FUEL PSI AND LINE SIZE
#1
Senior Member
DYNO OPERATOR
Thread Starter
Join Date: Apr 2008
Posts: 496
FUEL PSI AND LINE SIZE
I HAVE HOLLEY BLUE ELECTRIC FUEL PUMP AND THERE REGULATOR WHILE MY ENGINE IS RUNNING THE GAUGE REDS 6 TO 6.5 PSI I ADJUSTED IT TO 7 AND A BIT LATER IT FALL'S BACK TO 6 IS SOMETHING WRONG?I HAVE 8 AN FUEL LINE FROM THE TANK TO THE CARB IS THAT OK OR SHOULD I BE USEING SMALLER LINE FROM THE REGULATOR TO THE CARB?
#2
Senior Member
RACING JUNKIE
Join Date: May 2003
Location: Coldwater, MI
Posts: 2,998
Re: FUEL PSI AND LINE SIZE
Originally Posted by JEFF69Z28
I HAVE HOLLEY BLUE ELECTRIC FUEL PUMP AND THERE REGULATOR WHILE MY ENGINE IS RUNNING THE GAUGE REDS 6 TO 6.5 PSI I ADJUSTED IT TO 7 AND A BIT LATER IT FALL'S BACK TO 6 IS SOMETHING WRONG?I HAVE 8 AN FUEL LINE FROM THE TANK TO THE CARB IS THAT OK OR SHOULD I BE USEING SMALLER LINE FROM THE REGULATOR TO THE CARB?
#3
Senior Member
DYNO OPERATOR
Join Date: Apr 2008
Posts: 504
Hello Holly blue
Also in addition to the heat issue possibility, this is the reason that regulators are so expensive that work well, meaning repeating there set pressures. The fuel pump has a pressure regulating spring in it and could also be causing your fluctuation in pressure. The holley blue comes with a regulator thrown in the deal when you buy them from some sources, this may give you some idea of it's relative value and reliability. That pump will not ever out run your #8 line. More expensive pumps have closer machine clearances and perform more smoothly and reliably as far as pressure consistency is concerned. Running less than 7 psi is recommended in most all gasoline applications. If the pressure drops more than 1.5 PSI from your set pressure the fuel level in the bowl will fluctuate too much give constant fuel ratios and needs to be corrected. Your complaint is not new or unique, but if you minimize the pressure fluctuations your car will perform more consistently and probably last longer too.
Bruce
Bruce
#4
Senior Member
DYNO OPERATOR
Thread Starter
Join Date: Apr 2008
Posts: 496
it falls back after running awhile and then i cant get it back to 7 psi.the gauge is liquid filled and a jegs brand and is about 2-3 inches from the intake.i guess i shouldnt have the regulator mounted on a bracket i made bolted to the head.
#5
Senior Member
RACING JUNKIE
Join Date: Jun 2003
Location: Hobbs, NM
Posts: 842
The Holley blue doesn't have a return, therefore it will loadup and has trouble getting going again when you need it. I wouldn't run a Holley blue in a rear tank application. Money well spent to get a Magna fuel pump with return and a Magna fuel regulator. You problems will go away. JMO
#6
Junior Member
JOURNEYMAN
Join Date: Aug 2006
Posts: 28
Originally Posted by dparker
The Holley blue doesn't have a return, therefore it will loadup and has trouble getting going again when you need it. I wouldn't run a Holley blue in a rear tank application. Money well spent to get a Magna fuel pump with return and a Magna fuel regulator. You problems will go away. JMO
#7
Senior Member
MASTER BUILDER
Join Date: Dec 2005
Location: berea,ky
Posts: 184
I have a Jegs liquid filled fuel pressure gauge mounted under the hood and when it gets hot the gauge shows a lower pressure,sometimes real low depending on how much heat.Anyway i borrowed a non liquid filled Stewart Warner pressure gauge and set my fuel pressure off of that and really don't even worry with mine anymore.Something for you to check out,take some ice in a bag and put it on your pressure gauge and let it cool for a little bit and watch the gauge change.