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I set my fuel pressure at 6 psi. When I start the truck, it immediately pulls 6 psi. I drove it today and got out at a stop sign to check my float level, and noticed the pressure was down to 4 psi. As I looked at it, the pressure went back up to 6 psi. I got out a few times and this happened each time. Any ideas on if this is normal or what might be causing it?
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The only thing I can think of is the pump not flowing enough? -
The issue I had a week ago was that the pressure was too high. I raised the float level a tiny bit and raised the pressure. I drove and it dropped again. It drops to 4 psi. I'm letting it cool off and will set the pressure to 6.5 psi and try again.Comment
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It would be interesting to see if the pressure drops by the same amount after raising the fuel pressure. Did you get a chance to look at the sight glass level before the pressure jumped back to 6 psi? How old is the fuel filter?Comment
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The front float level sits right at the bottom of the glass. The rear is a little lower. By the time the fuel pressure has dropped down to 4 psi the floats seems empty. I raised the front float level a tiny, but and that may have helped. I got the fuel pressure set on 6.5 psi with the new float level, and it held for the 100 yards I drove to park it for the night. I'll check it again today on a real ride.Comment
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I thought the fuel was supposed to be in the middle of the glass?Comment
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No: https://www.youtube.com/watch?v=8LNgwZe6r9s (Holley YouTube Tech Video)May God's grace bless you in the Lord Jesus Christ.
'92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, Eagle 3.470" forged steel crankshaft & H-beam rods, Wiseco 4.200" forged pistons, Trick Flow Twisted Wedge 11R 205 CNC Comp Ported heads, 12:1 compression ratio, 232°-244° duration/.623" lift/114° LSA H/R camshaft, Trick Flow R-Series FTI Comp Ported intake, BBK 80mm throttle body, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima 34/78 Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal Dual 12" HP 3168 CFM fans, Frostbite 3-core aluminum radiator, Pypes SS dual 2.5" exhaust, SS off-road X-pipe, SS shorty headers, OEM smog pump converted vacuum pump, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, highly modified Ford 4R70W transmission, FTI 9.5"/3000 stall/triple disc TCC, B&M Hammer shifter, Stifflers trans crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 3.73 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.Comment
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When I called Quick Fuel about my flooding issue, my floats were in the middle of the sight glass and they seemed happy with that. All the videos I saw say to have it at the bottom of the sight glass. Some of the carbs didn't have sight glasses they had plugs that you had to pull to check the level. So there would be no way to set the level in the middle of that type of plug. Mine is set near the bottom.Comment
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The carbs that I have with the old school level checker have to be set with the fuel just at the bottom of the threads. On the newer style sight glasses, that spot where the bottom of the threads would be lines up with about the middle of the sight glass. As long as the fuel level remains the same and the jets still have fuel covering them, you should be OK, although the mixture is affected by float level.Comment
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I'm still having issues guys. It idles great. Pressure is right where it should be. Drive just a couple of blocks and it's laboring to idle. Get out and look and it's down at 4 psi. Will idle itself back up to 6.5 psi after a minute. I walked back and removed the gas cap to insure it wasn't a tank vent issue. Made no difference. Fuel filter?Comment
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If that's correct SatherCS, then my floats are way too low. That WOULD lead to this type of issue too. So I'll raise em up to the halfway mark and give it another go.Comment
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I would think that if it continues to drop down in pressure while driving, then something is restricting flow enough that it can only maintain 4 psi under load. I would check the fuel filter and maybe brass filters that go into the fuel bowl inlets for any dirt, and if possible run the fuel line to a large bucket and check to see if any gunk comes out of the fuel line. You can run the fuel bowls lower than the middle, some people use that to fine tune the mixture. You just have to be careful not to go too low or you could run into fuel starvation issues under some conditions.Comment
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Fuel starvation I have for sure. The fuel lines are brand new. Filter changed today. I haven't considered the brass filters.Comment
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I've corrected this issue, and I can't remember how now.Comment
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