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89 4.3 omc not running

Ncycenas

New member
Hi all, I’m new here and to the boat world in general. I recently picked up an 89 Four Winn with a 4.3 omc in it as a project to challenge myself. The boat has been sitting for 5-6 years and is not running. I replace the starter, verified I’m getting fuel and spark with no luck. Not really sure what to look at next.

any help/advice would be appreciated!
 
are you getting fuel down the throat of the carb?... if this isnt happening, it wont run.. you can pour a couple tablespoons of fresh fuel down the carb, which if its getting good blue spark, it should fire and attempt to run until it burns off the gas that was poured in to it..... be careful with this procedure, as sometimes you can get a back fire which can catch the gas container on fire, and then the boat.....
I use a squirt bottle for this, NOT a spray bottle, but a bottle with a small hole in the lid that can be squeezed to dispense the liquid.... and KEEP IT AWAY from the engine while cranking....

if anyone has worked on the boat without it ever running again, you need to check and see that the plug wires are in the correct order from the cap positions to the correct cylinders.. and you should see blue spark at the spark plug when checked with the plug out of the engine, inserted into the wire, with the metal spark plug body held firmly against the engine block plug...... while cranking. if its yellow/orange spark, then something isnt adjusted right and it may not be firing under pressure in the cylinder...

its possible that if someone worked on the boat in an attempt to make it run (without knowing what they were doing) the timing could be off also....
 
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are you getting fuel down the throat of the carb?... if this isnt happening, it wont run.. you can pour a couple tablespoons of fresh fuel down the carb, which if its getting good blue spark, it should fire and attempt to run until it burns off the gas that was poured in to it..... be careful with this procedure, as sometimes you can get a back fire which can catch the gas container on fire, and then the boat.....
I use a squirt bottle for this, NOT a spray bottle, but a bottle with a small hole in the lid that can be squeezed to dispense the liquid.... and KEEP IT AWAY from the engine while cranking....

if anyone has worked on the boat without it ever running again, you need to check and see that the plug wires are in the correct order from the cap positions to the correct cylinders.. and you should see blue spark at the spark plug when checked with the plug out of the engine, inserted into the wire, with the metal spark plug body held firmly against the engine block plug...... while cranking. if its yellow/orange spark, then something isnt adjusted right and it may not be firing under pressure in the cylinder...

its possible that if someone worked on the boat in an attempt to make it run (without knowing what they were doing) the timing could be off also....

thanks for the reply

I tried fuel in the carb with no luck. Checked plugs with an in line tester. According to the previous owner he had it winterized and hasn’t touched it for 5-6 years. So I believe all the wires are where they should be but will double check

I went out and grabbed a compression tester and am going to check compression and each plug visually. Hopefully the compression is good!
 
the inline spark testers are questionable... i dont use them because there is a more dependable way to check for a good spark...

when an engine has been winterized, the plugs can get fouled from a heavy dose of fogging oil, and may need to be replaced... especially after setting 5-6 years.... and its usual for someone who says the boat has been setting 5-6 years to actually mean 8-10 years.... because time has a way of getting away from us.
 
the inline spark testers are questionable... i dont use them because there is a more dependable way to check for a good spark...

when an engine has been winterized, the plugs can get fouled from a heavy dose of fogging oil, and may need to be replaced... especially after setting 5-6 years.... and its usual for someone who says the boat has been setting 5-6 years to actually mean 8-10 years.... because time has a way of getting away from us.



Checked compression it was about 120 in all cylinders. Swapped all the plugs and it kicked briefly. Going to swap out the fuel filters and hope for the best
 
Checked compression it was about 120 in all cylinders. Swapped all the plugs and it kicked briefly. Going to swap out the fuel filters and hope for the best

try more fuel in the throat of the carb... you may not be getting enough.... if the carb isnt delivering fuel as it should, you have little chance of flooding it...
 
try more fuel in the throat of the carb... you may not be getting enough.... if the carb isnt delivering fuel as it should, you have little chance of flooding it...


swapped out the fuel filter at the carb and got it to run for 1-2 sec with throttle. Going to pull the carb and give it a good cleaning tonight.

if all parts are in good shape I will hopefully get it back on tomorrow after work.
 
Gave the carb a good cleaning. All parts looked like they were in good shape. Reinstalled and still nothing. Will only run 1-2 sec with throttle.

Could the fuel pump not be giving enough pressure? It’s a mechanical pump on the block.

im running out of ideas here.
 
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