Porsche Repair: 78 911SC Cutting out, fuel pressure gauge, k jetronic

Question
Last week my 911 started making a vacuum sound
from the airbox. That was before I lost power
over 2000 rpm.  I haved checked the ignition &
the CDS is whistling and I replaced the coil pk.
My 78 has "K-Jetronic injection." I went to check
the fuel injection and replaced the fuel filter,
(partially clogged) and I'm getting fuel flow
from the pump but I don't have a pressure guage
to check it.  Also, when idling, the exhaust is very HOT. Yhe Haynes manual I have leads me to
believe that it has something to do with the
fuel distributor, but it just says to take it to
a Porsche dealer...There isn't one anywhere close
HELP!

Answer
Hi Chuck,

Sorry to hear about your problems.  If you are without a mechanic's help you'll really need a fuel pressure gauge with a valve made for CIS testing.  If the problem really is related to the fuel distributor, the only way to diagnose it is based on fuel pressure.  In the meantime, there is one test you can do right now to check the fuel pump action.

I'll describe the procedure and if you need more detail or clarification, please follow-up with me using the all-experts system.  

You are measuring the fuel pumped from the tank through the fuel distributor and you will catch it just before it begins its return trip to the tank.  Disconnect the return line at the rubber hose and set up a safe and secure way to catch 1 or more liters of fuel.  Energize the fuel pump by placing an 8 amp fused jumper wire between the fuel pump relay socket terminals 30 and 87a.

Run the pump for exactly 30 seconds.  You should pump 1 liter of fuel if the pump is working fine and there are no obstructions.

Let me know whet you find out.

Dave