3.0L OMC WOT Issues

[logran]

Greetings all! I'm new to this forum and have a couple of questions that I have developed after reading some of the related topics here.

First of all, my issue..well, my boats issues anyways
Basics: 1995 Four Winns 170 Freedom w/3.0L OMC 2bbl Holley carb (I appoligize for not having the engine # right now, Im at work) 17 pitch prop
Issues: Engine does not reach manufacturers recommende WOT range of 4200-4600 RPM. It only reaches about 3500 RPM and about 25MPH (seems accurate according to my calculations anyways). New plugs, light tan color after a few hours of running, good compression (160-175 in all cylinders), fuel lines from tank and tank both clean, new tank (squirrel infestation, chewed a hole right in it), fuel supply line and vent line new. good spark. Doesn't want to start after shutting off after running for a bit either. I read Don S's fuel system test and am going to go through it tonight. I would like to know 1. How to make a shunt jumper to check the timing and 2. if I have a filter inside the carb. It never has really hit the range for the proper RPM but it at least used to hit 4000RPM, now its down to 3500. Im thinking fuel system issues but would like to know the BEST place to start? Oh, also, its a little hard to start. Harder than Id expect with an electric choke anyways. My mechanical apptitude is good (former auto technician but my specialty was electrical), wrote service manuals for GM (again, electrical) and now vibration/durability testing of primarily automotive components.

Any help would be much appreciated. I will be glad to answer any questions to the best of my ability as well

 

[citation]

Re: 3.0L OMC WOT Issues

we had that same problem with our 3.0 OMC with a 2bbl rochester. i pulled the cover off when it was running and the fuel was just "bubbling" around the booster. it should of been an even spray. i rebuilt the carb at work and put her back on and it worked flawlessly. it had a lot of build up around the jets and the vents and the float was sticking. i soaked the whole carb in solvent for three hours and put her back together. the reason the cut out is there isnt enough fuel to supply the extra air coming in at WOT. our's would hit 3K rpms and you could keep moving the stick but nothing else. it would also be hard to start after running as the hot engine just evaporates the little fuel that's entering the intake. when we found the problem, we'd just hit the throttle a few times without the motor started to get some fuel into the manifold and it started every time. of course now it works like a charm after the rebuild... so well the ball gears are now the next problem

i hope this helps