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Relay Swap??
My 73 911 S was running fine yesterday. Today it wouldn't start. Starter spins engine over. I am suspecting fuel pump relay, because pump doesn't run when ignition is on. Can I swap either the horn or driving light relay to test my theory?
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11-21-2010, 04:28 PM
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Join Date: Oct 2003
Location: Michigan
Posts: 14,093
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yep
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1981 911SC ROW SOLD - JULY 2015 Pacific Blue Wayne |
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11-21-2010, 04:30 PM
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Still doesn't start, but left key on while removing relay and pump runs while only 2 of the pins are in socket.???
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1977 911S silver/black |
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11-21-2010, 04:34 PM
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Fuel pump.......
Quote:
The '73 models don't have FP relay!!!!! Chech the terminals of the FP to determine if it has power and good ground to begin your investigation. Lastly, bench test the FP, it might be bad after all. HTH. Tony |
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11-21-2010, 09:40 PM
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Band.
Join Date: Dec 2003
Location: Denver, CO
Posts: 13,367
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What Tony said.
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11-21-2010, 09:51 PM
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Sorry, the 73 was a typo, I have a 77. I have ordered a shop manuals. Until I get them, what is a a systematic rundown of the most common reasons that my car won't start. I have a Permatune ignition. How do I trouble shoot that system? It's either spark or fuel, I know that much. It was running great the day before. Thanks.
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1977 911S silver/black |
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11-22-2010, 05:21 PM
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Troubleshooting.........
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Steve, You could check the fuel side by testing your FP either volumetric or pressure. A fuel pressure gauge will tell you the delivery pressure. Or measure the flow rate (liter/min.). A minimum of two (2) liter per min. is needed. Even with a good fuel pump, without spark or ignition, the engine won't start!!!! So before you do any further investigation, double check or triple check that there is a strong ignition spark during cranking of the starter. Inspect carefully all your ignition wires to the CDI and coil. Make sure everything is properly connected and in good condition. Your primary goal is to see that the ignition system is producing bright ignition sparks at the spark plug/s. Without this (spark), there will be no internal combustion!!!! Regardless whether you have Bosch or Permatune CDI, the presence of ignition sparks is necessary for complete combustion. A simple procedure I like to use for ignition troubleshooting is to use a known working CDI in place of the suspected unit. Keep us posted. Tony |
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11-22-2010, 06:27 PM
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Found the problem. This car is fairly new to me..6months. I was counting on the low fuel light to illuminate as it has in the past..short story..OUT OF GAS! Thanks for all of the help.
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1977 911S silver/black |
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11-22-2010, 07:34 PM
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Wine User
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LOL...note to self.
1st thing to check. 2nd... |
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11-22-2010, 07:41 PM
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Not available.........
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Steve, I don't think your car has that option!!!!! I maybe wrong and I've been wrong many times before but I don't see it on any of the wiring diagrams so far. Please advise. Tony |
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11-22-2010, 07:43 PM
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Mine does, its on page 20 of the owners manual , as well.
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1977 911S silver/black |
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11-22-2010, 07:53 PM
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Porsche Carrera
