Mercruiser 4.3L Aplha 1, Gen 2 starting issues

[Davidmartin5665]

Hey guys. I apologize for such a long post but I want to make sure I have as much info as possible and fully explain the situation.

I just bought a mercury mercruiser 4.3 alpha 1 Gen2 stern drive chaparral. Had it out a total of 5 times and it ran great! About 2-3 weeks ago I was tubing and my mom plained the boat and then shut it off while coasting. Wouldn’t start back up. Got a tow back and just started troubleshooting it. Engine wouldn’t crank. Starter just clicked. Replaced the starter. Cleaned the connections. Finally turns over but does not start. Checked the spark plugs and initially thought they were wet with water. Smelled them and it was fuel. Blew out the cylinders with compressed air through the plug holes and put in new plugs per the service manual. Still won’t start, just turns. Tested the new spark plugs and they all apear to be sparking. Checked the carb throats and the jets pump fuel into the carb when advancing the throttle. I have not been able to run a compression test yet and forgot to check the wire harness. Will check that tomorrow.

I was initially working under the theory the flappers were bad because I though there was water in the cylinders but that does not appear to be the case. Oil is at a good level and does not appear to have water. Gear lube appears to be at good level. ATF fluid was extremely low but I have since filled that. Any help would be extremely helpful. I have attached some pictures but the video of the engine cranking was too big.

Thanks!

 

[alldodge]

plained the boat and then shut it off while coasting. Wouldn’t start back up. Got a tow back and just started troubleshooting it. Engine wouldn’t crank. Starter just clicked. Replaced the starter. Cleaned the connections. Finally turns over but does not start.

Tested the new spark plugs and they all apear to be sparking.

How was this checked?

Checked the carb throats and the jets pump fuel into the carb when advancing the throttle.

My guess is the motor took on water from stopping abruptly. Need to take all plugs out and crank the motor over a few times. If it doesn't start after that, go thru the TBV troubleshooting guide

 

[Davidmartin5665]

Thanks for the reply.

I have an update but figured I would respond to your post first. spark plugs were replaced and "tested using a gap/in line spark plug tester. Discovered that this can lead to a false positive because the thunderbolt 5 system can send enough volts to spark the tester but not enough for the spark plug to bridge the gap.

Update: I followed the flow chart. Had 12v running at ignition coil. Also had 12v on lead coming from module. Ultimately had no spark at coil after grounding out the white green lead with the gap tester. Will be getting a new ignition coil and running test again tomorrow.

I also am not sure on the water intake theory. Have no water in cylinders, etc. but could still be possible i guess. Will be checking the shutters once i get the thing to start. Also ran a "compression test" and the pressure blew my finger off the spark plug hole so I don't think compression is an issue.

 

[Rick Stephens]

10 PSI will blow your finger off the hole.

 

[achris]

... Ultimately had no spark at coil after grounding out the white green lead with the gap tester. ...

You won't get a spark by 'grounding out' the wire, you need to have it on and off ground (about 3 or 4 times a second) to simulate pulses so the module will then fire the coil.

Chris......