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I'm a Registered User!
Join Date: Jan 2008
Location: Colorado
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'76 911S Backfire + Die
Hey all,
I have a 1976 911S that sat for about a year. It was started about every month and sometimes driven for short drives. However, on the last drive it backfired and died. I cannot restart it. I have not tested anything yet, what should I look for first? Obviously I should check for spark and gas, is there anything that would sound like it broke? Thanks, Greg
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1983 280ZX N/A 2-Seater T-Top red w/ black + silver interior 1986 Volvo 740 GLE - RallyCross Car 1976 Porsche 911S Euro-spec, Black on Black on Black |
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11-08-2009, 02:28 PM
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I'm a Registered User!
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Location: Colorado
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I have read this can be cause by the coil going out. I am going to be checking it with a multimeter later tonight, does anyone know the resistance specifications for the coil?
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1983 280ZX N/A 2-Seater T-Top red w/ black + silver interior 1986 Volvo 740 GLE - RallyCross Car 1976 Porsche 911S Euro-spec, Black on Black on Black |
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11-08-2009, 03:36 PM
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Go Speedracer, go!
Join Date: Aug 2002
Location: Indianapolis
Posts: 1,951
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Not sure about the coil resistance.
76 is CIS right? It could be a blown air box. Do a search for blown air box or cracked air box. You'll see plenty of pictures and how to tell if that is what happened.
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1981 SC ROW Coupe |
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11-08-2009, 03:54 PM
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Registered
Join Date: Oct 2005
Location: Capistrano Beach, Ca.
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Agree that blown air box, stuck pop-off valve (if you have one), or air leak from backfire is likely cause. Do check for spark first, however. If present, you likely have a massive air leak which prevents the car from running.
Question: When cold, does the car fire-up and immediately die or is there no firing at all in the engine?
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L.J. Recovering Porsche-holic Gave up trying to stay clean Stabilized on a Pelican I.V. drip |
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11-08-2009, 04:41 PM
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I'm a Registered User!
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I'll check the air box as well tonight. I remember looking around right after it happened and not noticing anything wrong with the air box.
It does not start cold but it turns over nicely. Also, if I remember correctly, the gauges went kind of haywire prior to it's death if that gives any info.
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1983 280ZX N/A 2-Seater T-Top red w/ black + silver interior 1986 Volvo 740 GLE - RallyCross Car 1976 Porsche 911S Euro-spec, Black on Black on Black |
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11-08-2009, 05:55 PM
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Designer King
Join Date: Mar 2004
Location: Toronto, ON Canada
Posts: 5,499
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Check the points first.
Check all other electrical and ignition items. Check for vac leaks. Check the fuel injection incl the WUR and fuel & control pressures
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Paul Yellow 77 Sunroof Coupe/cork interior; 3.2L SS '80 engine/10.3:1/No O2; Carrera Tensioners; 11 Blade Fan; Turbo tie rods; Bilstein B6; 28 tube Cooler; SSI, Dansk; MSD/Blaster; 16x7" Fuchs/205/50 Firestone Firehawk Indy 500s; PCA/UCR, MID9 Never leave well enough alone |
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11-08-2009, 07:05 PM
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Checked out
Join Date: Jun 2009
Location: On a beach
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your airbox is cracked, or something related has blown off, and you now have a massive vacuum leak that is preventing the car from starting.
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11-08-2009, 07:18 PM
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I'm a Registered User!
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Box is not broken. I will have to look for other vacuum leaks when there is light outside since my cellphone light is not cutting it at 1AM
 I will also look at the other things suggested, thank you very much for ideas! As for the coil's resistances... Between terminals 1 and 15 the resistance was 3.7 ohms Between terminals 4 and 15 the resistance was 8.7 kohms According to below, between terminals 1 and 15 is pretty off. Is that a big enough difference to be causing this? I might try cleaning the connections tomorrow on the receiving end of the coil. Quote:
Factory Coil Output
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1983 280ZX N/A 2-Seater T-Top red w/ black + silver interior 1986 Volvo 740 GLE - RallyCross Car 1976 Porsche 911S Euro-spec, Black on Black on Black |
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11-08-2009, 11:13 PM
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I'm a Registered User!
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Updates:
Checked the air box (wow it's clean in there!) and most of the hoses near that. They all seem great. I changed the coil with one from my Datsun since their ohm readings were within spec. Tried to start it with no success but I did notice a gas smell from the exhaust so we're good on gas. I then decided to check into the coil's power a bit more. There is no electricity going to the coil! Now I'm going to be searching about that. (Sorry, don't have a manual so I just gotta keep searching) Will let you all know what happens!
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1983 280ZX N/A 2-Seater T-Top red w/ black + silver interior 1986 Volvo 740 GLE - RallyCross Car 1976 Porsche 911S Euro-spec, Black on Black on Black |
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11-09-2009, 10:44 AM
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Registered
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Location: Valencia Pa.
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Check the air box a little more carefully, take off the cover , and the air cleaner, there are small flat head screws in the bottom , and after an air box explosion, these are commonly sticking up out of the plastic.
But I guess if you have no spark, you have to take care of that first .
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11-09-2009, 10:50 AM
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The box is fine, all of the screws look great and everything is solid up top. It is definitely not getting spark. I think it is points or CDI related.
EDIT: It was the points! Tomorrow = checking dwell. Thanks for all your help, it could have been anything so any clues or directions to take were very helpful.
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1983 280ZX N/A 2-Seater T-Top red w/ black + silver interior 1986 Volvo 740 GLE - RallyCross Car 1976 Porsche 911S Euro-spec, Black on Black on Black |
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11-10-2009, 03:00 PM
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