911 with no start, need help.

[radobard]

I have a 1974 porsche 911 targa with a 1979 3.0 sc motor in it. I am having problems with starting the engine. The engine will turn and occasionally start for 2 to 5 seconds. I have replaced the fuel pump and the ignition system seems to be working. I noticed that the tachometer is the original 1974 tach that came with the car. Should I have a 1979 tach in there since I have the 3.0 engine? Would this be the cause of the no start?

Roland
Old Yesterday, 05:43 PM

[Flat6pac]

The tach runs off the CD box. 3.0 tach drive goes through the 14 prong connector. You had to pull the purple/black stripe wire out of the connector and jump it to the white T connector on the longitudinal under the CD box. take the tach out of the system by unplugging the tach wire until youre running.
with the key on, the fuel pump should be running because 74 didn't have the sensor plate pump shutdown that the 3.0 has
will you start by lifting the air flow sensor and permitting fuel flow in injectors? Can you keep it running by slightly lifting the airflow sensor with someone turning the key to start?
3 things to run fuel, spark, and compression
Bruce

[radobard]

Bruce,

Thanks for your reply and suggestions. I am a novice when it comes to porsche engines and the terminology you used in your reply. I will find someone to explain to me what you have said. If you could send me some photos of what you were talking about it would help me greatly. If it matters any, I have a permatune ignition box in the car.


Roland

[fintstone]

No. You can use your original tach.

[Flat6pac]

I was telling you how to take the tach out of the system.
14 prong connector is pictured as is the white T coming off the engine
To drive the tach, you need to jump the tach wire from 14 prong connector to the white T under the CD box.
The airflow sensor is inside behind the air filter, kinda looks like a horse shoe. with the key on, lift and you ll feel the injectors flow fuel and pressure back to your hand. 5 seconds of lift is all you need.
there should be fuel to start. If you lift slightly while starting you ll be squirting fuel to run with.
Bruce
14prong connector left rear corner of the engine compartment


Typical Tconnector I mentioned

[radobard]

Thanks, Bruce.

[boyt911sc]

Originally Posted by radobard

Bruce,

Thanks for your reply and suggestions. I am a novice when it comes to porsche engines and the terminology you used in your reply. I will find someone to explain to me what you have said. If you could send me some photos of what you were talking about it would help me greatly. If it matters any, I have a permatune ignition box in the car.


Roland

Roland,

Check your ignition sparks. Permatune is notorious for failure.

Tony

[patz]

CIS is all about fuel pressure. You will need gauges and an exhaust anylzer. Suggest picking up a Bentley manual and doing a search.

Permatunes, suck at best.