80 911 -no start
 

I need some help. After a short ride last Friday, my 911 died as I was pulling into my garage. I tried to restart it and when I did, it ran rough and finally stopped. I have not been able to start it since. I have checked out the CDI as okay, installed new distributor cap and rotor, and checked the fuel pump. The fuel pump will run if you jumper it across the terminals in the relay socket. I have checked the air flow controller and it also operates the fuel pump when you lift the actuator arm, and it stops the fuel pump when you release it. I am at lost as to what else it could be except a short somewhere. I have checked the fuses and wiring at the block but have not found any open or broken wires. The only thing I have not checked is what the Bentley manual calls" a RPM limiter switch". I don't know where this is or if it part of the 911 sc.

If anyone has any additional ideas I would appreciate comments, as I am about to lose the remaining hair I have over this one. Thanks
Chuck

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, best of luck:)
andy

Are you getting spark at the plugs? Have you checked the coil?

Fuel pump relay?

Check the system pressure, if there is none then it is your fuel pump. Then check the fuel pump and or relay. If you can give it 12V at the pump and it pumps up to fuel pressure then it is the relay.

I have checked the spark by pulling the #4 plug out and attaching a ground to it while cranking the engine. I got a strong spark. I have also swapped relays with three new ones I have ,and no change. As for the rain, here in Fort Myers it has been dry for about a month, so I am sure it has not seen any moisture. The only thing I have not checked yet is the system pressure, which I will do today if possible.
Thanks guys for the responses, and I will follow up with any future success's or failures as I go along.
Chuck

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.

Is your interior light working? Is the frequency valve buzzing with the ignition on? Check the relays under the passenger seat. If you are sure you are getting fuel (lift up the plate inside the air box and maybe pull an injector) and spark, then I would suspect some kind of electrical problem in the fuel injection system.