Fuel and carby problem on a Sherpa

[poprock]

Hi, sorry for the off track but too old n silly to post on fb.
Changed fuel filter on my 85 sherpa, now very noisy and runs nonstop.The float is overpowered by the pressure and the fuel flow in the primary is hose like.
So i ebayed and bought a datsun sonny carby $88 ( yeah, i know its twice the capacity, but it should only draw according to vacuum ) and lo, it does the same as the ek42 carb, running but not flooding, just fouling the plugs.
Took the filter and pump off again ,refitted all fittings to suby manual. Do have a spare pump but seized after 6 years idle. Any polite suggestions or similar experiences ?