OMC 4.3 cutting out

[Crash01]

Ok here is my dilemma I have a 1987 170 horizon fourwinns boat. I had the motor rebuilt because block was cracked. Put new carb on motor and also new coil. My problem is that when i hook up water hose to outdrive and run boat the throttle will power up to top end with no problem, but now when i put it in the lake the throttle will go up till little over half way and completely cut out and try to come back. If i bring throttle back down to half way it will go back to running fine. I think its a firing problem due to the fact it only does it when its under a load but do you guys have any idea.

Thanks,
Crash1

 

[Don S]

Re: OMC 4.3 cutting out

A test of any kind without a load means nothing, it's a non test.
If you pull all the plug wires off one side, it will go to 10,000 rpm in neutral.
How does it idle? will it idle at say 650 rpms? Is it smooth?

 

[89 VIP Valiant]

Re: OMC 4.3 cutting out

Did you set the timing by ear, or did you use a light and set it to the manufacturer specs?

 

[Bondo]

Re: OMC 4.3 cutting out

I think its a firing problem due to the fact it only does it when its under a load but do you guys have any idea.

Ayuh,... It's a Fuel Delivery Issue,... Change the Fuel Filters,...
Or the tank is boogered up,...
Or the Carb needs rebuilding,...
Or,.....