GX390 on a pressure washer will not stay running after fuel pump install

Hey all,

Picked up a brand new GX390 that belt drives a nice 5.5gpm 3k PSI comet presser washer pump. Made custom feet for it, and mounted it to a soft wash skid. The oem fuel tank was super hard to access to fill up, so I pulled the tank, and bought a vacuum fuel pump, and mounted it where the oem tank was.

Bought a marine style gas can, connector end for said can an an inline priming bulb and a carb spacer with a vac port.

I can give the prime bulb a couple pumps, choke it and it cracks right off and runs just fine. But it suddenly dies out of nowhere with often no warning and will typically only restart on choke. I thought it was a fuel issue, but each time it dies the inline fuel filter bulb is totally full of fuel. Only way I could get it to run consistently was to elevate the tank well above the engine, which is entirely defeating the purpose of the fuel pump.

I’m of the understanding that these vacuum fuel pumps should be able to pull fuel with the tank even a couple of feet below the engine and pump itself, but maybe I’m wrong.

I’m sure I’m missing something simple here, but this is really kind of driving me nuts at this point and I am entirely open to being schooled here.

Appreciate any insight or advice!