The last couple of times I have been out, my motor bogs down between 3000 & 4000 rpm. When it starts to bog down if I put it to WOT it opens up to 5400 without a hitch & will run at 5000 rpm no problem. If I leave it between 3000 & 4000 sometimes it will even quit altogether but if I pump the primer bulb it will keep going. It seems to start and idle fine but every now and then will quit at idle.
Normally I would go to "fuel pump" but the carbs and fuel pump were rebuilt this last winter - may still be that but looking for more ideas before I do the rebuild again.
So here is what I am seeing and what I have done so far:
I attached a pipe to the fuel tank pickup point and can suck and blow on that no problem (so no blockage at the tank). The primer bulb does not get pinched at any speed but does empty itself at the 3000 - 4000 rpm (if I pump the bulb it will keep going). I connected the motor to a portable tank with clean gas & there is no difference to the motor's behavior. I ran iso-heet through the portable tank in case there was water in the carbs - no difference. I replaced the in-line fuel filter on the motor.
Replaced fuel hose and primer bulb - no difference.
I am thinking a small air leak between the fuel hose connector and the fuel pump or maybe a hose that pinches at higher vaccum?
Like I said could be the fuel pump but I am looking for other possibilities. Any help would be most appreciated. I am pretty good with a wrench but this one has me stumped.
Normally I would go to "fuel pump" but the carbs and fuel pump were rebuilt this last winter - may still be that but looking for more ideas before I do the rebuild again.
So here is what I am seeing and what I have done so far:
I attached a pipe to the fuel tank pickup point and can suck and blow on that no problem (so no blockage at the tank). The primer bulb does not get pinched at any speed but does empty itself at the 3000 - 4000 rpm (if I pump the bulb it will keep going). I connected the motor to a portable tank with clean gas & there is no difference to the motor's behavior. I ran iso-heet through the portable tank in case there was water in the carbs - no difference. I replaced the in-line fuel filter on the motor.
Replaced fuel hose and primer bulb - no difference.
I am thinking a small air leak between the fuel hose connector and the fuel pump or maybe a hose that pinches at higher vaccum?
Like I said could be the fuel pump but I am looking for other possibilities. Any help would be most appreciated. I am pretty good with a wrench but this one has me stumped.