First we'll need to know how many cc's your engine is but this:
http://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4DMUS_enUS221US222&q=Mikuni++DF52-73 is the model I use and they're usually big enough for most any kart application. I've been told the Walbro brand and round Mukini model pumps outlast the Mikuni square models.
Here's some good info:
http://www.mikuni.com/c-fuel_pumps.html
http://www.walbro.com/brochurefiles/3368441230-Pulse Pump final 2-9-05.pdf
Chances are your carbs needle and seat valves aren't designed to operate under fuel pressure and you may run into flooding issues. An easy way to remedy this is to install a fuel return line system to lower the pressure entering the carb. To do this you can either purchase a pulse pump with dual outlets or simply install a "T" or "Y" fitting between the pump and carb on single outlet pump models.
When I had to do this for my Honda carb I installed a Briggs inline fuel shut off valve
http://www.google.com/search?hl=en&...&q=Briggs+in-line+fuel+shut+off+valve&spell=1 in my return line so I could adjust the pressure level entering the carb by controlling how much fuel was returned to the tank.
If you experience flooding issues running a fuel pump, another option for you might be that Mukuni sells 2 different types of needle and seat valves for some of their carb models. (both gravity-feed and fuel pressure type)
As far as your pulse signal to operate the pump goes many motorcycle engines come equipped with a small vacuum fitting in the intake manifold. My Honda motor didn't so I drilled a hole and installed a 1/4" fitting into my intake.
These pulse pumps will also function off the pulse signal in the crank case of many small engines so that might be another option for you.
