Porsche 928 S 1982 euro spec runs for few seconds and stops

[swordfish767]

Hi, I am new here...Recently bought Porsche 928 S 1982 euro-I am in Europe.
Cleaned the tank, bought new pump, filter, cleaned the CIS and all filters in CIS and WUR, cleaned the injectors. The car started from the first try, but works very unstable, just for few seconds and dies.When is off the fuel accumulator squirts fuel. I know probably will new new accumulator, but what is the reason for the short run?
Thank you in advance.

[MPDano]

Your running off the cold start valve only. Pull one of the lines to the injector and start the car and see if you get fuel would my first step. Use an old plastic soda bottle to catch fuel. also, pull your plugs and see if they are dry.

[uBoat Commander]

I have the same issue on my 81 928S with CIS - would love to know your answer when you get it.

[GuyS]

I have bought both a CIS and LH jet car out of long term hibernation. The CIS car required everything to be cleaned, rebuilt or replaced. Varnish, gum and debris are a mortal enemy for these cars. I would not shortcut. Drain and clean tank well. Clean pumps. Replace filter and in this case accumulator. Blow out fuel lines with compressed air. Removed and clean FD (without tearing into it)
Remove and clean WUR. Add Berryman to tank before running again.

I kept trying to shortcut. In the end it was fun but a a waste of time. My car runs like a dream now (with one small exception) but it required all of the above. Good luck

[swordfish767]

Hi, thank you for your replies.
I have cleaned everything, including CIS + new seals.
I did try to test the hard lines and there is fuel to the injectors....
Dont know what else to try...
The fuel distributor is completely clean and with new seals.
Any idea?

[MPDano]

Plugs wet or dry?

[curtisr]

I assume that the vehicle wasn't running when you took possession. Did the previous owner tell you why or what he/she had done/did not do?

I had a similar issue and I 'solved' it by swapping out the fuel injection relay for an OEM. The position (XI?) had a generic relay in its place. Of course, what ever you have in place may be faulty or the connection needs cleaning.

As Leo asked, dry plugs might point you in this direction.

[gbgastowers]

I assume that the vehicle wasn't running when you took possession. Did the previous owner tell you why or what he/she had done/did not do?



I had a similar issue and I 'solved' it by swapping out the fuel injection relay for an OEM. The position (XI?) had a generic relay in its place. Of course, what ever you have in place may be faulty or the connection needs cleaning.



As Leo asked, dry plugs might point you in this direction.

With early cis I don't think he has a fuel injection relay. He just has a fuel pump relay

[MPDano]

Originally Posted by gbgastowers

With early cis I don't think he has a fuel injection relay. He just has a fuel pump relay

Correcto

[lowpassat]

Jump your fuel pump relay (pins 30 and 87) and lift the plate on the fuel distributor, if you don't have fuel flow to the injectors after that then you probably have a gummed up plunger in the distributer.
Make sure you are getting fuel to the distributer. CIS is all about fuel pressure, its really hard to diag CIS without a good fuel pressure gauge..
If lifting the plate with the relay jumped doesn't get fuel to your injectors I would start looking for a distributor from a running car to swap in.

[gbgastowers]

Push plate down on 928 for fuel. Lifts on 911

[lowpassat]

Originally Posted by gbgastowers

Push plate down on 928 for fuel. Lifts on 911

I did not know this! I'm used to VW/Audi CIS cars.

[swordfish767]

The car is 82 year and its mechanical injection, so there is no relay for the injectors.
I bought it as a non runner.The owner said it has blocked injectors.
The tanks was full of rust with blocked filter, the fuel pump was gone, the fuel lines were clogged by rust and varnish, all 8 filters on top of fuel distributor were blocked, the filter of the main barel of the FD was completely blocked, intake filter blocked, plunger stuck, WUR filter blocked, and blocked injectors.
I cleaned all the components and decided to start it.It started from the first time, but just for few seconds........
When the pumps realy is jumped and when the plate is pressed down the fuel squirts from the injector lines.
As I said the fuel distributor is rebuilt and cleaned.
I noticed that the air plate is completely closed before the engine starts-is it normal?
Have not checked the plugs yet, because dont have the correct tool.
I hope I can check them tomorrow and will let you know.
What is your opinion about the fuel accumulator?
Its a bit strange that it has 3 intakes-2 on the bottom and one on top.
The top one is open and not attached to any pipe-is it normal?
I did check it by blowing air from the both lines...and it blows freely.
I guess it should take a pressure at least 3bar...

[gbgastowers]

Don't know much about the accumulator cause I never touched mine. The plate stays closed unless it pulls in air or you push it down. Don't delay getting the gauges for pressure tests. Otherwise your chasing your tail. I bet I read and studied diagrams on how that cis with wur works one hundred times and i still have trouble getting it straight in my mind

[Danglerb]

Everything needs to be right to run with CI$

Since it starts on the cold start, compression, spark, and fuel are OK then, since it dies something is wrong in the running portion of the fuel system.
Vacuum control lines need to be routed correctly with no leaks.
Fuel regulators and accumulators need to work without leaks (not dripping leaks, but leaks through the diaphragm to the vacuum lines).
WUR, warm up regulator needs to work.
Fuel distributor needs to work.
Injectors need to work.

Gauge set for CI$ is essential to check that stuff.

[swordfish767]

I guess some of the injectors are not working properly
I did try to fill them with some carb cleaner and 2 of the injectors did not hold the liquid-so they are completely open and not working properly.
At what pressure they should open?

[curtisr]

Originally Posted by MPDano

Correcto

I sit corrected. And have learned much more about K versus L Jetronics. Curious, my '82 requires just such a relay as did some other '80-'84s.

Does anyone know what determined whether a model came with CIS versus the L-Jetronic? Both were available in North America.

[MPDano]

Here you go Curtis:

Porsche 928 Forums dot com - View topic - 928 Engine Types & Performance Data

[curtisr]

Originally Posted by MPDano

Here you go Curtis:

Porsche 928 Forums dot com - View topic - 928 Engine Types & Performance Data

Thank you, Leo. I followed the link and have yet again learned lots. Where do you get all of that information?! My Porsche Buyer's Guide book is not that detailed (sadly)!

[Luis_M]

Originally Posted by swordfish767

What is your opinion about the fuel accumulator?
Its a bit strange that it has 3 intakes-2 on the bottom and one on top.
The top one is open and not attached to any pipe-is it normal?
I did check it by blowing air from the both lines...and it blows freely.
I guess it should take a pressure at least 3bar...

The top port is present on some versions of the accumulator as a return to the fuel tank. Others just have a small screw there without a port (like attach pic) as this is on the non-fuel side of the internal diaphragm. If there is fuel at the port/screw, the accumulator is leaking and should be replaced. The accumulator is exposed to full system pressure (5 bar) and probably also dampens pulsation effects from the pump.