I was wanting to know, if anybody knows for sure what the pumps in our trucks are rated at and if I want to increase the volume, what size inline fuel pump I should use as not to create a problem with the in tank units. Need to supply more volume for my Mods so I am not running lean. Walbro 190LPH or ?????

Thanks,

 

What year truck?
One tank or two?
Two pump system or three?

It makes a difference

 

1994 F150 5L XLT automatic, dual fuel tanks and a two pump system

 

Your stock pumps are rated at 105 LPH @ 39 PSI. That's enough to support about 280 HP. AFAIK no one has found a viable substitution for dual tank trucks. The stock pumps include a pilot operated check valve in the return line. When the pump is running, it holds the valve open and allows fuel to return to that tank. to my knowledge, none of the Mustang based aftermarket pumps include this feature. If the Lightnings used bigger pumps (which I do not know) then perhaps a Lightning pump would be of use.

The thruput of the stock pumps will increase at lower pressures. It is just possible that by installing a 155 LPH inline pump you would reduce the discharge pressure on the in-tank pumps enough that they could keep up, but that is only a guess on my part. The old 3 pump systems used low pressure in-tank pumps rated at about 170 LPH, just enough to support a 155 inline.

You probably have to forget about a 190 or larger unless you're willing to lose the second tank.