weak spark, won't start

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Jan 20, 2002 | 07:09 PM

xcopterdoc

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From: "tween the cotton and tob

weak spark, won't start

Jan 21, 2002 | 10:49 AM

77sc

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weak spark, won't start

Hey guys,
I posted this under "Electrical" as well.
My '77 was running after swapping in a 351W in place of the 400 and now it won't start. I had it running pretty well, came back after a week and now it won't start. Timing looks about right, spark detected at each plug wire. Spark coming out of the coil is extremely weak, even after replacing it. What should I check? There's not much to it I know, Ign. module, reluctor, pickup, cap, rotor, wires plugs, battery, solenoid, starter. So I wonder which one(s)??
Kenny

Jan 21, 2002 | 12:30 PM

Franklin2

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From: Virginia

weak spark, won't start

Start with the module on the fender. You need a spare one anyway to carry around if it's not the problem.

Jan 21, 2002 | 04:05 PM

77sc

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weak spark, won't start

I've got two spares now, I believe the guy looking at it tried one of my spares. I'kk see if I can get all three tested.

Any thing else? I've had trouble with the pickup in a different Ford truck I had. Anybody know how the pickup and reluctor affect the amount of spark I'm getting?

Thanks, Kenny

Jan 21, 2002 | 08:13 PM

blaxuede

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From: Powell RIver Canada

weak spark, won't start

Do a control module voltage check,

1)with the ignition off, carefully insert a small straight pin in the red module wire. Measuer battery voltage at the battery. attach a negative voltmeter lead to the distributor base and positive lead to the straight pin.
2)turn ignition swithc to RUN position. measure voltage at the straight pin in the red wire. record the voltmeter reading, turn ignition off and remove straigh pin.
3)the voltage at the pin should have read at least 90% of batter voltage. If it's not, check the resistance wire to the ign/switch, resistance in the wire should be between 1 and 1.1 ohms

Jan 21, 2002 | 08:16 PM

sparky

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From: Comox Valley, Canada

weak spark, won't start

That is a better idea....I was going to say run a jumper wire from the battery direct to the coil + and see if it made the spark better

Sparky

>Do a control module voltage check,
>
>1)with the ignition off, carefully insert a small straight
>pin in the red module wire. Measuer battery voltage at the
>battery. attach a negative voltmeter lead to the
>distributor base and positive lead to the straight pin.
>2)turn ignition swithc to RUN position. measure voltage at
>the straight pin in the red wire. record the voltmeter
>reading, turn ignition off and remove straigh pin.
>3)the voltage at the pin should have read at least 90% of
>batter voltage. If it's not, check the resistance wire to
>the ign/switch, resistance in the wire should be between 1
>and 1.1 ohms

Jan 22, 2002 | 08:19 AM

77sc

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weak spark, won't start

Thanks guys,
I remember seeing that procedure in a Haynes manual I had for the 80-86 ford truck I had, but didn't find it in my 73-79 Haynes manual.

Under step #1, I'm just using the distributor housing for a ground point in reading voltage??

The guy that was looking at my truck mentioned previously that I had 12 volt at the coil + terminal. I'll test wires and module and such anyway.

Where exactly is this ignition resistance wire??

Thanks, kenny