help with freakish non start problem

[1990C4S]

If it still wont start try marking up the jpg file with what you measured.

[Cdnone1]

Ok I had some time this morning so Here is what I was able to measure.
At the battery 12.66
At terminal 30 12.66
At the yellow wire inside front 12.66
At the 14 pin connector
Terminal 1 11.76
The car will start with the direct switch I rigged from the battery to the solenoid but runs like crap after about 1 minute
Obviously I have a problem somewhere from where the yellow wire leaves the split in the trunk to the 14 pin connector in the back.
Can you take the 14 pin connector apart?
I'm looking for suggestions, and thanks

[twin plugged targa]

Hang in there!
I have an 87 930 with very similar - if not the same- symptoms as you.
My car will start fine, run smooth and then other times will not start at all.
Search under my user name and 'stranded' plus 'non start continued'
I have also just changed for new my;
Starter switch,
battery
CD box and rotor (permatune)
spark plugs,
plug cables
Starter motor (new refurbished)
And yet the car still had issues!
My car is also in the garage on axle stands as I type
I will be interested in what you find and will try and PM you if I find a solution to my problem.
I am going to try a few more electrical tests as advised by 'Joe Bob' and may then try and remove the new (refurbished) starter motor and have it serviced.
I believe there are NO new starter motors out there - just refurbished!
apparently the solenoids get sticky, grease dries up etc.
Never rule out weak areas completely as this can send you down the wrong path completely!
My car ran fine for a couple of weeks then - back to where I started - or not started
- These problems can make you 'lose the faith' and fall out of love with your 911.
This happened with my 1st one which I sold 10yrs ago (but now wish I had kept!)
Hang in there and read some old threads for new ideas (what I am doing now!)
Good luck
Ben

[Cdnone1]

So I was checking the 12 pin connector to the ECU rather than the 14 pin connector.

I am getting 11.76 at terminal 1 at the 14 pin connector.
I will get under the car and check for voltage at the starter tomorrow
Give me strength!

[1990C4S]

I still say flakey starter solenoid.

[schumicat]

I would look for any crimp connectors on any wires affecting the starting circuit. I had an intermittent start issue on another car and wasted time and money (replaced starter, etc.) before figuring out it was a 10 cent crimp that was loose.

[RWebb]

did you check all the flywheel ring teeth?

each and every one of them?

[johnsjmc]

I suspect the ground connection at the battery or the cable itself where it goes to the floor under the battery . Not the strap at the trans end. I chased a similar intermitent no start on a 1980 for about a year. Might have been a loose bolt on the starter connection coming out of the solenoid and into the starter also. I tightened that and replaced my battery ground cable (at the battery) and the positive cable end at the same time but one of these steps fixed it.

[twin plugged targa]

Problem is, you can clean the ground strap at the chassis at the battery and near the transmission, but you cannot clean the gound strap at the transmission without removing the transmission can you?

[Cdnone1]

No you can. I took mine off cleaned the case and installed a new on in my driveway with the car on jack stands and the trans in

[pete3799]

The ground on the trans. can be clean in place.
When i bought my car it suffered from occasional no starts (acted like the battery was dead- just a click from the solenoid) Cleaning the grounds solved the problem.

[boyt911sc]

Originally Posted by Cdnone1

Ok I had some time this morning so Here is what I was able to measure.
At the battery 12.66
At terminal 30 12.66
At the yellow wire inside front 12.66
At the 14 pin connector
Terminal 1 11.76
The car will start with the direct switch I rigged from the battery to the solenoid but runs like crap after about 1 minute
Obviously I have a problem somewhere from where the yellow wire leaves the split in the trunk to the 14 pin connector in the back.
Can you take the 14 pin connector apart?
I'm looking for suggestions, and thanks

Steve,

The yellow wire @14-1 (connector) is for the solenoid/starter during crank phase. It has nothing to do with the engine's performance like idle speed. If you could start the engine by rigging a direct wire from battery to solenoid and will not start without the direct wire from battery, you just identified the problem!!!!!

The question you have to answer is why does it start with the rigged wiring set-up and not with the original wiring? If I were in your shoes, I would do a more definitive investigation by testing the starter/solenoid on the bench. Not until you could eliminate that the solenoid/starter is causing this problem, you'll be going in circles chasing the culprit. If for some reason, the starter/solenoid is not the culprit, you have succeeded eliminating a critical variable. And focus the investigation towards other alleged culprit/s.

You could open and clean-up the contact pins for the 14-pin connector specially the two (2) yellow wires at #1.

Tony

[RatBox]

I have not read all this , but if it will start sometimes and not others. But will start with a jump from an addition voltage source (charger/jumper).

Had similar problem with a 3.2 carrera years ago. Turned out to be a faulty / corroded connection INSIDE of a battery Lead connector (fastener to Battery terminal). It looked fine for the outside. But inside the hole where the cable went into the Clamp itself . The connection was bad.

[Cdnone1]

There is a ground fault somewhere in the wiring harness between or at the 14 pin connector in the engine bay and the battery.
I ran a fused wire with a switch on it directly from the battery to the starter solenoid. When pressing the momentary switch the car starts.
I pigtailed the yellow wire from terminal one of the 14 pin connector and the direct wire I ran together at the starter solenoid, pushed the momentary switch and the fuse I installed on the direct line blew.
Therefore the current is traveling down the direct line up into the yellow wire and going to ground somewhere causing the fuse in the direct line to blow.
I unplugged the harness at the 14 pin connector installed a new fuse, turned the ignition key pushed the momentary switch and the car started right up.
This must mean that there is a problem/ short to ground somewhere between or at the 14 pin connector in the engine bay and the battery.
Correct?!
Thoughts?!
Anyone had this?! Suggestion on finding the ground short?
Thanks heck of a way to spend a Sunday

Steve

[1990C4S]

If I understand what you said then your yellow wire is grounded somehow/somewhere?

[Cdnone1]

Yes , but it appears to be a larger problem than just the yellow wire for the starter solenoid.
If I start the car with the direct line I installed it runs fine for about 30sec then starts running really rough then dies.
So there is a larger electrical problem with the car.
I have cleaned all the grounds with the exception of the one behind the fuel filter, which I will clean tomorrow but I am inclined to think that it is larger than just that bad ground (if it is). I think something must be grounding the system where it is not suppose to be.
I've run out of idea's

Steve

[RWebb]

disconnect wires & see if they still show a path to gnd.

[Cdnone1]

Disconnect which wire and how do I see if they have a path to ground?

[1990C4S]

Pull the yellow off the starter and measure the resistance between the yellow wire and ground.

[Cdnone1]

Thanks for all the help guys
I measured the resistance at the 14 pin connector
From the female end going out here's what I found out with my ohmm meter
Female side
#1,2,3,4,5,6,7,8,11,12,13,14 all 0
terminal 9 1.6
terminal 10 6.4

From the male side
1-0
2-86
3-124
4-4
5-1
6,7-0
8-1.3
9-16.9
10-0
11-6.6
12,13,14-0
It was jumping around on the make side of the terminal so I'm pretty sure there is a problem there