car stalls when oil cap is removed.

[Algernon]

I got a tank full of non-ethanol gas (rare in Colorado!) and now the car runs rough. When I remove the OIL filler cap - it stalls!! Any suggestions - too hi/lo octane? Add fuel drier/power booster additive? Just run it and refill as soon as possible?
Thanks.

[toddu]

That's a good sign (no vacuum leaks). Your missing the restrictor in the return line to tank filler neck.

Todd

[boyt911sc]

Originally Posted by toddu

That's a good sign (no vacuum leaks). Your missing the restrictor in the return line to tank filler neck.

Todd

Todd,

Hope you are correct. But a properly set CIS should not stall or stop running after removing the oil filler cap. It would drop the idle speed down approximately between 150 to 200 rpm (which is a good sign) or stop running (bad news). In this case, I would suggest to inspect the breather hoses or test for vacuum leaks in the system.

Tony

[toddu]

My bad, responded too quickly. Yes, literally stalling is not good.

Todd

[Reiver]

It could also be you are running too rich...so when you remove the cap and it lowers your rpm it cuts out.
What is your normal rpm that you set for idle?

[Algernon]

It normally runs around 800 rpm when warm. I don't think dirty gas, as it runs fine when driven above idle. I'm guessing the problem is the gas, either too high(?) or too low octane. If idle is suddenly too rich, does this imply wrong octane value. Gut feeling is its too low, so maybe I should add some octane booster to the tank until I have used enough to refill tank with 'good stuff'? Am I on the right track here?

[ThomO]

It is the restrictor in the oil line I have seen lots of SC's do that.

It is a cheap easy fix. Our host sells them.

[RedCoupe]

Originally Posted by Algernon

It normally runs around 800 rpm when warm. I don't think dirty gas, as it runs fine when driven above idle. I'm guessing the problem is the gas, either too high(?) or too low octane. If idle is suddenly too rich, does this imply wrong octane value. Gut feeling is its too low, so maybe I should add some octane booster to the tank until I have used enough to refill tank with 'good stuff'? Am I on the right track here?

It isn't anything to do with the octane rating of the gas. Octane numbers just quantify the ability of gasoline to resist pinging when the engine is loaded. Different octane fuels should behave similarly when the engine is idling. On the other hand, the gas with alcohol added will behave a bit differently than straight gasoline, but if anything I would expect you to notice better running with the straight gas. Any chance the non-ethanol gasoline has been stored for quite a while and perhaps has some water in it?

[Dave Colangelo]

Are you removing the cap right when you start the engine or after its warm. My SC drops idle when the cap is removed but the oil needs to be flowing and a bit warm. I once made the mistake of pulling the cap off right after I started the car cold, the car stalled out but that is the only time it ever did that. I now never remove the oil cap with the engine running until the car is warm. You may be running oil that is a bit to heavy or as mentioned it may also be your oil line restrictor.

Regards
Dave

[bareflanks]

I have the same problem after removing/cleaning my oil tank on 88 911. All hoses/vacuum lines are installed correctly. Not sure if the recirculating air valve has anything to do with it; can someone advise where the 'restrictor' in the oil line is located and does this apply to non-SC motors also?? Many thanks for the help.

[Bob Kontak]

Originally Posted by ThomO

It is the restrictor in the oil line I have seen lots of SC's do that.

It is a cheap easy fix. Our host sells them.

I doubt this. The restrictor is a metal plug with a hole in it just upstream of the oil tank in the hose that comes from the back of the bellows. Bridge between the air sensor and throttle body.

#1 - who the hell knows it is there?
#2 - why would it fail?
#3 - Who would remove it?

Refer to boyt911SC's post.