Ignition on 911T

For those just joining me on my adventure, I am the new owner of a 1973 911T. Got it on sunday, been driving it to work all week. Sometimes pushing it to work...

On Tuesday and on Wednesday nights on the way home from work the car just flat out died. No sputter, no coughing or anything. Driving along at highway speeds then nothing. While coasting to the breakdown lane both times, the car restarted before I had to stop and I was able to make it home.

This morning, things took a turn for the worse. I got in to downtown Minneapolis and the car died, same routine. I fiddled with this and that (namely the distributor, checking points gap and electrical connections, etc). About 10 minutes later the car started right up and took me a full 3 blocks before dying again. Rinse and repeat previous jiggling of wires. Car died again 2 blocks from my parking lot so I pushed it the rest of the way (much to the delight of passersby).

At lunch I went out to the car and it fired right up. I shut it down and went back to work. After work, it fired right up and made it 10 miles before dying the first time (at speed this time). It died once more 4 miles later but the final start got me home.

Now it should be noted that when running the car sounds great (for the most part) and runs strong. When it dies it is a complete shutdown of the motor, all other ignition KEY related items are still functioning.

The car has a permatune module replacing the CDS unit and it is my suspicion that the problem lies somewhere in the ignition system. I am getting fuel to the cylinders even when the car won't start as you can smell it as the engine floods. It also appears to be somewhat heat related as the cool mornings were the mornings I made it to work without incident and the warmer afternoons and the very warm morning and evening today were the problem times.

I drove the car home on Sunday (150 miles or so) without any problem at all.

Ok, ideas? I just got my Haynes (poorly reviewed but it doesn't look tooooo bad) manual from Amazon today and the CDS system makes sense to me but there is no enough detail there to make me confident. I will be running some checks on various parts with my v/a/o meter tonight to see what I can see. Of course the car is running right now so the results will probably be fine...

Cheers and thanks again,

Dan

Replace your fuel pump fuse. I've had my car not start twice now due to bad fuses. They appeared good but as soon as I replaced them the car fired right up. This would be a starting point anyways.

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'76 911S

'80 924 M471

[This message has been edited by Gary Peters (edited 09-29-2000).]

Check out the Permatune website. They have some troubleshooting guides. Sorry but I can't remember where I found it.

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'76 911S

'80 924 M471

[This message has been edited by Gary Peters (edited 09-29-2000).]

On my 70t, this happened quite a bit. I did the same thing that you are doing. Ignition first. But really all my problems were fuel related. I even smelled gas and thought it was flooding.
I tried everything with the fuel system also. Rebuilt carbs. Changed: pressure regulator, fuel pump twice, fuel filter, etc. It turned out to be the fuel tank and lines, mostly the fuel tank. Too much buid-up of junk over the years. I would drain the fuel tank, clean out the mesh filter on the tank, blow out the fuel lines, put it together again. I ended up resealing the inside of my tank, also. Worked like a champ after that. Ed

Found the permatune troubleshooting guide at www.perma-tune.com/tech/911.htm I'll do the bench test that they recommend and bench test my coil as well. If those pass I'll start on the fuel system (which was my first guess). I still think it's ignition related based on the complete suddenness (hmm, probably not a word) with which the motor just STOPS.

Thanks for the ideas so far.

Cheers,

Dan

Change the fuel filter and go for a test drive before going infront of the masses.

Randy Jones
1971 911

Dan,

I doubt if your sudden cut-offs could be fuel delivery problems, as you said nothing about sputtering!

My general experience says Perma-Tune or Bosch CDI-units do not develop intermittent failures, but it is possible, just not very likely. A much higher probability is for the problem to be inside the distributor, and related to the rotating point plate:

1. The bare copper ground wire can break at the spot weld to the point plate, causing intermittent lack-of-spark problems.

2. The tension/limiting spring and holder for the ball bearing can loosen and cause both random and temperature-related intermittent loss of spark.

If you think you will have an assistant available who can crank the ngine while you troubleshoot in the engine compartment, make up, or scrounge a sparkplug lead, and carry a spare or old sparkplug with you connected tothe 'test lead' ... when it dies, go to engine, pop the center wire out of the coil, connect your test lead, ground the body of the test sparkplug, and have assisitant crank engine and observe whether spark gets to the output of the coil. Also carry a commercially-made 12 Volt test lamp, or build your own, and if there is no spark in previous test, remove the igniton trigger wire on the side of the distributor, connect one end of the test lamp to a fuse on the Relay/Regulator/CDI-unit console, and the other end to the trigger connector on the side of the distributor ... and have your assistant crank the engine. Blinking test lamp tells you the distributor is putting out good ground pulses, and that either wiring or connector problems exist, or that the Perma-Tune unit or its' power source is the problem. If you have a multimeter, VERY CAREFULLY check the Voltage between terminals B and D ... less than 11.5 Volts is unacceptable.

There is a full-color Schematic of a '73.5 T CIS model at the following URL:

http://www.pelicanparts.com/911/911_Parts/911_electrical_diagrams.htm

The CDI-unit/distributor/tachometer/coil wiring is the same for ALL '73 models, so that part of the diagram at the above link applies to any model you might have.
model you might have! Good luck!

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Warren Hall
1973 911S Targa

It happened to me ....I had a permatune unit spent hours on my 88 930...after everthing including all rewiring mods to fuel circuits via pelivan bulletin board...MINE was intermittant with no ryhme or reason.....changed to bosche and everthing went away..all the stalling at expressway ramps etc etc...turns out the voltage regulator was the culprit..I had followed the permatune tech session....i even disconnected the factory alarm system....hope this helps....jer

I've had a lot of experience with Harleys, lawn mowers and other such complicated high tech machinery. The symptoms you describe are found 90 percent of the time in fuel delivery.Sludge is pushed against the exit of a fuel filter or jet opening and cuts off your fuel. After a rest it settles back down untill pressure pushes it back up there again. Just like what you describe. Check it out.