clueless and miserable - dead 2.7 911S

[EspenReiss]

My 911S, 1977, with a 2,7 engine is giving me so much misery these days. She starts up ok when cold - then runs fine until I hit the first roundabout - and as soon as I let up the gas she dies hard. An stays dead until cold.
The coil is new, the alternator is new, the distributor is new (electronic - changed two months ago), spark plugs are new, all vacum hoses are gone over, all electrical cords for earthing is tried and found fine, fuel pump changed last summer, fuel filter changed.

My mechanic thinks it is an electrical problem as the spark seems low - while his boss thinks it is a gas problem - for me it is becoming a financial problem.
Nobody thinks it is the warmlaufregler - the worm air regulator or the gas storage thank for cold starts.

Oh misery!It worked fine for 500 miles -and then she has not run properly once.

Any suggestions on where to start? Any ideas will be appreciated.

Yours Espen

[boyt911sc]

Originally Posted by EspenReiss

My 911S, 1977, with a 2,7 engine is giving me so much misery these days. She starts up ok when cold - then runs fine until I hit the first roundabout - and as soon as I let up the gas she dies hard. An stays dead until cold.
The coil is new, the alternator is new, the distributor is new (electronic - changed two months ago), spark plugs are new, all vacum hoses are gone over, all electrical cords for earthing is tried and found fine, fuel pump changed last summer, fuel filter changed.

My mechanic thinks it is an electrical problem as the spark seems low - while his boss thinks it is a gas problem - for me it is becoming a financial problem.
Nobody thinks it is the warmlaufregler - the worm air regulator or the gas storage thank for cold starts.

Oh misery!It worked fine for 500 miles -and then she has not run properly once.

Any suggestions on where to start? Any ideas will be appreciated.

Yours Espen

Espen,

Does the car start now? If it does, warm up the engine for 15 mins. and turn it off. Re-start again and run for another 10 mins. Don't drive the car but try to replicate the problem/s by running the engine. It would be nice if you have a fuel pressure gauge hook up during the test to monitor the fuel pressure.

If the problem is caused by the fuel pressure it is a simple test. But if the problem is electrical or temperature related, then you have to get the engine completely warm up and observed till the problem occurs. If you could replicate the problem during your test/s, check if you still have ignition sparks and read the fuel pressure.

Do you still have CIS? Keep us posted.

Tony

[kodioneill]

Well, don't lose faith. 1977 911s. It could be as simple as a blown air box or a pop off valve that is stuck open or loose. There are many things that can cause this issue. Could be vacuum leaks, fuel pressure, warm up regulator failed or not getting power (causing a very rich condition). It's most likely a vacuum leak or a fuel pressure problem. What have you done to the car lately? Did this just happen?
How many miles are on the car? How about some photos of the engine close up?

[EspenReiss]

Thanks for your replies.
The car has driven 115000 miles - I bought it in Flordia and drove it straight to California - that is via several stops at different Porche garages. At one point I could not start the car and it did not idle - while I tried to find the down town Porsche dealership in and garage in the middle of the lunch rush in New orleans. As soon as I pulled into the dealership the car started and run perfectly 15-times in a row. An hour later on the road out of New Orleans it was running nice, but would not start after a brief pause. Red Line in El Paso gave me a new coil and fixed the brakes. Starting and running nice. Died in the desert to hours out of El Paso. At Precion Motion in Riverside just outside LA - the Kravik family worked on the car for three days - changing anything we could come up with. Car run as new from LA to Berkeley and along the coast back to LA and Riverside. Running like new, everything sparkling fra Riverside to Long Beach for shipping the car back home to Norway. Arrived in Norway in a snowpile and minus 20 celcius - started like a charm - drove like a true soldier for 500 kilometers in heavy snow. Just outside my hometown Stavanger she just stopped in a roundabout and would not start. Now she is in the garage given a new starterring - I wore the old one out - new clutch - all vacum hoses checked out - all groundings checked - starts but dies. I will do as you say - but first I will install a new preassureacumulator. I thought this only did something with cold start, but I learned today it works all the time. And I will monitor the co-output.
No I know for sure it is not the pop off, and I don't think she is to rich - the sparkplugs looks fine and the exhaust is white and mostly invisible. We will use some sort of gauge to check the fuel pressure later today.
I'l keep you posted. If nothing works I'l make a video with closeups and sound so you can observe the problems. Besides - I found a guy up the coast with 5 old 911's and experience to match. So I am much less miserable today than yesterday.
Yours Espen

[T77911S]

to elaberate on what tony said,
try to get it hot, might take a while with that temperature, but let it run, dont drive it, and see if it cuts off. if it does, and it will not start, check for spark. if the motor starts surging before it cuts off, you are running too rich, which i suspect.
you can even pull an injector or 2 and check for fuel by lifting the sensor plate with the key on. dont do it too long as the others are dumping fuel into the engine. just a quick check.
you could even try to restart it after doning that.

check for 12v at the connector on top of the WUR.
you really need to get gauges and check the control pressures.


electronic dist in a 77? is that aftermarket? was this put in after your problems started?

[Howard M]

Hmmm...."electronic distributor"? What's in there? I had an MSD with exactly the same symtoms. Varified bad by MSD. A new one cured all issues (I now carry a spare).

[kiwiokie]

You mention roundabouts. Perhaps some crud being picked up out of the fuel tank when the fuel sloshes around?

[ant7]

hi,
if all other [logical] sugestions fails,
It could be an electrical fault in the wiring looms to the engine, ie; when engine is moving in a paticular way the fault is showing up, for eg, when backing off' the engine will move/tilt one way and on accelaration another, this could be why it seems to happen when your slowing to roundabouts etc.
Just a thought.
hope you get it sorted.
Anthony.

[Jim Sims]

"Nobody thinks it is the warmlaufregler."

I have a 1976 911S with CIS and my car would behave the same way; it would start cold and then fail to run after getting a short ways down the road. It would not restart until cold again It was the warm-up regulator (WUR or warmlaufregler); the cold start pressure was sufficient to enrich the fuel/air mixture to enable starting and running but as soon as the car warmed up the WUR would lean out the mixture due to incorrect pressure and the car would die. The WUR was replaced with a rebuilt unit, the car's mixture (CO) correctly adjusted and the problem was solved.

The Porsche CIS parts are too expensive to solve problems by "trial and error" replacement of parts based on hunches or "thinking" without data. Get a CIS pressure test rig (or engage a mechanic with one) and run the tests, compare pressures with specifications and consult a troubleshooting guide by Porsche or Bosch.

Good luck. Jim

[47silver]

my 75 would run good then shut off and when cold would start again. I found (after quite a few nasty words) that the black wire that was connected to the points was close to the distributor shaft, when the car would heat up it would touch the shaft and eventually was worn bare. when the car was cold it would not touch the shaft and the car would run..

if that is good then you have to check the pressures like tony suggests.

[EspenReiss]

Thanks Porsche-gurus - she now runs nice thanks to you! The WUR was cleaned, the fuel mix enriched, and several vacum hoses mended. She still starts hard. It might just be something with the fuel pump - it seems not to run until you actually starts the car. We can her the rely tick so it must be a rotten connection somewhere.

Thanks - and yes - I feel so much better with her running. No more misery.

Yours Espen

[ossiblue]

Originally Posted by EspenReiss

Thanks Porsche-gurus - she now runs nice thanks to you! The WUR was cleaned, the fuel mix enriched, and several vacum hoses mended. She still starts hard. It might just be something with the fuel pump - it seems not to run until you actually starts the car. We can her the rely tick so it must be a rotten connection somewhere.

Thanks - and yes - I feel so much better with her running. No more misery.

Yours Espen

The fuel pump on your 77 is designed not to run until the starting circuit is engaged so not hearing the pump running with the ignition switched on is normal. The fact that the pump (and engine) run normally once the cold start is overcome tells you the pump circuit is operating correctly. This doesn't mean the fuel pump itself is perfect and not a problem, just that the electrical circuitry is operating properly.

Please detail your exact problem with the cold start as there are several possible causes. Now that you have solved the initial problem, you can focus on the cold start.

[ivangene]

I am willing to relieve you of the headache....are you ready to ship it to me in the US yet ....



keep trying, its something simple - I have seen it too many times and remember in the end you will be SOOO SMART about so many things that it IS NOT

best of luck