[V8] MPG Semi-Conclusion?

Jason Wilkerson wilke_jb at yahoo.com
Sat Feb 10 22:29:42 EST 2007

Ok, Tonight I worked on the bad MPG thing again.  What I found was not
what I expected.  I was taking stuff apart to get the intake manifold off
and I pulled the two vaccum hoses from the front of the throttle part - on
a whim I traced these out to a valve located on the pass side fender,
directly behind the coolant expansion tank.  I saw that it was diaphram
type valve and I assume that it is the evap valve, as there is a hose
coming to it from the 'out' side of the carbon canister.  There is also a
set of wires going to this valve for either some type of actuation or
sensing - I'm not sure which.  I tried blowing/sucking on the small hose
that would operate the diapram to allow the stored gasoline vapor to be
'burned' upon startup - I found that there was a break in the diapram
allowing this circuit to be open all of the time - voila, a vaccum leak -
just like I suspected.  I happened to have an extra that doesn't have a
torn diaprham, so I replaced it.  Now, I have test driven the car for a
mile, so I haven't driven it long enough to see what the MPG is like, but
I don't think it has set a CEL yet - we will see and I will keep you
updated.  Thanks again for all the input.


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