1981 911 SC engine cutting out when warm

[haveacamper]

Good Morning, afternoon, evening

i have been using this site for the last coupleof months but found myself joining due to a problem i have with my engine.

THE BACKGROUND
I have a 1972 crossover camper that i am currently converting to run a 1981 911 SC 3.0L porsche engine. the conversion is part of a full on restoration i am doing. I have recently re-wired the whole bus due to the very poor rats nest of work arounds the previous owners have done.

i fired the engine up a couple of times for about 30second spells with no problem. i was working on the bus again last night where i was going to check the oil pressures and temperatures and check for any oil leaks etc when i ran into my problem. i ran the enigne on a fast idle about 1800rpm when i fired the bus up for about two minutes, but when i started blipping the throttle the engine started spluttering and then cut out.

I then tried to fired it up, but the engine just cranked. when i left it to cool back down and tried again it would fire up and then it proceeded to cut out again but this time without any throttle.

i do not have the cold start enrichment valve connected as i have the vw starter and only have connections 30 and 15. i believe this enrichment valve should be connected to the ballast resistor and only works on start up. for this reason i have decided that this is not the problem.

i believe i have fuel and spark so i am thinking it may be something to do with the warm up air circuit or the warm up vacuum fuel conpensator??

i have no reason to believe that this is not wired up correctly, but i would welcome anyones ideas what may be the problem.

NaFe

[Bob Kontak]

How is the camper running now? I have an 81 SC and do all of my own work. Not an expert, just have the ability to endure long periods of frustration. :-)

Look for air leaks past the point of the air sensor. Even though you may no think there is one there may be one. Use the starting fluid trick and spray it on the intake runners, around the airbox, where vacuum hoses meet, etc. I like the starting fluid vs carb cleaner. Carb cleaner eats stuff. There will be an increase or decrease of RPM when you find a leak.

It is critical to have "rest" pressure in your fuel lines for restart when warm. Get the tester from JC whitney. FUEL INJECTION TESTER FOR CIS-K-JETRONIC BOSCH SYSTEMS - JCWhitney

If you ran the engine for two minutes you may have warmed it up enough for some of the cold start gadgets to back off of the rich mode but not warmed it up enough to not need the cold start injector. Make sense? Perhaps at this stage if starting fluid can fire it up then you are getting closer to the problem.

Back to the warm up regulator. If all else is perfect and your control pressure is too high your engine may be starving for gas once it warms up some. Get the tester and check it out. There is plenty of data in the forums on this. I have not experienced this problem (stalling WITH having spark) in my 15 years of ownership, and again, I am no expert.

Best of luck

[Bob Kontak]

Suspect our host may blot out the reference to another retailer. If PP has the CIS tester get it from them.