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Fuel Pressure: advice

  • Thread starter Thread starter OrangeMustangGt
  • Start date Start date Mar 3, 2004

OrangeMustangGt

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Mar 3, 2004
#1
  • Mar 3, 2004
  • #1
My friend has a 347 stroker motor, with afr heads, holly intake, now, he has 24lb injectors, and i was wondering a general fuel pressure to start out at. Thanks!
 

Jerry Leaming

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Nov 2, 2003
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Olympia Wa
Mar 3, 2004
#2
  • Mar 3, 2004
  • #2
Does it have a custom programed chip? I would guess 42psi would be a good place to start with out a chip . Alot of times with a custom chip the fuel pressure needs to be 38-39 psi.
Mine runs at 38psi but my chip compinsates for my all my upsized parts.
 

Rootus

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#3
  • Mar 3, 2004
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39 psi is stock, so that's where I'd start.
 

red94fiveo

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#4
  • Mar 3, 2004
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Is there any specific formula to figuring out FP, or is it just a tune it on your car and see sort of thing?
 

Rootus

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red94fiveo said:
Is there any specific formula to figuring out FP, or is it just a tune it on your car and see sort of thing?
Click to expand...
Fuel pressure is not something you generally need to adjust. The computer is constantly adjusting your tune based on feedback from the O2 sensors, and changing the fuel pressure is an extremely short-term solution. The primary reason for changing fuel pressure is to make smaller injectors act larger for applications which really should have larger injectors. This reduces the life of the smaller injectors, of course. It's best to get injectors properly sized for your application and then leave the fuel pressure stock.

Dave
 

red94fiveo

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Dave- My FP gauge will be here tomorrow and I'm going to try to elimanate that from my list of possible causes of my problem. Should I just set it at 39 and go from there? I talked to Paul, we have very similar combos, and he suggested 42 PSI, what do you think? Also, is this established with/without the vacuum line connected?
 

Rootus

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#7
  • Mar 4, 2004
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red94fiveo said:
Dave- My FP gauge will be here tomorrow and I'm going to try to elimanate that from my list of possible causes of my problem. Should I just set it at 39 and go from there? I talked to Paul, we have very similar combos, and he suggested 42 PSI, what do you think? Also, is this established with/without the vacuum line connected?
Click to expand...
The reason I suggest 39 is because that's what Ford specs it for stock. In reality it doesn't matter that much, it'll tune just fine at 42. When you set it, do it with the vacuum line disconnected (simulates WOT for the regulator).

Dave
 
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