vacuum for fuel pressure regulater help
Thread Starter
Instructor
Joined: Jun 2004
Posts: 138
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From: ronkonlkoma ny
vacuum for fuel pressure regulater help
if the fuel pressure doesnt fluctuate...does that mean there is a vacuum problem??
i mean at idle,key on,revved,mid throttle
it stays exactly at 44 where its suppose to be..
i ask cause i have a rough idle and couldnt pinpoint.and i seen in a book its suppose to flux 3-10 pnds if you have maniflod vacuum??
i mean at idle,key on,revved,mid throttle
it stays exactly at 44 where its suppose to be..
i ask cause i have a rough idle and couldnt pinpoint.and i seen in a book its suppose to flux 3-10 pnds if you have maniflod vacuum??
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Yes pressure should rise noticibly when you rev the engine from idle or if you unplug the vacuum line from the plenum to the FPR.
When you unplug the vacuum line from the FPR is should have the same effect as going to WOT, i.e. fuel pressure should rise to the mid 40psi range.
If there is no fuel pressure change, you have a problem with the vacuum line or the FPR.
When you unplug the vacuum line from the FPR is should have the same effect as going to WOT, i.e. fuel pressure should rise to the mid 40psi range.
If there is no fuel pressure change, you have a problem with the vacuum line or the FPR.
Racer
Joined: Oct 2003
Posts: 273
Likes: 0
From: Midland Texas
If you are @ idle and diconnect the vacuum, you should see a rise in pressure. If you give it throttle, you lose vacuum also, but dont forget, you are pulsing the injectors faster at the same time, ie: delivering fuel. If you are maintaining 44 psi. with throttle input, your regulator is functioning. I would be looking for dribbling injectors, bad or out of tollerance IAC motor, vacuum leaks, plug wires, magnetic pick-up in the dist., leaking EGR, etc...A rough idle can be hard to find... 
