wont start after sitting for 30-60 mins

[jetman42485]

i have a 1989 omc 4.3 with auto choke. 2 barrel carb. it wont do this with the muffs witch get very irritating. but it will fire up right away cold.....runs perfect, then once i shut it off and let it sit for 30-60 mins maybe little more it wont fire up. it floods its self out. if i shut it off and turn it over within 15 min it fires up instantly....any ideas? i had the carb rebuilt.....with all new parts. only thing i can think it the chokes turning on and flooding it. but i dont know......any help would be great. thanks

 

[Howard Sterndrive]

Re: wont start after sitting for 30-60 mins

I wouldn't assume it's flooding unless you smell gas or see a closed choke (easy to eyeball that). Next time it won't start, pull the spark plugs (especially rear two) and look for gas or water droplets on them.
If an exhaust manifold or riser is failing it will put water in the cylinders which quenches any chance of combustion.

If you spread the water evenly on all 6 cylinders it may go, but In the lake the rear of the boat sits lower.

After that a compression test would be my next step, and then on to the ignition system. The back pressure of a submerged exhaust can prevent a tired engine from starting if compression is low.

 

[jetman42485]

Re: wont start after sitting for 30-60 mins

When it won't start in the lake,I pull the passenger side front spark plug,turn it over couple reps and it fires. So I put the plug back in and she runs like a top. Does that sound like the exhaust manifold?

 

[jetman42485]

Re: wont start after sitting for 30-60 mins

Could it be just the gasket?

 

[talies13]

Re: wont start after sitting for 30-60 mins

mine was doing the same thing. when i run it and sit for 10 to 15 min it wont start in neutral. so i pull the shifter into neutral and give it some gas and it starts right up . its like the choke is not opening properly. but it starts every time when i pull the shifter into neutral and give it gas. i would like to fix mine properly but this seam to work to. i thought my carb was flooding to but it wasnt. its a choke issue im preaty sure

 

[HCMQA]

Re: wont start after sitting for 30-60 mins

Mine did the same thing. It turned out to be the carb. Rebuilt it and all is well.
How long ago was yours rebuilt?

 

[jetman42485]

Re: wont start after sitting for 30-60 mins

I just had it rebuilt this spring