80 911 will not start

[retireduper]

My 911 SC stopped running after a short trip, and after one restart, whichsounded very rough, it quit and I have not been able to restar it since. The areas I have checked are as follows:
1. jumpered the fuel pump and got it to operate.
2. checked the air flow sensor operation, and when the sensor plate is lifted the fuel pump does in fact run.
3. checked the CDI plug for voltage, which it has at terminal 15
4. replaced the distributor cap and rotor, as it looked worn on the inside, and had carbon buildup.---No help
5. Ran a check for spark, using the #4 sparkplug which I removed and grounded it to the frame. Had strong spark, and CDI had the usual high pitch whine.
6.Checked the air flow sensor control plug, cleaned the terminals, and checked for wire breakage, but could find none.

I now suspect a short somewhere, however I have checked the wiring at the fuse box, removed all the connections, fuse, and cleaned and replaced with no change. I
am now stumped. One thing I could not check was a "RPM Limiter switch". This wasbnoted in the Bentley manual, however I don't know where it is or if it is.
This one has me pulling what's left of my hair out, and I would appreciate any help anyone on the board could give. Thanks
Chuck'

[derRITTMEISTER]

did you drive through heavy rain?? I noticed this to be the #1 problem with my car and either a no start or it dying and being unable to restart...
if you drive through rain/leave the car parked outside, you could have moisture in a variety of places (as the distributor cap, ignition, relays, ect. are VERY exposed to moisture inherent in the 911 design). there's lots of helpful posts on here to protect against moisture on here, its an intermittent problem that this very difficult to diagnose to one component.
best of luck
andy

[psalt]

Hello Chas,

How much fuel is in the tank? The 911 gauge is not very accurate at a low level, and many have been fool by this. If you don't know and the gauge is below 1/4, put some fuel in the tank before rebuilding the engine. If you have good spark, focus on fuel. On your car, the safety circuits, rev limiter, alarm, air flow switch, all shut of the fuel pump circuit, not the ignition. I would put fuel in the tank, remove the air filter, turn on the key, manually push up the air flow sensor for 3-4 seconds. You should hear the fuel pump come on and the injectors buzz. If you ran out of fuel, this will purge the air, and this will test the air flow switch. If you don't hear the pump run, jumper the fuel pump again and try to start the car.
__________________
Paul

[retireduper]

Paul,

You won't believe this but I checked my gas tank and although it said just about 1/4 full, I decided that I would take a chance and I put an additional 2 gallons in. The starter cranked for about 10 sec's. and then caught . It ran a little rough for about 15 sec's but then it purred like it should.
Thanks again for the input on adding gas, and also thanks to all of the Pelicanites who offered advice. I certainly appreciated it , and Hope I can do the same for someone at some point . You can't beat this forum.
Chuck