120 hp mercruiser

[Q8tMike]

Guy/gals I recently bought a boat, it has a 120 hp mercruiser for a motor. I can not get this thing to run. I'm just basic skills oil/spark/compression check etc.. I can do and have done.
New spark plugs, new oil/ filter, new gas, took caborator off and completely broke down and cleaned it, fuel pump off and good, water pump below the thermostat off and back on good, water thermostat good compression all the same pressure.
It just cranks and almost starts but can't get it to go run.
Any words of advice. I'll try and post video of it if I can figure out how to do so, of it cranking to help

 

[Rick Stephens]

If you can crank it with a timing light hooked up, you can see if the timing is in range and you have a spark.

You can dribble a little gas into the carb to see if it is starving for fuel. You can also put your hand over the carb for a bit to richen it up. I prefer the dribble method as I have had one backfire when the timing was way off.

You need spark and fuel and air. Check compression. Check that the fuel is clean and making it to the carburetor by pulling the line off the carb and stick in a coke bottle, crank the engine and see if sufficient flow come out.

Rick

 

[Bondo]

Ayuh,.... Welcome Aboard,.... What vintage is this Merc 120,..??

If it's got Points ignition,.... Change 'n set the new Points,....

 

[Q8tMike]

Thank you Rick, I will try the gas trick in carb when I get back this weekend.

 

[Q8tMike]

Bondo not to sure of the motor year.
Boat is a 1969 Raider crestliner
I have some serial #s if that would help identify if needed

 

[Scott Danforth]

your boat is older than 1984 on the 4-bangers near 99.9% probability you have points (unless someone changed to pertronix).

get new points and condensor, change them, initial gap of 0.019 then using a dwell meter, set the dwell per the spec in the manual.

 

[Q8tMike]

Thanks guys, it is up and running. Just had to clean the carb and drop a little gas in and it's running great once woken up