Mercruiser 4.3L Will Not Start

[alehman]

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.

I have sprayed the carb with starter fluid and nothing. I am getting a spark at each plug but my guess is it is not enough (spark is orange not blue). I ordered an adjustable spark plug tester that I can see how strong the spark is. I have tried a multimeter and my batteries are reading about 13.5 volts at the start. They are brand new and fully charged.

My ground is showing corrosion so I am going to try to clean this up to see if this is eating away at some of my voltage. Maybe this is why the charge is not enough at the plugs?

 

[alehman]

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.

The battery reads 13.5 volts when measured from the positive terminal to ground when the key is in the on position

 

[alehman]

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?

I checked the strength of the spark and I can only read a spark at about 30kV. Nothing higher which I know is low. Just can not determine why

 

[Scott06]

I checked the strength of the spark and I can only read a spark at about 30kV. Nothing higher which I know is low. Just can not determine why

I actually think 30 kv is ok how big a gap is that ? is it blue or light /orange in color? this is at the plugs or coil? if at coil check plugs to ensure you are not loosing spark in distributor

This denso article lists 10-30 kv as normal spark strength

Spark and Ignition | Basic Knowledge | SPARK PLUG | Automotive Service Parts and Accessories | DENSO Global Website

An explanation of the mechanism of producing a strong spark between terminals to cause combustion of the air-fuel mixture.

www.denso.com

At this point I would dump a little gas down carb and see if it coughs, may want to loosen and twist distributor to see if timing is off. Bump the engine with dist cap off to make sure rotor is turning.

Did you check compression? ok to do cold in this case

 

[alehman]

I actually think 30 kv is ok how big a gap is that ? is it blue or light /orange in color? this is at the plugs or coil? if at coil check plugs to ensure you are not loosing spark in distributor

This denso article lists 10-30 kv as normal spark strength

Spark and Ignition | Basic Knowledge | SPARK PLUG | Automotive Service Parts and Accessories | DENSO Global Website

An explanation of the mechanism of producing a strong spark between terminals to cause combustion of the air-fuel mixture.

www.denso.com

At this point I would dump a little gas down carb and see if it coughs, may want to loosen and twist distributor to see if timing is off. Bump the engine with dist cap off to make sure rotor is turning.

Did you check compression? ok to do cold in this case

The 30kV is being measured at the spark plug boot and the spark looks orange in color. Compression looks good.