Modifying a fuel sending unit question

[ncmiller1]

Has anyone had to modify their fuel sending unit? I just installed a 3/8" feed with ¼" vapor return fuel sender to accommodate a new Mallory electric fuel pump with a return style regulator (#4142) and my fuel pressure is off the charts.  I installed a new 3/8" fuel line from tank to carb and tried using the existing 5/16" line as the return and pressure was over 18psi with the regulator on full bypass.  So I then replaced the 5/16" line with another 3/8" line and the pressure is still 18psi, when the Mallory instructions say it should be less that 3psi on full bypass.  I tested the return line off the regulator with just a 3' piece of 3/8" hose into a bucket and pressure was at 2.5psi which leads me to believe it isn't the regulator, but that ¼" return line on the fuel sender which is acting as a flow restrictor.   
This is hooked up to an Edelbrock carb so I definitely need pressure to be much lower.

So my questions are:
Do they make a fuel sender with a 3/8" feed and a 3/8" return? 
Has anyone had to modify the one they have by drilling out the ¼" line and brazing in a 3/8" barb?
How difficult is it to braze in that new tube? (obviously with the sender removed from the tank)

Thanks for any help!

[Cooter]

Have had some luck with a buddies car. (Upgraded BEFORE you could buy a 3/8" pick up), and found if you do not move the fuel in the return AWAY from spraying directly on the sender unit pick up, it will cause cavitation of the pump.(Bubbles). It DID work though.

[cdr]

you are going to have to modify the return on the sender to at least 5/16

[ncmiller1]

Cooter:

Thanks for the reply and that makes sense.  Unfortunately I dont think that is my problem because the return line on the sender takes a 90 degree turn once it enters the tank and shoots out toward the side of the tank and shouldn't cause cavitation (hopefully).

[cdr]

take the sender to a radiator repair shop they can solder a 5/16 tube .

[tan top]

  silly question i know  ,  but cant you adjust fuel pressure at the pump , some pumps you can  , also  some electric pumps  you dont even need a regulator  , although  good idea to have a return line !!
edelbrock carbs are very pressure sensitive  , 5.5 to 6 psi max at the carb  ,  have 6.5psi with mine , but have got a  metered return line , back to tank.

[ncmiller1]

cdr: thanks for the advice, that seems like the best option so far.

tan top:  the fuel pump does have a pressure adjustment, but the main reason I upgraded to an electric pump with a return style regulator was to get constant fuel circulation to see if it would cure the evasive vapor lock issue, which I sadly suffer from.  In the end, if the sender modification doesn't work out then I will start dialing down the pressure at the pump. 

Thanks for the suggestions!

[tan top]

cdr: thanks for the advice, that seems like the best option so far.

tan top:  the fuel pump does have a pressure adjustment, but the main reason I upgraded to an electric pump with a return style regulator was to get constant fuel circulation to see if it would cure the evasive vapor lock issue, which I sadly suffer from.  In the end, if the sender modification doesn't work out then I will start dialing down the pressure at the pump. 

Thanks for the suggestions!

yeah i see now  ,  i done the constant  fuel circulation thing through the carb ,  cause i was having fuel boiling hot idleing problems ,