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3.2 Spark Problem
I swapped a 3.2 into my '76 a couple of months ago and have been chasing a hard starting problem ever since. Once it starts, it runs great - just getting it started is the hard part.
I have gone through and checked nearly everything (all components, voltages, resistances, pressures etc. are in spec), but was goofing around last night and thought I would see how strong the spark was. I found the problem... When the car is cranking, there is *no* spark. Only when the key is released (back to the "run" position) does a nice, strong, blue spark jump the gap. I have spent some time looking at the wiring diagram, but so far nothing is jumping out at me. Anyone have any idea what could cause this "no spark when cranking" problem? Thanks, Mike
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Mike 1976 Euro 911 3.2 w/10.3 compression & SSIs 22/29 torsions, 22/22 adjustable sways, Carrera brakes |
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08-21-2003, 04:08 AM
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Join Date: Nov 2001
Location: a few miles east of USA
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ignition sw?
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Rich  '86 coupe "there you are" |
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08-21-2003, 04:34 AM
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Location: Peoples Republic of Long Beach, NY
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but there is a leg on the sw. that does not supply current in the "start" mode.. it'll only supply current in the "on" position. again it's only a guess on what may have happened during the install for feeding the DME........Ron
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Ronin LB '77 911s 2.7 PMO E 8.5 SSI Monty MSD JPI w x6 |
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08-21-2003, 04:41 AM
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Well, I hesitate to suspect the ignition switch since the car cranks properly (starter spins).
Mike
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Mike 1976 Euro 911 3.2 w/10.3 compression & SSIs 22/29 torsions, 22/22 adjustable sways, Carrera brakes |
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08-21-2003, 04:53 AM
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Location: Wallenstein, Ontario, Canada
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As mentioned by Ron it is most likely how the DME harness (chassis side) was integrated into the car
Tem 86 on the DME relay is a switched ignition source. Depending on where you are picking that source up it may not be getting 12V while cranking. There are several circuts to which power is shut down going from the run position to cranking position on the ignition switch. Todd
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1989 911 Targa |
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08-21-2003, 05:21 AM
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Thanks. I've got some things to check, but it seems that - for whatever reason - the DME isn't getting powered during cranking....
Mike
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Mike 1976 Euro 911 3.2 w/10.3 compression & SSIs 22/29 torsions, 22/22 adjustable sways, Carrera brakes |
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08-21-2003, 06:57 AM
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You might want to PM marcesq to review what you did in the conversion. He did a 3.2 conversion that seems to have worked out fine.
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Dan Morissette '85 Guards Red Targa 911 My Owners Gallery Page Non illegitimi carborundum |
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08-21-2003, 07:07 AM
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 Yeah, I used marcesq's web page pretty extensively when I installed the engine. My problem is primarily that I am a *mechanical* engineer and this electrical crap blows my mind....Thanks, Mike
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Mike 1976 Euro 911 3.2 w/10.3 compression & SSIs 22/29 torsions, 22/22 adjustable sways, Carrera brakes |
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08-21-2003, 07:30 AM
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Quote:
if the DME is getting current from the ignition sw leg that's NOT supplying current during the "start" position, Then blah, blah, blah
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Ronin LB '77 911s 2.7 PMO E 8.5 SSI Monty MSD JPI w x6 |
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08-21-2003, 12:38 PM
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1976 Porsche 911
1985 Porsche 911 Targa 3.2
