AQ1321A Bogging down and backfiring

"I have a 1986 AQ131A which I

"I have a 1986 AQ131A which I have done quite a bit of work to New timing belt, Tensionor,Electronic ignition,Cap,Plugs,Rewired all electrics in engine new breakers new relays new wires.I tested boat last year and it seemed to get to 4500 RPM.Then I winitrized full tank of gas put in Stabil,wrapped up all electical connections and routed them to a watertight box installed in engine compartment,retimed engine now the engine starts fine idles fine runs fine up to 2400 RPM then seems to lose power backfires and seems to be starving for gas it is much worse under a load cant figure out what happened between this year and last any ideas would be appreciated"

I would check a few things:

I would check a few things:

1) Make sure that the anti-syphon valve in the fuel tank is not stuck;

2) Check that the fuel filter (and also the fine filter inside the carb) are not clogged.

3) Check that the flame arrestor is clean.

4) Make sure the accelerator pump in the carb is not stuck.

How can I check anti-syphon va

How can I check anti-syphon valve as far as all else I installed new fuel filter and new flame arrestor and acclerator pump seems fine can see a steady flow of gas when I acclerate

"Try hooking-up a jerrycan wit

"Try hooking-up a jerrycan with fresh gas tot he suction side of the fuel pump and run the engine. If it doesn't bog anymore, find the anti-syphon valve (usually by the fuel tank) and either clear or replace it."

the anti-siphon valve gave me

the anti-siphon valve gave me all sorts of trouble last year. I replaced it and haven't had a problem since.

It should be on top of the gas tank. Its the metal piece that the fuel line attached to the fuel pump coming from the gas tank.