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

Clear shot.........
 

jrnicl3,

It's difficult to see clearly what the 'cut' really looks like. Is the hose cut and leaking fuel? It looks like the outer cover of the hose is spliced open. Got another shot of the hose (with a better focused shot)? Thanks.

Tony

I bet this is the part. I am not sure what you call that fitting (barb?) but I don't think the end shown as the "cut" is cut. Find the hose downstream of this connector and post a pic. It is the main artery feeding the fuel distributor.

Edit - Cripes - now I see the cut/split hose in your pic - I was focused on the male end fitting.

Sorry - here is the pic

http://forums.pelicanparts.com/uploa...1319684188.jpg

The hose is not cut. Its only the protective rubber sheath. Its a non issue and you can peal the sheath off if you like.

It do need to be connected to the line to the engine though.

What make and type did you get? Bosch? Pierburg? With internal or external check valve?

Please, a more precise description of your procedure for trouble-shooting would make it easier to help you.

Will you get the Bentley? :cool:

It is possible that the control pressure is way out but that won't happen all by itself from sitting in a barn for 4 years.

The fact that the car starts when given quickstart means it has spark and the plug wires are in correctly etc.

Sounds to me like the fuel doesn't reach the injectors. Bridge terminals 87a and 30 on the fuel pump relay and when you turn the ignition on the fuel pump will start pumping. If you don't hear that, your fuel pump is not pumping fuel.
If you hear it working, do what they guys said above. Lift up the fuel flap inside the air box and hear whether the injectors start singing.

Wrong terminals (typo??).............
 

Patronus,

The terminals should be 87a & 30 to do the test you suggested. Not 87 & 30, otherwise the starter will run even with the engine running and could result to catastrophe. HTH.

Tony

Tony, you're right. Thanks for pointing it out. Fixed it in my post.

Innocent mistake.........
 

Patronus,

We all make mistakes and learn from each other's thoughts. BTW, I'm about to make a post to correct a major mistake I believe was correct and strongly believed that I was correct until I made an investigation to make my point. It turned out that I was incorrect in my assumptions. To commit a blunder and admit it, is a virtue. Refusal to accept your mistake is outrageous. Please continue to participate and share your knowledge with us. Thanks.

Tony

The jumper-the-relay procedure means to jumper the relay sockets and not the relay itself.

Tony and I went through this a month or so back. He did not pound on me too hard, but hard enough that I will never forget that piece of info. :-)

The procedure according to the factory workshop manual is actually to take an old relay and bridge terminals 87a and 30 inside the relay. Hence my wording. However bridging the sockets is easy so that is what I also do.

I will check my factory manuals as I remember seeing that. Must be something I am doing in practice that deviates from the correct procedure.

Here it is - loud and proud. Trust me, on an 1980 and 1981, doing this turns the starter. There must be some differences in circuitry.

Step 5 says to turn the key to on.

http://forums.pelicanparts.com/uploa...1319766921.jpg

where is terminal 87a and 30?

ok - do the bridging of the sockets with a wire, please (until we figure out why the SC's act different than 2.7's using this procedure)

Go to the relay closest to the driver on the battery side of the front luggage compartment. It is probably red.

Pull the relay out (it can only go back in one way) and put on your reading glasses and look at the pin side of the relay. See the terminal numbers? See 87a and 30? Match the pins to the sockets - more than once to be sure - and place (stuff the bare copper ends) a wire between both sockets. Take your car out of gear (heh heh) and turn the ignition key to on.

The fuel pump will run.

On the SCs I have owned and worked on the fuel pump relay (red) is in the front trunk, all the way to the back. the turbo uses two black ones in the front trunk, and a red one in engine compartment (total of three).

Hey James - see my post 31 (and feedback) . The factory says to jumper the relay pins on the FP relay (for a 76) but if you do that to an 80 it turns the starter. It is an anomaly that I have not figured out. That's what the factory manual pics are for.

I do have a question for you - off topic and not critical - my pal has an 89 930 - all of his relays are red - a whole row of round red relays in the luggage compartment - where my 81 only has the FP relay being red. Any idea as to why?

First you should be able to hear your fuel pump running, and you should be getting fuel to the engine! If not deal with that first! Then move on to the vacume leaks!

I have an '83 SC motor that I have been working on bringing back after 14 years of sitting on a palet!

The number one problem I have run into is "VACUME" leaks! I am now at the point that the car will run and idol but still has vacume leaks. If I spray carb cleaner or either it will run great but if I don't it trys to find idol and hunts around! I still have a leak but it now runs and sounds great, everything I have done so far has progressed to the positive which was vacume leak related!!

Have you done this test?
 

Patronus,

If you use an old working relay and bridged terminals 87a & 30, turning the ignition switch ON position would result to STARTER cranking!!!!!! What you need is an old non-working FP relay to make it work. Why? Here is the reason:

Terminals 87a-30 are NC (normally closed) terminals.
Terminals 87-30 are NO (normally open) terminals.

When your turn the ignition switch to ON position (not start), power is sent to terminal 87a and 86 (bridged at the socket side). The coil would be energized if 85 is grounded. Thus the normally closed terminals would open and the NO (normally open) terminals would close: 87-30

If you bridge terminals 87a & 30................terminal 30 is already connected to 87 after you turned the ignition switch. This is how the power is transmitted: 87a-------30------87 (ignition switch @ ON, 87a & 30 bridged).

BTW, '76-'83 have basically the same wiring configuration except for very minor difference but not in the FP circuit. For the sake of demonstration, try it on your car and keep us posted.

Tony