My car stalled twice today! What's going on?

azasadny · azasadny's Garage

I took Helga out for a brief, spirited drive today but she stalled out twice. The car was running perfectly until this happened, no lagging or backfires, etc... I had a hell of a time restarting her, I had to crank the car about 25 times before she started again. When she did start, she revved up to 4K, then dropped down and 0 and stalled. She did this once or twice then finally started up and ran great, so I'm stumped.

This is an intermittent problem and has happened about 4 times, once last fall and three times since Easter. I can smell fuel while I'm cranking the car and the car "wants" to start and turns over, but doesn't start.

I replaced all fuel lines and vacuum hoses last summer. I haven't had time to look at anything yet and since it's an intermittent problem, it may not happen again soon. It happens when the car is at operating temps and has been running for at least 15 minutes. My car is a '74 with 2.7L CIS, mostly original except for PermaTune CD unit and Pertronix ignition. I'm looking for a few pointers to get me started troubleshooting this. Thanks!!

Oh Haha · 04-09-2005, 06:09 PM

Mine does this once in a while , too. I have found that by turning the air bleed screw a bit seems to make it work okay. I think it may be an overrich issue. I just backed my air mixture screw off a click or two to compensate for the warmer air. Just my ..02.

azasadny · azasadny's Garage

Wayne,
Thanks! I'm "glad" this happens to others, too... and not just to me. I haven't readjusted anything yet but I may take your advice. Do you make the adjustment after the car stalls? Thanks!!

Paulporsche · 04-09-2005, 06:34 PM

Have you checked your points/dwell?

Also, a lot of posters have complained of run problems caused by their Permatunes.

azasadny · azasadny's Garage

Paul,
My points were replaced with the Pertronics unit, but I'll check that too. Do I turn the air bleed screw counterclockwise to lean it out a bit?

Paulporsche · 07:03 PM

Sorry, missed the Pertronix reference.

The air bleed screw is on the side of the throttle body. It is for idle speed, not mixture. Clockwise = slower rpm.

Mixture is set via the 3mm Allen screw accessible through the hole @ the top pf the mixture control unit. Clockwise (as seen from above) = richer.

Have you checked things like wiring (incl grounds) fusebox, fuel pump relay?

azasadny · azasadny's Garage

bumpity-bump

Oh Haha · 04-10-2005, 03:41 PM

Did you take Helga out today? If so, did she stall?

azasadny · azasadny's Garage

Yep, I drove about 5 miles and warmed her up, then filled the tank with fresh gas and she died at a stop sign down the street from my house. I leaned out the mixture by a full counterclockwise turn and no help. She wouldn't start until I cranked at least 25 times, then she started right up and ran great around the block and I put her in the garage. I am going to take her to a local German car mechanic this week becuase I don't have a clue as to the problem. Very weird...

Oh Haha · 04-10-2005, 05:41 PM

Too bad. Maybe trained mechanic will be able to spot the trouble right off the bat. Let us know what happens. I don't know how different our motors are but no sense in making it worse by trying a bunch of" try this and try that".
See ya around,

azasadny · azasadny's Garage

Wayne,
Thanks! The frustrating thing is that the car runs so well, no missing or stumbling whatsover, then suddenly dies and refuses to start until I crank at least 25 times. The idle speed problem has been around for as long as I have owned the car (almost 3 years), but now every time I take the car out, she dies and won't start again. Time for a pro to look at it and see what I'm missing. Thanks for your help!

ruf-porsche · ruf-porsche's Garage

When she stall next time check for a spark to see if it's ignition or fuel. Could be that Perma-junk that you have in the engine.

Paulporsche · 04-10-2005, 07:13 PM

If you search you will find lots of talk about Permatunes. As I mentioned before a lot of members have had problems when these things get hot.

Have you gone through the checks for spark and for warm control pressures/WUR?

Have you checked your distributor for advance . Have you made sure the distributor is not turning in its mounting?

azasadny · azasadny's Garage

If it is the PermaTune, what is the replacement? Three years ago, the Bosch units listed for a ton of $ and so I replaced my PermaTune unit with another. What are my options? Thanks!

911teo · 04-11-2005, 05:59 AM

I had a similar issue with mine... Does it smoke at all? On mine it was a cylinder head sensor. Basically the car was running too rich as the DME was trying to compensate for the wrong reading from the CHT unit.
If I let the car stay overnight it would start easy... but as the time went by it got worse and worse and would not hold idle.

I hope this helps. Good luck with the car

neiltorda · 04-11-2005, 06:18 AM

i had the same problem last year with mine. It was the permatune.
I got a used Bosch unit from 20th St. auto here in Phoenix for $50.00

He's got a bunch of dead 911's behind his shop, i just went out there and took one out. Got in my car to go home, and it wouldn't start. Pulled out my tools, swaped the unit in his parking lot, and haven't had another problem with that since.

neil

azasadny · azasadny's Garage

Neil,
Thanks, I guess I should start looking for a used Bosch CD unit. It would be good to have a back-up unit even if the PermaTune isn't bad...

ruf-porsche · ruf-porsche's Garage

Quote:

Originally posted by 911teo
I had a similar issue with mine... Does it smoke at all? On mine it was a cylinder head sensor. Basically the car was running too rich as the DME was trying to compensate for the wrong reading from the CHT unit.
If I let the car stay overnight it would start easy... but as the time went by it got worse and worse and would not hold idle.

I hope this helps. Good luck with the car

Guys AZ has a cis engine not a DME.

KobaltBlau · 04-11-2005, 08:09 AM

Just to clarify: pertronix makes a points replacement that has worked well for me (in a VW dizzy, not 911), I do not think that they are in any way associated with permatune.

I'm not affiliated with either company.

just be careful not to wire the pertronix in backwards, at least on the older ones it could blow them.

911teo · 04-11-2005, 08:44 AM

Quote:

Originally posted by ruf-porsche
Guys AZ has a cis engine not a DME.

Now I look silly, don' t I? Sorry for not keeping my mouth shut.