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-   -   Rev counter means dme relay and crank sensor okay, right? (http://forums.pelicanparts.com/porsche-911-technical-forum/1141391-rev-counter-means-dme-relay-crank-sensor-okay-right.html)

RobFrost 06-09-2023 02:27 PM

Rev counter means dme relay and crank sensor okay, right?
 
Went for a blast in my 3.2, turned up a hill and felt power loss. Ground to a halt at the side of the road.

Wouldn't start, though it was trying. I popped off the top of the three connectors on the left, and then it started and ran for another two minutes but losing power as if timing or mixture was incorrect and then died again. Now it won't run with that connector on or off. I left it to cool, still no start.

Rev counter hits 3k while turning over, so I assume that means dme relay and crank sensor are OK, right? I haven't checked voltage over head temp sensor but since the e gone cooled, it can't be that.

I had just filled with petrol. Certain I didn't put diesel in. There's no such thing as bad petrol, right?

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dtxscott 06-09-2023 07:26 PM

You will need to check the sensors. A volt-ohm meter should read ~1kOhms across the bottom two terminals of both the crank and reference sensor. The sensors are identical.

Any other reading indicates a failed sensor.

3k when cranking sounds way too high. This could be indicative of a failed/failing sensor.

RobFrost 06-09-2023 08:41 PM

Thanks. It's always cranked fast. High torque starter motor, I suspect.

Pulling the CHT would make it run richer, i presume? I suspect this is a fuelling issue.

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RobFrost 06-10-2023 04:34 AM

Quote:

Originally Posted by dtxscott (Post 12019571)
You will need to check the sensors. A volt-ohm meter should read ~1kOhms across the bottom two terminals of both the crank and reference sensor. The sensors are identical.

Any other reading indicates a failed sensor.

3k when cranking sounds way too high. This could be indicative of a failed/failing sensor.

I'm getting 0psi fuel pressure while cranking. I assume this is incorrect?

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917_Langheck 06-10-2023 07:07 AM

Failed DME relay.

RobFrost 06-10-2023 07:45 AM

Quote:

Originally Posted by 917_Langheck (Post 12019745)
Failed DME relay.

Thank-you for your help. I verified at the fuel pump fuse that its power was being switched correctly with the ignition, so dme relay fine. I verified 0psi prior to the fuel filter.

I checked fuel pump for noise, it was just clicking. It turned out to be a seized fuel pump.

A dose of percussive maintenance solved the problem, at least temporarily.

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grb008 06-10-2023 09:09 AM

if you have 0 fuel pressure either the fuel pump isn't turning on(DME or fuse), Bad Feul Pump(hot wire the pump to get it going bypassing the relay and see if it starts) or your regulator is shot and dumping all the fuel back to the tank. You measured the pressure at the rail port?

I missed the part about the seized pump, sounds like you found it.


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