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Join Date: Jul 2008
Posts: 105
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78 SC not starting
I have searched may threads and they all seem to offer good advice but I am confused in what to check first and if it applies to my car. Can anyone point me in the right direction?
Preamble: Driven daily No starting problems, no intermittent cut out, all good Fuel pump replaced 2 months ago due to Stock coil, CDI, etc. No Permatune device Plug leads good WUR good Pre DME car Problem: Will not start now (was fine 3 hours earlier) Symptoms: Starter motor turning fine but will not fire engine Problem analysis to date: Checked voltage at coil and NOT getting 12v - Some articles in the forum suggest that I should not be getting 12v here, but a pulsed 450v is this correct and if so how do I check for this? Green wire 'looks' fine, how do I check this properly? Some articles imply this wire is co axial, on mine it looks like any 'normal' wire - What's all the fuss about this wire? Relays look good Fuses look good Questions: What should I check? What order should I check things? Is there a wiring / current flow diagram that I could get my hands on? Thanks 
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01-24-2009, 12:07 AM
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Join Date: Nov 2004
Location: Raleigh, NC
Posts: 3,864
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Swap the red fuel pump relay with the black and see if it starts.
If not, turn the ignition on, reove the air filter, and push up on the arm of the airlow meter and listen for the sound of the pump running.
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John D. 82 911 SC Targa-Rosewood 2012 Golf TDI |
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01-24-2009, 03:39 AM
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Wer bremst verliert
Join Date: Jan 2005
Location: Toronto, Ontario
Posts: 4,767
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John got you started...you need to check the basics of fuel, spark and compression (last not a likely issue.)
Follow John's advice above regarding fuel. If you are getting fuel then... If you have a timing light hook that up and see if you are getting a spark. Pull one of the plugs right after trying to start it and sniff it..do you smell gas?
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2007 911 Turbo - Not a toy 1985 911 Cab - Wife's toy 1982 911 3.2 Indiash Rot Track Supercharged track toy 1978 911 3.0 Lichtbau toy "Gretchen" 1971 911 Targa S backroad toy |
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01-24-2009, 03:54 AM
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Join Date: Jul 2008
Posts: 105
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Fuel pump working ... I am pretty convinced this is an electrical fault
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01-24-2009, 08:04 AM
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Join Date: May 2005
Location: Austin, TX
Posts: 909
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As JohnJL said try try this
If you have a timing light hook that up and see if you are getting a spark. To test the green wire, take a look at this thread http://forums.pelicanparts.com/showthread.php?t=334432&highlight=test+green+wire check the proper pins on the cdi plug for the resistance on the green wire. And also check this thread http://forums.pelicanparts.com/showthread.php?t=452781 another 78SC not starting. Good luck. Jay
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2002 Boxster Speed Yellow |
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01-24-2009, 09:02 AM
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Join Date: Jul 2008
Posts: 105
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Thanks for the tips guys.
After a fair bit of rooting around, I took the connector out of the bottom of the CDI. Tested the connections as per this post: http://forums.pelicanparts.com/showthread.php?t=203100 It all checked out fine. I put the connector back on again and, hey presto, it sprang back to life. I can only assume it was a bad/loose connection that caused the problem. Lets hope it doesn't happen again or it isn't a sign of future problems. Thanks for your input and ideas |
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01-24-2009, 10:09 AM
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Join Date: May 2005
Location: Austin, TX
Posts: 909
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Great, but don't get too far from home till you've thoroughly wiggled those connectors or let it get hot!
O h I got about 4 miles from home before mine died when I had a similar problem  .Jay
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2002 Boxster Speed Yellow |
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01-24-2009, 11:48 AM
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| ignition , starting |
