4.3L vortec no fire?


Old 01-01-04, 10:06 AM
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Question 4.3L vortec no fire?

Am working on a 77 GMC Sierra pickup which has been
retrofitted with a 4.3L vortec V6 engine, with 2 barrel carb,
distributor with built in coil and vacuum advance, Carter electric fuel pump, electric cooling fan with relay.

Per the teaching of this forum " Basics", I have fuel, air, but no spark.

The engine crank and ran for a while with a CCM distributor but then failed to crank for lack of being able to advance.

Then installed new appropriate distributor with vacuum advance but still unable to get fire.

Would appreciate all advice and help. Thanks for your time and consideration.
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Old 01-01-04, 12:05 PM
Desi501's Avatar
Join Date: Oct 2003
Location: Boynton Beach Florida
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First you need to check for 12 volt power supply to distributor terminal. If you do, then you need to check for tach signal from the tach terminal at the distributor. If you have a tach signal, blame the coil. If you have no tach signal them you have either a bad module or pick-up in the distributor. Since the modules have a pretty bad reputation, I'd probably try that first.
Old 01-03-04, 08:48 AM
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4.3L V6 not firing

Checked power to distributor; got a constant reading of 11.88 volts. Had ignition module tested it passed- 3 times consecutively.

Don't have a factory or aftermarket tach. What kind of reading should I get from tach side of cap? Check for ohms (unpowered) or turn ignition on and check voltage to tach terminal?

The cap doesn't seem to be suspect. Would it be prudent to change rotor button?
Not to sound igorant but when you referred to pick-up in distributor, where you speaking of the short cylinder silver item?

All suggestions and help are appreciated. Thanks in advance for your time and consideration

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