Engine stall on WOT from slow speed
 

I have been struggling to get my engine to right for two seasons now so I thought I would throw it out to the forum and see what everyone thinks.

1996 190 Shabah
4.3LX Thunderbolt IV with Weber 9600 4 Barrel Carb + K&N air filter
21", 3 blade SS prop
Smart Tabs

My boat sat for a couple years without being put in the water. Beginning of last summer I got it running but it never ran quite right. Had to change the fuel filter and fix the timing. Over the winter I removed the carb and rebuilt using the Edelbock rebuild kit. I found that one of the float bowls was filled with a very fine dust (light brown) that was clearly affecting flow through both jets on that side. I am not sure why, but the other side of the carb was clean. FYI, I have very little carb experience. This was the first time have ever worked on a carburetor.

Installed the carb in the spring and the boat fired up right away and ran decent. Did some adjusting to the idle screws and then just left it alone up to this point to see how it settled in.

The current situation is that the engine will stall if throttle is open all the way from a slow speed (off plane). The engine seems to rev up and accelerate much better between 50%-75% throttle. I went out early in the morning last weekend and after getting on plane and cruising at about 35mph, I opened up to WOT and the boat ran very nicely...48mph GPS @ 4950rpm.

I changed out the fuel filter the next day and it did not appear to change the issue.

Any suggestions on the next troubleshooting steps to take?

Engine stall on WOT from slow speed
 

I would check to make sure the floats are adjusted to specs as well i would also double check the jets for any clogs... Its sounds like to me that when you go WOT, there isn't enough fuel to keep it running. Just a thought.

Re: Engine stall on WOT from slow speed
 

I adjusted the floats when I rebuilt it but I will double check them. I am planning to pull the top of the carb off next time I am down at the lake to inspect the jets and float setting. Unfortunately, the boat stays at the lake 250 miles away so it's hard to work and troubleshoot the issues. I also plan to check the accelerator pump to make sure it's not clogged.