911 3.0, starts better runs rough
 

Question: What next?

1980 911SC original engine. Looks like basic maintance has been done, not much else.

My first problem has been cold start.. car will start ad run for 2 sec and then quit. after 4 -6 starts car will run on its own but very rough. This problem has always been the same. After warm up (2-4 min),some times the car runs ok and other times runs real rough. By rough, I mean missing cylinders, backfires, hard to get the RPMs up. once I get the rpms over 3000, runs ok.

I have replaced: plugs,wires,cap,roter and the warm up regulator. The fuel pump looks new, I did notice that it is a long neck pump with the check valve inside. The gas in the tank is new.

I have a new check valve and accumilator I have not installed. starting to sound more like a fuel injection problem or air sensing.



I need some help with this one.

Thanks
Phil

Maybe your injectors are dirty and do not spray well at low rpms. You can pull them out one by one and let them spray in a glass jar while cranking. If that is the case, a bottle of techron in your next fuel refill might help. You could also have a vacuum leak somewhere in the CIS (boots for instance). You can detect that by a surge in rpms if you spray some carb cleaner where the leak is. You can test if your fuel accumulator is bad by unbolting the bottom return gas line. If gas drips from there, it is shot. Be careful with fuel...

Aurel

has the dizzy been serviced lately?? i.e. the few drops of oil down the main shaft and all moving freely in there??
Techron is great stuff... put in 1 or 2 bottles NOW to possibly eliminate semi clogged injectors a/o fuel dizzy
probably a combo of things... make sure to also do as Aurel suggests
Good Luck!
Bob

I have exactly the same problem. Turn the key, car starts, then runs rough for a few seconds, then idles fast for a few seconds then runs great, no problems. I am down to the Aux Air Regulator or the Warm-up regulator. All else is OK.

Try this.

Remove the electrical connection to the warm up regulator (left side of the engine), and see if it makes a difference. If not, replace then remove the hose from the Aux Air Regulator and spray some oil in it. Put the hose back on and try the next morning and see if that makes a difference. I admit, and expect to get yelled at by this crowd, but I am shooting in the dark a little here. If none of this works, then all thats left for me is the fuel distributor and that was new 8 years ago but only 3000 miles (car sat for a 7 years when I bought it and brought it back to life).

Good luck

has the dizzy been serviced lately?? i.e. the few drops of oil down the main shaft and all moving freely in there??
Techron is great stuff... put in 1 or 2 bottles NOW to possibly eliminate semi clogged injectors a/o fuel dizzy
probably a combo of things... make sure to also do as Aurel suggests
Good Luck!
Bob