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rick-l rick-l is offline
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Join Date: May 2002
Location: St Louis
Posts: 4,211
To clarify what was said above the fuel pump runs whenever the key is in the start position and if the DME senses the engine is running it continues to provide a signal to the pump relay.

An 8051 microcontroller whas very high tech in the early 80's. OBDII in 1980? What kind of a PC did you have in 1980?

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Originally Posted by logician View Post
Great suggestions everyone. I'm trying to queue up a bunch of things to try when I go to my shop later today.

Question: how does the DME determine if the engine is turning over and so to enable fuel? Some cars do that via the air box, so if the computer sees any airflow, it knows the engine is turning over. Is this what the 911 DME does? Or does it use other means (the crank sensor, etc?) I'm trying to understand if a bad air box could be a scenario.

(Missing OBD2... it seems unfathomable these days that anyone would design a computer controller without any diagnostic ability.)
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Rick
88 Cab
Old 04-23-2014, 09:33 AM
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