Can I prove the fuel pump by bypassing it and having a passenger pump the primer bulb like mad? I don't really want to spend on all the bits to rebuild the carbs without a bit more evidence that it is really them. I tried having a passenger pump the bulb while the fuel pump was inline without any success.
It might help but I'd connect the in & out of the pump together as the usual fault is a hole in the diaphragm which allows excess fuel to be sucked into the cylinder that the pump takes its pulses off. Pumping the primer in this instance would probably make things worse
If you just leave the pump ends open you could possibly suck air & create a different fault .I'd link a short hose from inlet to outlet then try the hand pump method
Usually you can get away without buying any parts to rebuild the carbs if your care full with the gaskets etc you can usually reuse the old ones
Usual problem is just muck or solidified fuel in the jets.a damn good clean usually sorts them without any new parts
As a note the carbs have enough fuel in them to keep it running for a little while even if the fuel line is disconnected. With the motor off and pumping the fuel bulb, do it get hard? How does the motor start after doing so?
Depending on age of the motor, it might be a good idea to replace the fuel pump as they do fail. Inspection of the diaphragm is pretty easy.
I would strongly recommend a water separating fuel filter if you don't already have one.
