No Start + Jolt?

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whalenlg
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Ran the car earlier today and it was great - went to start it now and just get crank but not firing.
Fuel pump not engaging (but works if I jumper the DME relay pins). Tried a 2nd DME relay - no dice.
Next step is to swap the DME, but something else perturbed me.
After one failure to start, I just turned the ignition to ACC, to see if I could hear the Fuel Pump going (nothing), but there was a small jolt. That kind of concerned me so I disconnected the battery.

Anyone else feel that before?

Thanks!
1986 951 - Silicon Valley

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whalenlg
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FWIW- most recent work was replacing the clutch master and slave this week, so the starter was removed, but cables not disconnected
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Tom
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What do you mean by Jolt??

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whalenlg
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When I turned the key to acc, subtle rock of the car. Like maybe the starter for a very short impulse? But just momentary.
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Tom
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Hmmm, odd, ignition switch might be bad but i'd rule out the usual suspects first. Did you have tach bounce?

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whalenlg
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yea - I did see slight tach bounce when cranking. How much bounce is normal?
Also - bench tested the original dme relay per clarks garage procedure. Seems fine.

I reproduced the jolt by moving the key from acc to on (not to start). Seems like the starter pulsed, so I’ll check that wiring next
Last edited by whalenlg on Fri May 23, 2025 9:58 pm, edited 1 time in total.
1986 951 - Silicon Valley

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Tom
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Bounce is a misnomer -- it's more of a tach twitch...

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Tom
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Does the boost gauge go to 1 when you turn the key on? It is powered by the KLR so a good proxy for whether the dme and klr are getting power.

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whalenlg
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Boost gauge stays stuck all the way left even when cranking.
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whalenlg
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Fuse 34 is good as well
1986 951 - Silicon Valley

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