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Thread: Erratic fuel pressure?

  1. #1

    Default Erratic fuel pressure?

    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?

  2. #2

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    The only thing I can think of is the pump not flowing enough?

  3. #3

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    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.

  4. #4

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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?

  5. #5

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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.

  6. #6

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    I thought the fuel was supposed to be in the middle of the glass?

  7. #7
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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.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  8. #8

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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.

  9. #9

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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.

  10. #10

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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?

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