow electrical solder into the cable, essentially making it one solid wire. I then rewrapped the sheathing, used some plastic ties, and then replaced. I guess the corrosion had made it difficult to pass a large current through, but still allowed lights and other lower current drawing items to work. This does sound similar to your problem and since doing this my problem has dissapeared.

[cstreit]

Have you thought about checking your ignition switch?

[RoninLB]

Originally posted by cstreit
Have you thought about checking your ignition switch?

I change my good ign sw at 100k to prevent those PIA el problems

[gchappel]

My understanding is the starter bypass switch bypasses the ignition switch- and that also failed. I'll look at the switch again if the other rewiring doesnt fix it- ahhhhhh
thanks
gary