Re: filthy rich

[Greg Merritt <gregm@umich.edu>]

At 3:55 PM -0600 10/24/97, Melissa & Jim wrote:
>to the right point on each end and make sure the pressure sensor
>itself does not have a major leak in it (put a clean hose on it and
>suck with your mouth.)  Do not worry about any other hoses or small


	Problem #1 identified:  Manifold Pressure Sensor is dead (as in
"doorknob").  Can't hold a vacuum to save its life.  (Tested with mouth
directly on sensor--yum.)


	Problem #2:  it was an 051B sensor; wrong for 1971.


	Problem #3:  two other "apparently" good 051B sensors did not solve
the problem.  (Some of my spares don't seem to have part numbers for
identification...!)


>3)  Check your fuel presure to make sure that nothing has gone wrong
>with the return side of the fuel loop.  A kinked or flattened line
>here could drive the fuel pressure way up and make the mixture too
>rich.


	Problem #4:  something's screwy with the fuel pressure.  I first
tested it with the engine off by running the pump by just grounding the
test lead in the engine compartment.  The needle hit about 28-29 or so, but
constantly jittered +/- several psi.  Also, after a couple of seconds of
running, a hissing/gurgling sound comes from (apparently) the pressure
regulator.  When I ran the engine, the pressure was all over the map--the
needle bounced around like a hummingbird's wings, maybe +/- 7psi or +/- 10
psi.  I couldn't even pretend to be able to adjust if I wanted to, it's
that crazy.


>4) (Okay, I lied.)  Make sure that it is not the cold start jet by
>removing the electrical connection from the jet..  On late 71-72
[snip]
>Have you done any starter work recently?


	Unplulgging the cold start jet doesn't have any effect; also, no
starter work recently (over one year).  I'm still not ruling out a
mechanically leaking injector or cold start valve (though I couldn't wet a
probe in the intake air distributor with the pump running & engine off).


>If none of this pans out I would suggest you look around for another
>"D" brain to try.  That's a long shot, however.


	I may try this next, as there's a lot less mess involved than with
pulling the injectors.


	Would a leaky/sticking injector cause the fuel pressure gauge to
flutter all over the map?  The pump *sounds* like it's working hard &
steadily, but that's no accurate measure.  I suppose the things to do next
include pulling the injectors & watching how they're squirting/leaking,
confirming that the cold start jet isn't leaking, and then look to the
pump/filter/pressure regulator.  Also, check the voltage regulator again
(been a while).


	Any more thoughts, anybody?


-Greg
'69 & '71 Squarebacks
'63 Beetle