2.7L CIS Engine Hesitation Question

[Ruben911]

Need help figuring out problem with engine hesitation. Two weeks ago I performed a valve adjustment on my 1976 911S. I also changed the fuel pump, fuel filter, plugs, points and rotor. The car ran great for the first couple of days, in fact, I believe I picked up some additional HPs. However, I now experience engine hesitation when I go above 3000 RPMs. I double checked everything, points gap, plug connectivity, etc and I can't see anything unusual. One question I have is that when I cover the air intake with my hand, I don't experience any affect on the engine RPMs. Is this normal? I would expect that if I block the air flow, that the engine would drop RPMs. Does this mean that I have an air leak. Also, I see a 1/2 inch OD hose coming from the front of the engine compartment but it is not connected to anything. Any idea what this hose might be for. Thanks in advance for your advice.

Ruben911
1976 911s 2.7L

[pjv911]

The only thing to do is backtrack your work. If the problem wasnt there before chances are you did it. The line you speak off could be for the air pump intake? or brake booster(think that started in 77`). Make sure you have a good seal on the fuel pump intake side you could be sucking in air bubbles(DID THAT MYSELF ONCE).

[grant lyon]

Do you have a ~1/2 hose sticking downward into the top of your warm-up regulator?

Also, suggest you check vaccum hoses *carefully*. I find that mucking about around the original German hoses (P-Cars, BMW ...) tends to cause cracks -- then air leaks. My mechanic was good enough to just replace several of my hoses the last time we had stuttering problems.

Also, more expert people that I can help -- but, points from Bosch are hopeless these days. My mechanic clued me in to this. Changed to Pertronics and solved a major portion of my stutter problems -- outside of air leaks.


I have a '76 too.
Good luck.

[Ruben911]

Thanks for the feedback. I will be doing another check on things I modified and will be looking at the vacumn hoses carefully when I get a chance this weekend. I'll also look at the fuel pump installation allthough I don't see any fuel leaking from the pump. The warmup regulator has all the required connections. I still would like to know why when I cover the air intake with my hand and depress the trottle, the engine still revs up without much hesitation. Is there another source of air which I am not aware of? Finally, how can I tell if I have the right fuel air mixture? Thanks

Ruben911S
1978 911 2.7L Stock