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confusion on fuel pressure

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Old Nov 11, 2011 | 01:54 PM
  #1  
smai555's Avatar
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confusion on fuel pressure

hey guys im having starting problems and i think i narrowed it down to fuel

im reading the FSM

i get about 34psi pre start and the FSM calls for 43psi

at idle im getting 32psi FSM calls for 34psi

testing the regulator it says as vacuum INcreases the pressure should DEcrease

i dont have a vacuum pump so i open the throttle from the TB creating vacuum and the pressure INcreases to about 35 psi

so its doing the opposite of what the FSM says it should does that sound right ? shouldnt it pressure increase as vacuum increase

any thoughts?
Old Nov 11, 2011 | 03:00 PM
  #2  
asand1's Avatar
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From: Reedsport, OR
Originally Posted by smai555
testing the regulator it says as vacuum INcreases the pressure should DEcrease
i dont have a vacuum pump so i open the throttle from the TB creating vacuum and the pressure INcreases to about 35 psi
Opening the throttle (acceleration) results in a drop in vacuum. Highest vacuum will be at idle, or coming down a hill with no throttle.

You are confusing manifold vacuum and venturi (TB) vacuum. FPR uses mani vacuum. Direct relation to engine load, not RPM.
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