fuel pump

[Goose_ss4]

i have recently replaced the lift pump on my 93 f-250 7.3l turbo diesel idi, and moved the fuel filter back by the tank to make room for the intercooler piping. my problem is that the hard line coming from the lift pump to the injection pump switches sizes at the filter housing. now that i don't have that option there, i tried to put a rubber fuel injection hose from one to the other. super tight fit on the lift pump, but loose on the injection pump end. i think i can get around this problem, but my question is it possible to run a mechanical pump and an electric aftermarket one together.
i have always had trouble with air in the tank when you stand on it at a quarter or less tank of fuel. i am also led to belive that i loose a lot of pressure under full throttle.
i want to run the mechanical lift pump into a system where the electric one backs it up, so that check valves would prevent fuel from back flowing into either of the pumps. this way always have full pressure.
was thinking an airdog platinum fuel air/water separator.
what do guys think?

 

[RLDSL]

The air at quarter tank is a broken off fuel pickup in the tank, do a search, this is well covered, until fixed, keep tank full above 1/4, problem solved.
Air dog is TOTALLY USELESS waste of money for our trucks!
Modern electronic injected diesels fire electroniclly 5-8 or more times per stroke and when teh slightes bit of air gets in teh fuel, teh injectors ccavitate and just sit there and pump air, that is what an Air Dog is for. We have mechanical injection systems that fire a lowly one time per stroke, there is no problem with cavitation in the fuel system. Just keep a good filter on your engine and you are good to go