Mercruiser 4.3L Will Not Start

[alehman]

I am new to this forum but have read a lot of great advice from people. I have a Mercruiser 4.3L engine that ran fantastic last season. I winterized the boat and when I tried to start the engine it would not start. I have now changed the starter, the distributor cap, the rotor, the sensor assembly, the ignition coil kit, all the spark plugs and wires. I have tested that I have 12v at my coil when the engine is turned on and my inline spark plug reader lights up for each of my plugs but the engine will not turn over (belts moving but not pop). Not sure how this is possible unless the spark is not strong enough to jump the gap (all gaps set with a feeler gauge).

 

[flashback]

Looks like you changed everything but the battery, does the engine turn over ?

 

[alehman]

Sorry. Two new batteries as well. The belts start turning but no spark.

 

[flashback]

Is it getting good fuel, you mentioned your spark tester is reading good..

 

[alehman]

Yes. Water/ Fuel separator changed and fuel can be seen in carborator.

 

[flashback]

Compression test could help.

 

[1985 Century Mustang]

Did you try spraying Carburetor Cleaner in the carb. You could have a fuel issue. I'd try that first.

 

[Scott Danforth]

We know you can change parts, however what trouble shooting steps have you taken?

Have you followed the thunderbolt ignition troubleshooting guide? (It's in the stickies)

 

[flashback]

Yep it's time to give some details of what you have like serial # and year.

 

[alehman]

Did you try spraying Carburetor Cleaner in the carb. You could have a fuel issue. I'd try that first.

I tried that several times after each fix I tried.

 

[alehman]

Yep it's time to give some details of what you have like serial # and year.

serial number is 1a069772 and year is 1990. It was repowered in 2018

 

[flashback]

serial number is 1a069772 and year is 1990. It was repowered in 2018

I'm shade tree like you but those details will be helpful for those in the know...

 

[alehman]

We know you can change parts, however what trouble shooting steps have you taken?

Have you followed the thunderbolt ignition troubleshooting guide? (It's in the stickies)

 

[alehman]

I have followed the troubleshooting guide. What is strange is I get less than a volt at the red white wire from the distributor when the key is in the on position. The guide says you should get 1 to 12

 

[alehman]

I checked that I am getting a spark to each plug. Is it possible that either the charge is not enough or that the carburetor is not letting sending enough fuel to the cylinders?

 

[Scott06]

I checked that I am getting a spark to each plug. Is it possible that either the charge is not enough or that the carburetor is not letting sending enough fuel to the cylinders?

Yes you are either missing spark or fuel or compression.

Would check the strength of spark with an inexpensive spark gap tester. should jump 3/8 " or more.

Have you dumped gas down carb to see if it fires? if it does that would indicate spark is ok and you are missing fuel.

As a sanity check do you have compression?

 

[1985 Century Mustang]

Check your main ground.

 

[alehman]

Check your main ground.

I have checked the engine grounds? Is that what you mean?

 

[1985 Century Mustang]

I checked that I am getting a spark to each plug. Is it possible that either the charge is not enough or that the carburetor is not letting sending enough fuel to the cylinders?

No, if you sprayed the carb with carb cleaner or starter fluid, and you had enough spark, it should kick over.

 

[1985 Century Mustang]

Does your boat crank? If so, Have you tried a multimeter to test volts etc? What does your battery read with regards to volts with multimeter? It should read a bare minimum of 12.5 volts.