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78 924 I need to get running

 
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78kate  



Joined: 11 May 2018
Posts: 3
Location: Orangevale CA

PostPosted: Fri May 11, 2018 2:33 pm    Post subject: 78 924 I need to get running Reply with quote

Hello all, I just bought my first Porsche, a 78 924 NA auto for very cheap from one of my coworkers. He put a lot of money into this car, was driving it every day until it just stopped starting.
He told me it was the fuel pump relay and possibly fuel pump so I put in a new fuel pump and a relay from a newer 911.
Fuel pump wasn’t turning on so I jumped it to battery for the moment. Fuel pump kicks on, car won’t start. Cracked open the banjo fittings on the air box, and fuel is definitely spraying out of each one.
Checked spark at each wire with a screw driver, seems to be getting spark just fine.
Plugs, wires, coil, fuel pump, and cap and rotor are all new. Car is turning over and seems to “cough” like it wants to start, but no luck.

I’m open to all suggestions and advice. Thank you in advance!
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Mr Bitey  



Joined: 23 Sep 2011
Posts: 54
Location: Perth, Western Australia

PostPosted: Fri May 11, 2018 5:22 pm    Post subject: Reply with quote

mmm, maybe check the cold start injector and the warm up regulator (WUR)
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MikesCoupeGT  



Joined: 18 Oct 2006
Posts: 446
Location: Ontario Canada

PostPosted: Sat May 12, 2018 12:11 am    Post subject: Reply with quote

To check the cold start injector, I used to disconnect it on my Audi Coupe. That way it doesn't spray into the cold start injector right when you turn the key. From there you can hold down the throttle until the car starts. Just remember that you increase the chance of flooding it.
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Paul  



Joined: 02 Nov 2002
Posts: 9349
Location: Southeast Wisconsin

PostPosted: Sat May 12, 2018 2:48 am    Post subject: Reply with quote

Check for vacuum leaks, check camshaft timing and belt and ignition timing.
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Silver 98 986 3.6l 320 HP "Frank N Stein"
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Eric P  



Joined: 21 Jun 2017
Posts: 169
Location: NY, USA

PostPosted: Sat May 12, 2018 3:07 am    Post subject: Reply with quote

Try pulling the injectors out of the head. Put them in gas resistant bottles, jumper the fuel pump relay. Find the flow plate located on top of your air box under the rubber intake boot. Make sure that the injectors aren't spraying fuel when the plate is down. When you lift the plate, all injectors should be spraying a fine mist. You should be able to hear them "sing". Check all the bottles to make sure they have the same amount of fluid in them when you're done.

Just remember, you need spark, fuel, and compression. Assuming you have all of them in the correct amounts and at the correct times, it should run.

Start with one and then move on once you verify it's ok.

Another thing to note, I've owned a lot of cars and motorcycles and I've had a few head scratchers that just wouldn't run until I looked into this: For some reason people like to put spark plug wires back on in the wrong order after checking for spark. Always check firing order if you suspect spark as an issue. Somebody could have messed with it before you got in there.
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Slam  



Joined: 07 Jan 2005
Posts: 1692
Location: Wainwright, Alberta, Canada

PostPosted: Sat May 19, 2018 3:58 pm    Post subject: Reply with quote

Check part number on fuel pump relay. 78 needs a specific relay, and I'll bet the 911 one is not doing the job.
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78kate  



Joined: 11 May 2018
Posts: 3
Location: Orangevale CA

PostPosted: Sat May 19, 2018 4:18 pm    Post subject: Reply with quote

Slam wrote:
Check part number on fuel pump relay. 78 needs a specific relay, and I'll bet the 911 one is not doing the job.


Yeah it wasn’t working so I jumped the pump to the battery. It’s kicking out fuel, but still my starting.
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Ian89C4  



Joined: 01 Apr 2011
Posts: 539
Location: North Carolina

PostPosted: Sun May 20, 2018 2:04 am    Post subject: Reply with quote

Is the fuel pump from a 911 with a CIS system? If not, it is not pushing enough pressure.
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Spiveys Corner, North Carolina

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78kate  



Joined: 11 May 2018
Posts: 3
Location: Orangevale CA

PostPosted: Sun May 20, 2018 12:59 pm    Post subject: Reply with quote

Ian89C4 wrote:
Is the fuel pump from a 911 with a CIS system? If not, it is not pushing enough pressure.



The pump is a brand new Bosch OE for the 78 924
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1561
Location: MI

PostPosted: Mon May 21, 2018 3:59 am    Post subject: Reply with quote

Jump the pump, with the airplate at its rest position adjust your AFR screw until the injectors start to spray a bit with the plate at rest and then back the screw off just until the injectors stop spraying..

This will leave you with a setting that will spray fuel with even the slightest airplate deflection..

That's about what you want to get it running and then adjust via dwell method from there, once you get it running..


As Eric P posted an injector test is a very good idea and combined with a full proper CIS pressure test should eliminate any fuel issues..

You can find the complete directions in the hanes manual and probably in a lot of threads on this board..
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