964C2-91: Startgurus around the world ...HELP!

[Blacklook]

To all startgurus of this 964 forum, your help is needed!

PROBLEM: My 964 C2 1991 suddenly is not willing to start anymore.
What have I already done?
Well, I put in a new battery (VARTA SilverDynamic 77Ah) and a new DME relay...

What's the behaviour now:
Well... i start cranking the (cold) engine which -with a new battery- is childsplay. I crank for about 15-20secs nothing happens but the moment when I let the key go back into OFF position the engine starts to sputter a little and if I play with the gaspedal a bit then, it comes to life. It will run for about 60secs...and dies on me.

When I then try to restart it... it just doesn't work anymore. Although... if I play a bit with the pedal (like pumping gas in a carb) and stop cranking there is again this slight hesitation and the motor would like to come alive...for 1 sec, and then dies again !

It make me feel a bit like a carb filling up with fuel, and as long as this fuel chamber contains fuel, the motor runs...but the chamber is not being filled again.
Stupid I know, but I can't describe it any better.

SO what do you think?
The fuel filter clogged? The fuelpump not supplying enough?
Could it also have something to do with some relay i don't know of?
oh yeah..one last thing....HEEEEELLLLLPP !!!

[Don Settergren]

Check the ignition switch. The fact that it starts upon return to position 2 on the switch makes me believe that the connection required to power ignition does not work in position 3 of the switch.

[Blacklook]

OKay Don, I'll check the ignition switch, Tx for the tip!

hmmm...however, that does not explain why the engine stalls after running for 60secs after my first succesful coldstart??

[Don Settergren]

Was the 60 second operation a one time occurrence or is it repeatable? If repeatable, you are correct, there may be a fuel delivery problem or a heat related ignition problem. When you say "first cold-start" is this a first of the day, first after an engine rebuild, first after changing the oil...?

Keep pouring out the information so we can help. Also, try to individually isolate spark, fuel, air and compression.

[Blacklook]

Hey Don,

I had the car towed to my garage, and I was able to do some further testing.

Last time i drove my C2 it was pooring like hell...and that's how i parked it.
When i then tried to start... i had this symptom i described above.

But apparently since my garage is much dryer then the metal garagebox that I have to stall one of my 911's... it seems that the dryer it got, the better it could start (??)
I used my ScanTool (a diag tool i could lay my hands on via RennList), hooked it up to the OBD plug and no sensors gave me an error. So that was good. Meaning that it had to be something more ignition related (no knocksensors, O2, idle switch, etc..)

I checked my DELCO's they were dry. Have cleaned the contactpoints of the two rotors. The distributor belt looks also good.
So..my engine runs good, cos it's powderdry.
SO...to make a long story short, I'm suspecting my coils. These are 2 Bosch (Made in Brazil) coils, and I think that they go shortcircuit when too humid...

Does that make sense?

[Don Settergren]

So you think moisture is affecting your coil. Could be! Moisture can also affect the sparkplug wires and the idle control and MAF and many other electronic items.Hoepfully you can inspect the various covers and find moisture under the culprit. Maybe even swapping parts with dry ones while the car is struggling to start might help focus you on the final problem.

[Blacklook]

Hey Don,

I'll keep you posted on what the possible outcome will be. Thanks for your tips.
I have another planned garage day in 2 weeks. It is then that i hope to install my new coils...and have the problem solved.

Regards,