930 Starts but wn't keep running

John McMahan · 11-03-2011, 03:00 PM

I am working on a 1982 930 that was parked for years. It now has a new battery, rebuilt alt, The CDI was checked hot and cold with no problems, new coil. The car starts but will not continue running.
I replaced the ignition switch but to no avail.
I replaced the fuel pump, fuel filter and both fuel pump relays and they are both getting juice from #30 and #87, yes I can hear the pump running. I even replaced the red relay in the rear and it's working.
I have attached a photo of what appears to be a pressure regulator and three solenoids/valves mounted in front of the car, they appear to be fuel related but I see no fuel in or gong thru them.
What do these valves do?
After looking at this forum It appears that every Porsche expert is on this site, so any help or suggestions will be greatly appreciated.

masterdave · masterdave's Garage

check, the spark plugs, wires, distributor (I think it has one) rotor. ECU/injectors (I think it has them). Did you check the timing. Things may fall out of place over time.check the Chain tensioners. are your turbo waste gates functioning properly, if they are stuck shut you may be building up pressure and causing the engine to cut its self out as a result. Check or replace the air filter if its dirty. If you have not yet, i would change the oil in the car as well as all other fluids, if the car has been sitting for a while the fluids can settle and get funky.

Regards
dave

willtel · 03:20 PM

Welcome.

Check for a massive vacuum leak that would prevent the metering plate from being drawn down and delivering fuel. The rubber elbow on the left of the engine bay is sometimes the culprit.

If it is an air leak you should be able to keep the engine running (roughly) by having someone push down on the metering plate as you fire it up.

Also check here, http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/547032-sticky-common-answers-why-my-car-doesnt-start.html

And look in the 930 specific forum here, 911 / 930 Turbo & Super Charging Forum - Pelican Parts Technical BBS

I have no idea what those valves are but they are not factory. They almost look pneumatic. Is this an old race car that may have had air jacks?

LuftWaffle · 11-03-2011, 03:18 PM

First off, welcome to the board.

Whatever all of that is - it's certainly not stock. Do you think they may be fuel pumps? Which pump did you replace? The stock configuration is two pumps in series with one being under/behind the tank and one in the rear on the left side of the bulkhead. Have you traced all the fuel lines? Is the induction system the stock CIS? Checked for fuel at the injectors? There may have been many things changed on that car that you'll need to sleuth out. -John

John McMahan · 11-03-2011, 03:21 PM

Thanks for the reply, I've changed the oil, filter and fuel. I have the air filter off.
It starts up easily so the wires, cap, rotor should be ok. I think I am starting on the cold start solenoid but not getting fuel or spark after that, and with the CDI I can't check for power on the pos side of the coil.

John McMahan · 11-03-2011, 03:28 PM

thanks for the replies. I replaced the fuel pump under the tank and filter in eng. compartment.
The metering plate appears to be stuck I can't push it down. i had forgot about the metering plate. If I'm getting fuel to the cold start I would assume that the fuel system is flowing correctly. It appears to be all stock

LuftWaffle · 11-03-2011, 03:33 PM

There are a couple of possibilities for not being able to push down the metering plate. The fuel head may be all gummed up and/or rusted (most likely) or the control pressure is so high that you can't move it.

John McMahan · 11-03-2011, 03:37 PM

When you refer to fuel head are you referencing the fuel distributor on top of the engine?

John McMahan · 11-03-2011, 03:41 PM

I'll take all the lines loose tomorrow and check the pressure to the fuel dist and try to free the metering plate.
Thanks for the suggestion

LuftWaffle · 11-03-2011, 03:42 PM

Yes. There is a plunger in the center of the fuel distributor that moves up and down in a bore in relation to the movement of the metering plate.

Quote:

Originally Posted by John McMahan

When you refer to fuel head are you referencing the fuel distributor on top of the engine?

LuftWaffle · 11-03-2011, 03:46 PM

I think it would be wise to get a set of CIS test gauges and test the system and cold/warm pressures. Not only will that help troubleshoot your immediate problem, it will help to determine the overall running characteristics.

Quote:

Originally Posted by John McMahan

I'll take all the lines loose tomorrow and check the pressure to the fuel dist and try to free the metering plate.
Thanks for the suggestion

John McMahan · 11-03-2011, 03:54 PM

Luftwaffle, thanks for the ideas, I bet thats going to be the problem, I got a 400i ferrari out of Colorado 15 years ago and the additives in the fuel gummed up that fuel distributor bad, and I had forgotten until you mentioned it. I will check it out in the AM

LuftWaffle · 11-03-2011, 04:08 PM

Good luck and keep us posted! If it does end up being all gummed up it's probably safe to assume that other fuel system components are in the same condition. Like Wiltel mentioned above, there is a separate 930 board that a lot of the 930 guys hang out. Lots of 930 "braintrust" there!

willtel · 11-03-2011, 04:30 PM

The metering plate is a pretty good sized lever so be gentle with it. If the plunger is stuck you don't want to gall the surface it slides on.

smurfbus · 11-03-2011, 11:01 PM

The start comes from the cold_start_injector I believe. I had my car shipped and it would not run after that 2 months. I finally used plenty of starthelper on TB and it got it running after couple of attempts. You need to remove the IC to get to the TB though.

If it was parked for years the fuel head might be gunked though.

jeffs9146 · 11-04-2011, 05:37 AM

Quote:

Originally Posted by willtel

Welcome.

Check for a massive vacuum leak that would prevent the metering plate from being drawn down and delivering fuel. The rubber elbow on the left of the engine bay is sometimes the culprit.

If it is an air leak you should be able to keep the engine running (roughly) by having someone push down on the metering plate as you fire it up.

Also check here, http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/547032-sticky-common-answers-why-my-car-doesnt-start.html

And look in the 930 specific forum here, 911 / 930 Turbo & Super Charging Forum - Pelican Parts Technical BBS

I have no idea what those valves are but they are not factory. They almost look pneumatic. Is this an old race car that may have had air jacks?

I agree with the above vacume leak!!!!!

I just went through this with my '83 SC and it took forever to get all of the small vacume leaks sealed enough for the plate be lifted enough for a consistant idol!

Use some carb cleaner and with the car started (somone else turn the key) spray it at the intake connections around the AAR, WAR and all vacume line connections except the ones at the dizy (could ignite)!

I drove my car yesterday for the first time in a long time once the vacume leaks were repaired!!