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$8D fuel pressure variation

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Old Jan 15, 2017 | 08:36 PM
  #1  
Dr.E's Avatar
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Car: 5500lb Brick
Engine: Gen 1 SBC 383 Hyd Roller cam
Transmission: TH 400
Axle/Gears: 4.10 35in tires
$8D fuel pressure variation

Is it normal to have a lower fuel pressure at hot idle vs cold idle?
The fuel pressure gauge reads about 3lbs lower after a logging session.
What things should I check if not normal?
Walbro 255LPH Aeromotive AFPR P/N13109.
Thanks!
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Old Jan 16, 2017 | 11:13 AM
  #2  
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From: Chasing Electrons
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Engine: check
Transmission: check
Re: $8D fuel pressure variation

If the gauge is liquid filled that will do it. As the gauge heats up the liquid expands and puts additional pressure on the Bourdon tube.

An aluminum FPR can expand from the heat and change the fuel pressure. I generally do the final fuel pressure setting on a warm engine.

RBob.
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Old Jan 16, 2017 | 03:26 PM
  #3  
Dr.E's Avatar
Thread Starter
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Joined: Nov 2007
Posts: 69
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Car: 5500lb Brick
Engine: Gen 1 SBC 383 Hyd Roller cam
Transmission: TH 400
Axle/Gears: 4.10 35in tires
Re: $8D fuel pressure variation

Thanks RBob!
All the more reason to have as accurate a tune as possible.
I suspect electronic FPR with voltage compensation tables in the future?
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