One trick I used on my Truck motor was to hook up clear plastic line to the hose end and run it to a VP fuel can for fuel collection. When I ran the fuel pump with 12 volts and opened the fuel solenoid for a spray I saw bubbles in the fuel while the fuel was traveling to the collection jug. Mind you I did have a loop in the line to assist with purging the air out as the fuel flowed through. Seeing the air bubbles meant the fuel pump was cavitating in the fuel tank. I dropped the tank, sure enough, the pump was moving the fuel out of the factory built in fuel reservoir that the pump sits inside when installed into the tank faster that the return line and small fill hole could allow fuel to fill it up and submerge the pump.

So I cut more fill holes into the reservoir and cut down the height of the reservoir. Since that mod, after checking, there have been no more bubbles are lean readings from the Wide-band O2 gauge. Hope that helps a bit...

Shawn