Porsche Repair: Backfiring and shuts off without notice, vacuum lines, vacuum line

Question
Dave,
I have a 1981 911 SC Targa.  On occasion I will be driving and the car will backfire.  On other occasions the car will just shut off.  I takes a few times turning the motor over before it will start again.  Other than that the car runs great.
What should I be looking for to correct this problem?

Thanks,
Pete

Answer
Hi Pete,

This is a standard, stock answer because most backfires are vacuum related.  If the problem appears intermittent it's likely there's a vacuum line that is starting to fail.  This means there's a tiny and likely invisible leak.  As you might imagine its the hardest to find.

My recommendation is to replace all the vacuum lines.  If you remove and carefully replace each one you may find the culprit.  Even if you don't find a"bad" one, you will have the confidence the lines are tight and intact.

Dave