johnson 28hp spl trouble

[thewillhartleys]

bought a new outboard for my aluminum boat. bought from a mechanic on craigslist who does boat repair full time now. first time taking the boat out, it was surging at wot but ran fine at half throttle. remembered that the last motor i had on before replacing was doing the same thing, so i assumed it was the fuel line system. replaced everything fuel line related. engine was doing the same thing except now, it bogs down completely when i open the throttle all the way. noticed the fuel filter looked almost empty while running. bulb is prettty stiff while running. before replacing the fuel lines, i assumed the fuel filter was bad so i ran the hose straight to the motor, bypassing the filter. ran totally fine, which led me to replace the whole fuel line system. im at a loss. i assume its running lean, with the throttle open so im not going to take it out again until issue is resolved. research is pointing me towards the direction of an issue with the high speed jet but i assume a carb rebuild is the first thing this mechanic did. also, the fuel tank becomes pressurized when not in use for a couple days so im assuming there isnt an air leak in the gas line. next step is to remove carb but hoping that im missing something small and an easy solution. any advice would be appreciated since i just bought the boat and just want to get out there and fish!!

 

[F_R]

Hm-m-m-m, what is the model number of your motor? The comments about the fuel filter are suspicious. How do you know it runs almost empty? Is it an after-market or accessory item? Is it adequate for the motor?

 

[thewillhartleys]

ill have to check on the model number. its pretty old so i lll have to do some searching. i can look at the fuel filter while riding. it looks like theres a tiny puddle of fuel in the bottom of the filter with a slight dripping into the filter from the side that feeds the fuel

 

[racerone]

Partially full filter sounds normal.-----Test run with another tank and hose.

 

[thewillhartleys]

would having the wrong low speed/idle air fuel ratio cause it to screw up at full throttle? or does that only affect the idle?