4.3 ignition problem

Author Message   larry erb New member Username: bearman Post Number: 1 Registered: 01-2010 Posted on Saturday, January 09, 2010 - 09:51 pm:    Hi all, I have a 94 blue water 18' with a 4.3 mercruiser sterndrive, good oil pressure on the starter, and fuel pressure, I hook a spark plug into the coil lead, I get a single spark, thats it, key off back on, same thing, any suggestions would help thank-you   chiefalen Advanced Member Username: chiefalen Post Number: 503 Registered: 03-2008 Posted on Sunday, January 10, 2010 - 01:30 am:    the battery fully charged? Good connection at the starter? Remove the battery terminal and clean the battery terminal with a battery brush it may look clean but in fact may not be. Try it again? Still no good spark then remove the terminals again and follow the neg cable, to the ground on the block remove and clean. Then follow the pos cable, clean all the connections and don't forget the one on the starter.   Brian Brackett Senior Member Username: kainon Post Number: 1115 Registered: 03-2009 Posted on Sunday, January 10, 2010 - 10:19 am:    Larry.. are you having someone turn the engine over while you check spark? if not you will only get one spark. ( i think )   Guy Gaspar Senior Member Username: guyjg Post Number: 5536 Registered: 08-2006 Posted on Sunday, January 10, 2010 - 11:02 am:    Check for a corroded optic trigger under the rotor. It will cause a "no start" condition. 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.   larry erb New member Username: bearman Post Number: 2 Registered: 01-2010 Posted on Monday, January 11, 2010 - 11:48 am:    thanks for the tips guys, I flipped the kill switch a couple times, an the shift cutout switch on the exh manifold, an she fired right up, whew lucky me thanks again larry   chiefalen Advanced Member Username: chiefalen Post Number: 514 Registered: 03-2008 Posted on Monday, January 11, 2010 - 02:26 pm:    Yes ! Good for you. Maybe a little contact spray on em maybe slightly rusted.

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