Belt drives run at about 1/2 the RPM of a direct drive. This doubles the piston stroke and increases the suction at the inlet. Increased suction = increased hydrostatic lift. Check the pump specs, you'll see the difference for DD vs belt drive versions.
In some applications, this additional lift may make the difference between being able to use a non-pressure feed like a tank. Whether yours works or not depends on the lift height, seal condition, hose size, hose length, # of bends, degree of bends, air leakage, etc. This is why you have some people saying you cannot pull from a tank, while others say it works just fine.
This is not from me i copy an pasted this from a thread i read awhile back . im not ths smart lol
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The supply line on the tank may be lower than your pump, but you only need the water level in the tank to be higer than the inlet on the pump, then it should draw. Once it starts to draw you can even let the water level run below the supply on most pumps. Try it. There is a five inch difference between my tank outlet and my pump inlet. As long as I start out with the water level in the tank higer than the pump, then it works fine. My pump is also direct drive.