suburban tow truck fuel issue

Jack McCarthy · 10-18-2011, 07:59 PM

all right im tossing in the towel and begging someone smarter than i to assist with a 6 year old issue of losing fuel pressure ...

1990 suburban 1984 454 .040 reasonably fresh (has been out twice during this issue) , aluminum intake, RV cam, headers and a Qjet.
original tank mounted efi pump replaced with 3/8 copper line to bottom of tank
now have holley high perf mechanical pump
now have added carter in line small electric pump
fuel line is new from bottom of tank to carb, routed away from heat & insulated under hood
gas cap has hole drilled in it

has 7-8 lbs pressure when started ...
however after 1 hour or so of towing im running out of fuel at 2500rpm
if i stop i have 1-3lbs of pressure (guage inline under hood)
fuller tank seems to help but not 100%
temp of truck seems not to be an issue NEVER gets over 210 mostly 180

been 6 years, tanks been out 3 times, ran fuel line twice, two stock mechanical pumps plus holley and electric booster... im ready to put on areomotive 500gph and regulator or sell this thing while SCRAP is high !

help,
captain jack

10-18-2011, 07:59 PM	#1
Jack McCarthy VIP Member Join Date: Feb 2002 Location: lyndon ky. ... louisville area Posts: 1,322 Likes: 29 Liked 476 Times in 117 Posts	suburban tow truck fuel issue all right im tossing in the towel and begging someone smarter than i to assist with a 6 year old issue of losing fuel pressure ... 1990 suburban 1984 454 .040 reasonably fresh (has been out twice during this issue) , aluminum intake, RV cam, headers and a Qjet. original tank mounted efi pump replaced with 3/8 copper line to bottom of tank now have holley high perf mechanical pump now have added carter in line small electric pump fuel line is new from bottom of tank to carb, routed away from heat & insulated under hood gas cap has hole drilled in it has 7-8 lbs pressure when started ... however after 1 hour or so of towing im running out of fuel at 2500rpm if i stop i have 1-3lbs of pressure (guage inline under hood) fuller tank seems to help but not 100% temp of truck seems not to be an issue NEVER gets over 210 mostly 180 been 6 years, tanks been out 3 times, ran fuel line twice, two stock mechanical pumps plus holley and electric booster... im ready to put on areomotive 500gph and regulator or sell this thing while SCRAP is high ! help, captain jack __________________ Jack McCarthy 3609 STK "the Captain"