78 SC startinh problem
 

Well after the rebuild the car started just fine. Ran it for a few days and it started just fine. When I put my hand on the fuel pump it feels like it first runs then comes to a complete stop.ALSO REPLACED THE FUEL FILTER. i CAN SHOOT STARTING Fluid IN THE INTAKE AND IT WILL RUN.It was sitting running at idle and it just stopped and will not restart. Checked the coil still no go. Is the pump supposed to stop or should it keep pumping the extra gas back to the tank. The fuel pump is new.

Do you still have CIS ? When you first study the fuel pump circuit in the wiring diagram, it will give you a headache. The FP is powered when the key is in the start position by one circuit, once the engine fires and is creating vacuum, a second ciruit powers the FP. When the engine dies the air flow sensor plate drops and disconects power to the FP for safety reasons. Try this test, remove the air filter, turn the key to ON, push up on the air flow sensor plate while listening for the pump (only for 2-3 seconds). If you do not hear the FP, check that the switch is plugged in behind the FD. Then start testing the circuit at the FP.

when you do as paul said, you will hear a loud whine or squeal coming from the injectors if the pump is running. this is spraying raw fuel into the engine, so do not do it too long.

if this is good, pull a plug wire and connect a sparkplug to it and check for spark.

1978 911 SC
Found out the problem after replacing the fuel pump with a new one. Got her started again.
Someone had butchered the wiring harness and added an aftermarket fuel pump relay.
It’s only working some of the time but not all of the time. This small black relay has no name
on it. Only the NBR: C9406 it is five spade – 30 – 85 – 86 – 87 and 87a. Eventually I want to
go back to the stock one when I find someone parting out a 78 911 SC.
In the mean time I would like to get a replacement rely for the C9406 so I can move the vehicle around.
Any ideas where I might find one or somehow identify who makes this one and what German vehicles it fits?
I tried the local auto parts store and had no luck.

Thanks in advance.


K.T.
1973 911 E 2.4 MFI
1983 911 SC
1978 911 SC
1965 Devin "D" / 1967 912 Power Plant
YOUR CLASSIC RIDE – KCMO CAR CLUB - MEMBER
1998 GMC Serra 4X4 Z71
John Deere LT166
Money Can Buy Happiness........Buy A Porsche......a

I see you have a '83 SC.
Go under the passenger seat and carefully pull out the relay for the Lambda brain.

It might have the right pin configuration and rating.
These are Bosch relays and for the pump you may want a 25 or 30A rating; a VW dealer might sell these.
Let me know if that works out.

Thanks Dr. Gunter. will check when snow storm lets up.

K.T.
1973 911 E 2.4 MFI
1983 911 SC
1978 911 SC
1965 Devin "D" / 1967 912 Power Plant
YOUR CLASSIC RIDE – KCMO CAR CLUB - MEMBER
1998 GMC Serra 4X4 Z71
John Deere LT166
Money Can Buy Happiness........Buy A Porsche......a