Engine Start issue...
 

Hi,

I bought a 1979 911sc a week ago and the last time the previous owner drove the car was 4 years ago. Otherwise it sat in his barn.
I am trying to start the car with no result. I did flush the oil, replace the fuel filter, the fuel pump. The car does crank but will not start. When I spray fluid, and start the car, it runs for a few seconds and stops. Any ideas about what to do next?

Thanks

Fuel pressure is out of spec. Get the Bentley manual and fuel pressure gauges.

What do you mean by out of spec? And What will the fuel pressure gauges do? Help!! I am new to it.

I'm Learning. Thanks!

First, welcome to the forumSmileWavy!

Second, you will need to do a little basic reading about your CIS fuel injection system. I suggest you do a quick reading on the following site: CIS Primer for the Porsche 911.

To get you going however (no pun intended), you can try the following technique. Since it sounds like your car is not getting fuel and it has been sitting for four years, try to pressurize the system first. To do this, remove the air filter from the engine and you will see a metal "plunger" inside the intake. Turn on the ignition, go to the engine compartment and gently push up on the plunger. Doing so should cause the fuel pump to run and pressurize the fuel system. Hold the plunger up until you hear a "squeal" from the injectors--that's the sound of fuel being sprayed into the intake ports. As soon as you hear the squeal, let go of the plunger as you could flood the car, or worse. Now, the system is pressurized and fuel is reaching the cylinders. Try to start the car and report what happens.

The gauge set referred to is a pressure gauge with a "T" connector and valve that is used to diagnose CIS systems. You will need one.

In short, there are many reasons for your situation, but since the car fires with an injection of fluid, it does have spark and compression. Try the above test and report back what happens, and read the Primer.

Did you drain the old fuel and fill the tank with new stuff?
Since it runs a little with stater fluid ignition sounds alright.

Since you replaced the pump and filter, there may be air in the system.

Try this:
Remove the air filter and cover,
Turn ignition ON, (Not crank!),
Reach into the airbox and carefully lift the air sensor plate for 3-5 seconds only to get the air out.
The injectors should hiss and squeal indicating that fuel is delivered.
Try starting.
As soon as you can, use 2 cans of Techron in a full tank and run it through the system to unclog FD and injectors.

Sensor plate and /or plugunger not moving freely

Auxiliary air valve does not open

Electric fuel pump not operating

Cold start system defective

Thermo-time switch defective

"Cold" control pressure outside tolerance

Injector leaking, opening pressure too low

Injected fuel quantities unequal

Basic idle setting incorrect

This is not CIS troubleshooting.........
 

This not the way to find the problem/s!!!! You just recited a litany of probable culprits. I'm glad you are not my mechanic because it would be a very expensive bill by the time I get my car back. You could still add some more like:

vacuum/air leak
air mixture
ignition timing
cam timing
ignition switch
CDI

So what's your point? Check everything you mentioned above? Could you elaborate more so we could follow the logic? BTW, you missed the fuel accumulator.

Tony

OK, I did what you suggested and it does the same. So, am I able to use bosh platinum spark plugs?

/


I assume I should also replace the spark plugs?

Yes, replace the plugs with cheap-o copper plugs. NGK works fine. Factory gap.

CIS works on vacuum and pressure. There is no mass air flow sensor - it's old, old, old. However, Ferrari used it in the 512 BB so it ain't that bad. Seriously, it was state of the art in the early eighties.

The fuel pressure gauge will tell you system pressure (core pressure), cold and warm control pressure as well as residual pressure.

The system does not allow the fuel pump to dictate the fuel pressure at the injectors. The fuel pump MUST deliver at a subscribed rate but there are other goodies that throttle the 70-ish psi system pressure to a operation-friendly lower psi at the injectors. Straight system pressure would piss so much fuel through the injectors the car would choke and die from being too rich.

This is where the fuel regulator enters. It takes the system pressure and throttles it back, based on how cold or warm the engine is, and feeds the injectors the pressure - called control pressure - that they need to feed the engine the right amount of fuel.

The gauges tell you what the fuel regulator is doing.

Are you saying that the injectors squealed for about 5 seconds but after this procedure the engine didn't start? Not even some sputtering?

Correct Bosch or NGK COPPER plugs for '79 SC.

The engine started for couple seconds(4seconds)after spraying starter fluid

Car sat in Barn for 4 years? Take the exhaust off and clean out the mouse nests?

Did you follow the procedure suggested to check that fuel is coming out of the injectors? :confused:

Remove airfilter, ignition ON, lift airflow sensor plate, injectors squealed???????

I did what you said as followed and I could not hear any hiss and squeal:
I found out that the fuel line next to the fuel pump is cut. That is probably the reason that the fuel never reached the injector. Even if I turn the ignition, no gas is coming through the line.

So how to test if the fuel pump is really operating properly. I did replace the pump with a new one.

Quote: "I found out that the fuel line next to the fuel pump is cut." ???

Cut meaning exactly what?
Open line?
Leaking fuel?

Which side of the pump?
Intake?
Outlet?

Did you replace the line?

You need to get the Bentley SC Repair Manual which is the Bible for SC owners. It explains many issues with pictures, it's a must have.

It shows how to jumper the fuel pump relay to hear the pump run.

Wonder if the line was cut to drain the fuel? Is it before or after the FP? Assuming cut means exactly that, the line is cut in half.

Here is a picture I took to explain what I meant by "cut".

http://www.flickr.com/photos/69127554@N06/6284368333/

Here is a picture I took to explain what I meant by "cut".
http://forums.pelicanparts.com/uploa...1319676635.jpg