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turts924
Joined: 12 Apr 2010
Posts: 14
Location: Madison, Ohio
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 Posted: Sat Jun 11, 2011 10:28 pm Post subject: Young noob needs help with 924 NA |
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Hello all,
I have a '79 924 NA with a strange problem. I searched and could not find any answers. Here's the problem:
The car would not start so I removed the plugs and found them to be fusl soaked. I removed the injectors, jumpered the fuel pumps. I found that I have no control over the fuel pressure. I tried adjusting the fuel dist. screw all the way in and out, but the same amount of fuel came out of the injectors. I also found that the injectors are firing after the ignition switch goes from start to run.
The injectors, fuel pumps, and filter are new.
My Uncle and I have been working on this car for a while trying to get it ready for when I get my license, but we are about to give up and scrap the whole project.
Please help.
Thank you!
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dpw928
Joined: 02 Nov 2002
Posts: 1860
Location: owasso, ok 74055
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| Posted: Sun Jun 12, 2011 12:11 am Post subject: |
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The Continuous Injection System (CIS) is made to run continuously if the air sensor plate is opened by air movement. It appears the car has set for a long time. Old fuel can really plug up this system. Try removing all the tubing connection and spraying throttle body cleaner into all the ports. Also remove and clean the relief valve and ports on the side of the fuel distributor. There are often wiremesh filters on the inlet to the fuel distributor and control pressure regulator (WUR) that could be plugged and causing problems. The piston in the fuel distributor could also be stuck in a high position.
As a minimum you should have a copy of the Haynes manual. It gives a good overview and spec's for the 924 CIS system.
Dennis
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81 931 5 sp
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Harm
Joined: 02 Apr 2009
Posts: 1378
Location: Holland
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| Posted: Sun Jun 12, 2011 1:30 am Post subject: Re: Young noob needs help with 924 NA |
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+ on the Haynes…
You could do a search inhere for links to d/l the Bosch K-jet manual or read
http://www.diagnostic-assistance.co.uk/mech_inj.htm
| turts924 wrote: | | … I found that I have no control over the fuel pressure |
See to it your Primary Pressure Regulator on the side of the Fuel distributor is complete and functional.
| turts924 wrote: | | … I tried adjusting the fuel dist. screw all the way in and out, but the same amount of fuel came out of the injectors. |
That would indicate the Control Plunger is in the up position leaving it unable to respond to the air flap.
Three screws hold the Fuel distributor to the airmeter. Take them out and pull the Fuel distributor
from the airmeter so you can reach the darn plunger underneath/inside and set it free.
| turts924 wrote: | … but we are about to give up and scrap the whole project.
Please help.
Thank you! |
No need to threaten us   |
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turts924
Joined: 12 Apr 2010
Posts: 14
Location: Madison, Ohio
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| Posted: Sun Jun 12, 2011 2:49 am Post subject: |
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Thanks for the info! I will try every suggestion. I do have the Hayne's manual and have found it pretty informative.
Is it normal for the injectors to fire after the ignition is in the start position? Does this not spray fuel into the cylinder after ignition, and in-turn wash down the cylinder and end up in the oil?
Thank you all again.
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Harm
Joined: 02 Apr 2009
Posts: 1378
Location: Holland
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| Posted: Sun Jun 12, 2011 4:40 am Post subject: Re: Young noob needs help with 924 NA |
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| turts924 wrote: | …jumpered the fuel pumps.
…
… I also found that the injectors are firing after the ignition switch goes from start to run. |
One thing at a time please
If I were you I'd be more worried about the WUR and fuel pressure.
I can't be sure on that one since my car is no US '78 and there are differences between these models.
One of the differences is the electric air flow sensor plugged onto the airmeter.
When the running engine is not lifting the round air sensor plate (suction, under normal
circumstances) it wil kill the fuel delivery. It detects the engine isn't running so to speak
and is there for your safety so you won't end up in a ball of fire.
Secondly, on the later models for sure, as long as there is no rev signal from the electronic distributor
indicating the engine is running or turned over, the fuel pump will stall. The pump will only run at the
very beginning before/in the starting proces for a few seconds to build up the fuel pressure.
At least in my case, the '82 toofah. It is controlled by a time mechanism inside the fuel pump relay.
If I'm correct your car uses an earlier fuel pump relay. The one that carries a fuse on it.
I suggest someone else up here looks into that.
| turts924 wrote: | | Does this not spray fuel into the cylinder after ignition, and in-turn wash down the cylinder and end up in the oil? |
Yes.
But you don't want fuel in fresh new oil, so stick with this until you get her running.
Be kind to the cam, don't rev too much, and replace the oil before you go for a spin.
Cheerio.
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Porsche 924 NA 1982 LY7A/A3A3 _ Greater driving pleasure never harmed anyone. |
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Harm
Joined: 02 Apr 2009
Posts: 1378
Location: Holland
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| Posted: Mon Jul 11, 2011 6:52 am Post subject: Re: Young noob needs help with 924 NA |
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| turts924 wrote: | Hi all,
First off, thank you for your continued support.
I have had a "no start" situation for months now and I am really about to quit. I keep saying this, and interestingly enough, I keep at it. Insanity must be in my blood 
I have one question to ask: How is it possible to have no control over the fuel pressure? Specifically, I am attempting to set the CIS mixture and I have discovered that no matter how many turns in or out I go with the 3mm set screw, the fuel pressure/volume out of the injectors is the same.
Am I missing something?
This all ties into my main theory that I am getting too much fuel into the cylinders and it continues to saturate the plugs.
Again, what am I missing?
My uncle had been helping me in the past, but he is so busy these days that I am on my own now and I am flailing. Please help.
Thanks! |
What is the status on the Control Plunger?
Kind regards, Harm.
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Porsche 924 NA 1982 LY7A/A3A3 _ Greater driving pleasure never harmed anyone. |
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Harm
Joined: 02 Apr 2009
Posts: 1378
Location: Holland
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| Posted: Tue Jul 12, 2011 7:24 am Post subject: Re: Young noob needs help with 924 NA |
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| Harm wrote: | | See to it your Primary Pressure Regulator on the side of the Fuel distributor is complete and functional. |
Make sure your Fuel return line isn't clogged. |
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turts924
Joined: 12 Apr 2010
Posts: 14
Location: Madison, Ohio
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| Posted: Tue Jul 12, 2011 8:57 am Post subject: |
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Thanks Harm, I will check it and let you know.
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MRPETE
Joined: 07 Nov 2010
Posts: 67
Location: CALGARY AB CANADA
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| Posted: Tue Jul 12, 2011 3:45 pm Post subject: |
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Try loosening one injector fuel line.Have a bud crank the engine if it starts cool see if fuel is still coming out when it stalls.CAREFUL raw gas!I had trouble with my CIS unit because it would stick, sometimes too much fuel sometimes none this as said before by the WUR A little residual crap can can set you back to ground zero....Expect the unexpected.If the O rings are not
Perfect (close but no cigar)it will give ya' grief!
This is only an add on to what good advice the other bro's have given' you
Good Luck
Pete
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tc357max
Joined: 05 Jul 2011
Posts: 2
Location: Harrisonburg, Va
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| Posted: Wed Jul 13, 2011 12:48 pm Post subject: fuel dist. |
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I just got my 77 924 going had the same problem. Fuel distributor problem. My would dump to much fuel at start up. Take distrib off and pull out center shaft/plunged. It should move smooth and be crud free. If that is fine, the distribution will have to be replaced or taken apart. Remove nut and washer at center then remove all bottom screws. Then separate two halves. Watch under the shin are springs and disks. With both halves apart pull out center distinctions shaft. Then check and replace all orings.
Mine had split orings. |
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MRPETE
Joined: 07 Nov 2010
Posts: 67
Location: CALGARY AB CANADA
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| Posted: Wed Jul 13, 2011 5:19 pm Post subject: |
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DO NOT use anything more abrasive than a soft brush to clean any part of this or yer probably hooped
DANGER WILL SMITH DANGER
Pete
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turts924
Joined: 12 Apr 2010
Posts: 14
Location: Madison, Ohio
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| Posted: Wed Jul 13, 2011 6:21 pm Post subject: |
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Thanks guys! I will attempt to get my Uncle to help with the dismantling. I am learning a lot, but this may require more skill than I have.
I blew out the return line and unfortunately, no blockage.
Thank you all for the help! I hope this is the answer I've been looking for.
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turts924
Joined: 12 Apr 2010
Posts: 14
Location: Madison, Ohio
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| Posted: Thu Jul 14, 2011 7:36 am Post subject: |
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Thanks to you guys, I may have fround the problem. We took the fuel dizzy apart this afternoon and found 3 of the 4 o-rings torn and the other disintegrated when removed. Now all I need are the sizes of the o-rings. The four small and one larger one? Anyone know the actual number of them or is it a trial and error job?
I can't wait to get her back together and start her up!
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MRPETE
Joined: 07 Nov 2010
Posts: 67
Location: CALGARY AB CANADA
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| Posted: Fri Jul 15, 2011 3:19 pm Post subject: |
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Do not screw with close Do research and buy a KIT IDEOLA is very knowledgeable I would try him first Good luck.You have one chance
to get it right the first time
Pete
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'77 924
"81 924
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Joes924Racer
Joined: 03 Nov 2002
Posts: 11964
Location: Oregon, Denver Colorado native!
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| Posted: Sat Jul 16, 2011 2:15 am Post subject: |
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Youll also need to know how many turns the dizzy afm screw needs to start or go rich..Fuel dizzys hard to come bvy in your neck of the words
Im sure theres a cross ref. around that showd what other car makes will work. Good luck getting it together I only say that because Oh ive been there done that to my dizzy and found the screws holding it together to be quite stubborn...
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
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