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-   -   Cranks but won't fire (http://986forum.com/forums/performance-technical-chat/72026-cranks-but-wont-fire.html)

aussieboxy 05-03-2018 02:22 PM

Cranks but won't fire
 
Jumped in the car this morning & it cranks fine but won't fire.

It's obviously electrical but not sure what the possibilities are.

Will start with fuses & go from there.

Any assistance would be greatly appreciated.

Spinnaker 05-03-2018 03:55 PM

Take off the gas (petrol?) cap and listen at the fill neck for a whirring sound when the ignition is turned on. If there is no sound, then the fuel pump is not working. Check the fuse first.
When the engine is cranking, does the tachometer show any revs? If not, then the crank position sensor is not working.

Jgkram 05-03-2018 04:31 PM

I had the same situation several months ago. Diagnose this methodically. Think spark, fuel and then air/electrical. If fuses check out and it's not the crank position sensor then start with spark. Easy to pull a coil pack and shove a grounded plug into it and crank the engine. Look for a nice blue spark.

Next pull the fuel pump relay and jumper it. It's another check to what Spinnaker said but with your head in the footwell, you should hear the pump turn on as soon as you jumper the relay. If the pump runs, you're probably getting fuel so Che k the relay for continuity and function. Energize it and see if it clicks (relays are making contact). If not, bad relay. Just because your fuel pump runs doesn't mean you are getting fuel (ask me how I know). Check fuel pressure. My problem turned out to be a stuck fuel pressure relay. Good luck...

BFeller 05-04-2018 05:05 PM

CPS sends a tach signal. IIRC from when mine died - you should see a blip on tach if it is sending a signal. On the other hand - my original durametric worked only once and that was able to I’d the failed CPS.


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