Stalling - Sputtering Problems while driving
 

77 911S CIS.

Having a problem with the car almost stalling out, as if it's fuel starved, then kicks in about a second or 2 later and gives a little back fire and runs fine.

Happens at all speeds and usually during acceleration, although I have noticed it at times when I'm not accelerating.

The car jerks hard as if it's going to quit right there on the spot, then will kick in again and run ok. This can happen a few times in a row, then will run fine for a 5-10-20 minutes, before doing it again. Then I won't notice it for a day or two, before happening again.

I have noticed a small backfire when up-shifting and during hard acceleration, right at the point of engaging the clutch. Although this is not happening during the stalling out problem, I thought possibly it could indicate I'm running too rich, which may have a relation to the stalling out problem?

I bought the car about 9 months ago (66k miles) and had a pop off valve installed in the first week or so. I know those can cause problems occasionally, but this stalling problem just started up in the last two weeks.

Any ideas to help an amateur mechanic? :confused:

Thanks!
Ken

Start with your points. Are they clean and gapped right?

Joe

I second points as the probable cause. After that, look @ tuneup items, such as wires, rotor and cap, and plugs. Also check mixture and control pressures to verify WUR function.

Hey Ken,

I'm no expert and mine's an '81 SC. However, I had a similar problem early in the summer. I changed almost everything I could with no results. Then I changed the fuel filter and problem went away. Here's more info:

http://forums.pelicanparts.com/showthread.php?s=&threadid=232707&highlight=wow+fu el+filter

Good luck!
Shayne

Thanks for the suggestions guys and the link to your old thread Shayne! I was searching through the archives and couldn't quite find a similar sounding problem.

I'll give the suggestions a try and post back with my results.

Ken

Classic systems of a vacuum leak. Check that new pop valvae. Make sure it is sealed well and hasn't started leaking air. For hesitation on acceleration the Probst manuel list these probable causes:
Vacuum Leak(intake air)
Fuel injectors clogged.
Cold Start valve leaking
Air-flow sensor plate out of adjustment.
Fuel pressure incorrect.
Idle mixture incorrectly adjusted.

Good luck