PKRWUD |
07-23-2003 05:51 AM |
Quote:
Originally posted by Nixon1
Dont mean to hijack this post..just a quick question. What does pulling the vacuum line off do to your fuel pressure reading? I checked mine a while back at idle with the line connected and got 38-40. Does it go up with the vacuum disconnected?
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The engine requires more fuel at WOT, so the engineers had to figure out a way of adding fuel then, but in a way that would not effect emissions, drivability, and economy at other times. The answer was to make the spring that moves the diaphram inside the regulator a little bit stronger, so that uncontrolled, the fuel pressure would be higher than normal, to satisfy the needs at WOT. They then attached a vacuum port to the back side of the diaphram, so that when there was engine vacuum, it would slightly overpower some of the spring tension, reducing the fuel pressure. Since the manifold vacuum drops as the throttle opens, this was the perfect answer. At idle, when the pressure should be the lowest, there is full manifold vacuum at the regulator, so the pressure is at it's lowest. As the throttle opens, the manifold vacuum drops, and the spring overpowers the vacuum, opening the diaphram more and more, until finally, at WOT, when there is little to no manifold vacuum, the spring has opened to it's fullest, giving you it's maximum fuel pressure. Since an engines vacuum at idle can vary, but it is always zero at first when you go to WOT, fuel pressure is usually checked with the vacuum line disconnected, representing WOT.
Get it?
:)
Take care,
~Chris
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