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Still No Spark! Help 1987 350

T

traub

New member
1987 - 350Mag Alpha GM V8 (sn B605821) - Always ran great. Sat about a month last year during a rainy summer. went to start and no spark. Pulled coil wire to see if I was getting a spark and eventually it sparked and fired up. Still raining so I pulled boat for the winter. Now, I've replaced the coil and ignition sensor in the distributor. I have 12v on purple/hot side of coil. I pull the coil wire out of the top of the coil, stick a screw driver in the top of the coil and then place the coil wire I just pulled out right next to the screw driver. Turning the engine over I get no spark. The only time I get a spark is if I turn the key to the on possition (not all the way over to actually turn the engine over) then turn it back to OFF, I see a spark jump from the coil wire to the screw driver sticking out of the top of the coil. I can click the key back and forth, and every time I get a spark going to OFF. If there was a kill switch or a funky shift cut off switch, I wouldn't be getting 12v to the coil right? Plus I jumped the shift cut off switch and ohm'd the wires too. The only thing left is the expensive ingintion module but from what I've read here, that's really rare. The local parts guy said he's never sold one. What am I missing?
Any suggestions are greatly appreciated!
 
Re: Still No Spark! Help

Try removing your ignition switch and if POSSIBLE dissassemble it and clean the internal contacts.

Other wise get a new ignition switch.

Start theory 101....... thunderbolt IV, V

when you turn the key to the crank/start position the key switch controlls the power distribution from the +12volts comming into the switch to the yellow with red stripe wire that powers the solenoids and starter selonoids. it also get internally jumped to the purple wire to power the coil, (run curcit is temporarly activated)

When you release the key in springs to the RUN position. in this position the +12 volts is distributed to the purple run curcit wire that goes to almost all guages and coil and choke.

The nuetral safety switch would not allow the engine to crank over at all,

The shift interuptor switch grounds out the ignition when activated, ( if you jumped the two wires together then you shorted your ignition to ground = wont work)

If you review a few earlier posts there is a proceedure to PROPPERLY test the thunderbolt IV ignition......... Maybe someone will post the proceedure as I do not have it here.

LOOSE THE SCREWDRIVER and buy some real spark checking tools...........and a 12 volt TEST LIGHT
 
Re: Still No Spark! Help

Tests for Thunderbolt Ignition:


W/ignition key on AND BILGE WELL VENTILATED OF GAS FUMES!!!


Check the kill switch first!


#1 - Connect your voltmeter neg. lead to the engine ground and pos. lead to the white/red wire terminal at the dist. It should read 12 volts.

#2 - If 12 volts are present, remove the coil spark wire from the distributor and connect it to a spark gap tester to ground. Remove the white/green lead from the dist. terminal. Turn the ign. key to on and strike the white/green lead to ground. If there is spark, replace the ignition sensor in the dist.

#3 - If there is no spark, substitute a new coil and repeat test #2. Now if you get spark, install a new coil. NO SPARK, replace ign. amp.

#4 - In #2, if there is No voltage present, disconnect the white/red wire and check it again for 12 volts. If 12 volts is present, replace the ignition sensor inside the dist. cap. If no 12 volts present w/it disconnected--ignition amplifier is shot and must be replaced.
 
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