Cant keep fuel Pressure

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blownnalky1
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Joined: Tue May 26, 2009 11:44 pm

Cant keep fuel Pressure

Postby blownnalky1 » Wed May 27, 2009 12:27 am

Ok anyone can help please do, i went in and changed my fuel system around, i put in a fuel cell with a rear sump, The pump is mounted right next to the fuel cell about 6" below it with about 16" of line from the cell to the pump, i plumbed it with #8 from the tank to the electric mallory 140 fuel pump all the way up thru a k&n racing fuel filter, to a mallory 3 port fuel regulator with a return, the return line is the factory 3/8 hard line. just after the regulator i have a inline fuel gauge, and i also have a second gauge that runs inside the car so i can see the fuel pressure as i run the car. The fuel system sizes down to a #6 fuel log that feeds a holley performance series 750cfm manual choke carburator. which has mechanical sec. I do have both the front and rear power valves blocked off, Its feeding a 383 stroker with aluminum heads bowtie high rise intake and dyno at 512hp and 512 ft lbs torque and a turbo 350 trans. with a 5000 stall. peak horsepower is at 6200 rpm.

here is the problem i can set the fuel pressure at 8psi as soon as i hit the gas it drops to 3psi, then if i step into it hard it drops to 0 psi. it will pull hard thru 2nd gear then lays over like it has absolutely no fuel. i can pump the gas and i get nothing, if i let it idle for about 15 seconds while i coast to slow down, the fuel pressure comes back up. I have tried to eleminate the return line, and at idol im sitting at 18psi as soon as i hit the gas it drops to 9psi, i step into it in 2nd gear and it drops to 0psi again. laying over at about 4000rpm in 3rd gear.

does anyone have any idea what the problem could be? im also in denver at 5800ft. Any help would be greatly appreciated.
Scott

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draglist
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Postby draglist » Wed May 27, 2009 1:10 am

Welcome, Scott, and good luck... some tech savvy guys in here. bp
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Eric David Bru
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Postby Eric David Bru » Wed May 27, 2009 8:28 pm

How big of a tank vent?

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blownnalky1
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Joined: Tue May 26, 2009 11:44 pm

Postby blownnalky1 » Wed May 27, 2009 9:05 pm

im running a #8 size vent. and i vent it out the bottom of the trunk outside the car.
Scott

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Leon
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Postby Leon » Wed May 27, 2009 9:52 pm

No 1 the pump isnt big enough.It needs at least a BG280 and it needs -8 inlet lines.Id want -10 from the pump and -8 return so it will keep the fuel flowing so it wont get hot dead heading to the pump. The filter is also a restriction as is the mallory regulator. Get a good regulator that isnt so restrictive. Havent kept up with the latest,but their are others besides bg,altho i never had a prob with em. What jetting? At that DA if it isnt rich,at sea level it wont even run.lol


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