Engine cut out this morning...

[emcon5]

Car is an 82 911SC with stock CIS.

Coming to work this morning, driving along, fully warmed up, constant throttle, about 3000rpm in 3rd, the engine cut out. I looked at the tach and saw the needle dropping like a stone, it almost got to zero when it returned to normal and power came back. This is the first and only time this has happened.

I don't know if this is something altogether new, or a new symptom of an ongoing problem.

I have been chasing an intermittent cold start problem, the symptoms of which are engine cranks and cranks, and smells like gas. I had my wrench check the CIS pressures for me, and he adjusted the WUR because the cold control pressure was off, causing it to run way too rich when cold. After this adjustment, the car has much better manners when cold, but I still had a problem on cold start a couple times. I replaced the Thermo-time switch with a known good one to try and eliminate it as a problem. I haven't had any starting problems since then, so I was thinking that it may have been the cause, making the cold start valve to pump whenever the starter is engaged, causing flooding if it doesn't start right away. This has only happened one time when the engine wasn't completely cold (drove about 5 minutes to get breakfast, after eating I came out and it wouldn't start, same symptoms, cranked off and on for a minute or so, no luck, waited a min, started on first crank).

Possibly related, yesterday on the way home, I had the air conditioning on just after leaving work, and I stalled the car at a red light (my fault, lower idle from A/C on, too quick on the clutch). It was difficult to restart, but when I turned off the A/C it fired right up.

Other symptoms which may or may not be related, intermittent ping under full throttle load, >3000 rpms with engine fully hot. I also found out when I got it smogged a couple months ago that the tach is off slightly, and reads about 200 RPM slow. It passed smog with flying colors. Timing is set to spec, and mechanical advance appears to be working properly. I only use Chevron Premium gas. Oil consumption is high, at 1 qt/300 miles or so, but it doesn't smoke and the plugs look fine.

Other things I have done when trying to solve the cold start problem:

Replaced the coil (leaking black stuff), new OEM part.

Tested the Permatune box using the instructions on their web page. It passed all the tests.

Checked the green wire on the distributor. Tested OK.

Cap, rotor and plug wires are about 1 year/10Kmiles old. Spark plugs are a month old.

Any ideas where to look?

Thanks,

Tom

[wckrause]

How about your fuel pump relay?

[MTH]

Tom,
I had a similar problem, turned out to be the fuel pump. Hope this helps.

Mike

[emcon5]

I forgot to mention, the Fuel pump is also new. Replaced about a month ago because it was whining like the BMW guys at the Open Track Challenge.

Bill, the fuel pump relay is old, and that did occur to me but I talked myself out of it. If it was fuel related, would the tach drop like it did? I would think that symptom alone would point to an electrical problem.

Is my logic screwed up on this?

Tom.

[john70t]

I had my old VW cut out randomly several times, and after taking it to a shop and having both fuel pumps replaced to the tune of $500: it did it again later only when warm.
I took the relay cover off and found the green circuit board was half brown. Doh!

Another time the 911 engine cut out completely and later found a distributor wire rattled loose and fell off.

These probably aren't related to your problem but you might want to do a "wiggle" test: i.e. run the engine and start playing around with the pump/ecu/grounds/relays to double check the connections.

[emcon5]

Thanks for the replies.

Well, it appears the culprit was the CDI box. It was a little hard to start this morning, and again when leaving work. On the way home, it died, same symptoms as before, tach dropped to zero, but this time, it didn't come back. I coasted to a stop, and tried to restart, but it wasn't happening.

Luckily (again) my wrench was still at work, and his shop was about 500 yards from where I broke down. He showed up with a stack of CDI boxes, 2 Bosch units and a Permatune. We swapped them back and forth a few times, every time one of his was plugged in, it would start. Every time mine was plugged in it wouldn't.

At the moment, I have one of his Bosch units on there, until I can find a replacement.

Anyone got a good Bosch 6-pin CDI box they don't need, or a bad one I can use as a core for a rebuild?

Thanks,

Tom

[Chuck Moreland]

Tom

Have you considered an MSD? I picked up a 6al for about $100 on ebay that I use for my truck .

[emcon5]

The thought has crossed my mind. I understand it is fairly straightforward, my big concern is where to mount the big red box.

I need to reread the the Chapter in Waynes book.

I must say, when I got in the car this morning, and heard the faint whine of the Bosch box when I turned on the key, it made me pretty damn happy to know that this this ongoing pain in my ass is nearly resolved.

Tom