43 surging at WOT perfect otherwise

"1988 2056 limited renken
4.3

"1988 2056 limited renken
4.3l v6 4bbl carb
50 hrs on new engine
19p prop, usual WOT 4700rpm @ 44mph

Boat has run excellent all season, everything has been flawless. Yesterday i was running about 25 mph at 3300 or so RPM and punched it as another boat approached and immediately it stumbled so i drew back the throttle. The boat recovered with no problem and then i tried it again. It surges anytime i pass 3500 or so RPM or as soon as the back barrels start to open. After looking at the back barrels i noticed the choke was stuck open. after flipping it back down the boat ran great again. Today after 4 hrs or so the same thing happened. This time after checking the carb, everything seemed fine. In fact i watched as the boat was accelerating and the choke/butterfly seemed to opperate properly. Out of gear it has no problem reving or idling. Was told that it could be water in the gas, debris in the carb, or the ignition coil. Any other suggestions before i take it to the mechanic to have the carb rebuilt? Otherwise there are no other problems with lack of power. It planes just fine so long as i dont push it past 3500 or so.
Thank you in advance"

did you change the plug wires

did you change the plug wires when you did the rebuild? if not check it at night and see if there is an arc coming frim one of the wires to the block. or distrib may have a crack in it. Poss the timing is a little off.

good luck

"When you say the choke is stu

"When you say the choke is stuck open, I am guessing that means the secondary butterfly is hanging open. There are some needle valves attached to the secondary butterfly. If it is stickino open then alot of fuek is being dumped into the engine. Withe the engine off move the butterfly valve by hand and see if anything is binding. You may have to take off the vacuum pull off to move the butterfly freely. Also, check the linkage from the vacuum pull off to the secondary butterfly. When the pull off loses vacuum at wide open throttle, the secondary valve opens. Good luck"

"Check the fuel filters. There

"Check the fuel filters. There could be one in the carb where the fuel line connects.(inside the connection) Careful here,it is easy to strip these threads and to loose or damage the gasket. The fuel pump could be getting weak. This sounds like it is running out of fuel at wot. The surging sounds like the fuel pump is not keeping up or the line is restricted. If you think of how the pump works this will make sense. You will only have this under load since the engine doesn't use enough fuel in netural to run the fuel out of the float bowl. Hope you find it."

"Yes, the wires, rotor, cap, e

"Yes, the wires, rotor, cap, etc. were replaced with rebuild. Also a new fuel pump was put in at the same time. I will look into the last two suggestions this weekend (boat is kept out of town at the lake). And yes, the first time the secondary butterfly was stuck open, and that problem was corrected. My mechanic seems to think its water in the carb. He wants to rebuild the carb this weekend (free labor so I guess i'll have him do it anyways). I'll post after the weekend to let you know what happens. Thanks again"

"That 'choke' is suppo

"That 'choke' is supposed to open and close with the throttle, as you have discovered. I suspect rust has gotten to its linkage. Suggest carb cleaning.

Jeff"