2002 Mercruiser 4.3 Just Cranks no start

P

Phil Chieco

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Joined
Jun 25, 2001
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5084
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Hello, My son was out on the water yesterday and when he went to start the boat it just cranked and did not start. He was towed back and I check the fuel and also if it was getting fuel. Yes to both. I'm not quite sure how to check the coil and was hoping for some help. Boat has 275 hrs on it. I have never replaced the distributor, coil or spark plug wires. Boat has always been trailered except for this year. Its in the water. I plan to check fuses in the am. Thank you Phil
 
Classic Kill Switch. Make sure it's not off Normal (Run). Cycle it to OFF a couple times.

If it's Killed, it'll crank but not start, AND the Gauges will look like the Key is OFF.
 
I checked the kill switch with it in the normal position all gauges work. I'm about to check the ignition sensor using these instructions. - 12 volts are present, remove the coil spark wire from the distributor and connect it to a spark gap tester to ground.b 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. If I understand this correctly, There will be no coil plug wire hooked to the distributor, however I will hook the coil plug wire to the tester and take the end of the tester and ground it. The white green wire can be disconnected as its shielded and I will take the end which is the end that does not go to the distributor and touch that to ground. I'm assuming the tester will either light up or not when I touch to ground or will I get an actual spark.. Is this a correct understanding. I just don't want to screw anything up. Thanks
 
If you have an inductive timing light , just put the clamp on the spark plug wires and crank to see if it flashes brightly.

Is this a carbed motor or TBI ?
How did you confirm it was feeding gas to the cylinders? And is it good gas( with strong gassy odor), ... or stale or phase-separated E10 & water ?

If the 2002 15 yr-old engine has never had new dist. cap, rotor & plugs and timing checked, it's waaaaay overdue.
 
Unfortunately I do not have a timing light. this is a carbureted motor with a thunderbolt ignition. The gas is fresh as I've been using the boat all season. Now I want to confirm if it's the sensor or the coil is bad. I have replaced the distributor and rotor. the plugs were done a few seasons ago. Water separator done last year as well as fuel filter. The spark plug wires have never been changed but the motor only has 275 hours on it and it's always been trailer and covered. I was just thinking of replacing the sensor and the coil but if I could rule out one it would save me a few dollars.
 
You could start by seeing if you have spark by grounding any plug wire out on the block while cranking.
 
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