Brake Booster & Stumble at Startup

[Kurt McDowell <gmcd@domain.elided>]

George-
    I had a hesitation problem at low rpm's when I put a load on my
engine.
 I fixed It by replacing the booster. BTW, at Auto Zone, a boster/master
cylider combo
was 50cents cheaper than just the boster.  a torn diaphram
would also cause les than desirable power too the brakes.I'm not sure
about
the idle though, could just be cloged or mis adjusted idle jets. Does
your engine
diesel too? dieseling would be an indication of a lean condition wich
could be caused
be lack of vacume because of a torn diaphram.
    Grant

Date: Tue, 9 Mar 1999 01:10:52 -0800
From: George Humphrey <gbhx@domain.elided>
Subject: Brake Booster & Stumble at Startup

        I've decided to run this theory by the think tank that is the
ihc
digest, to see if it makes sense. I've had a hard starting problem on
the
Scout for sometime now (pretty much since I bought it). When cold it
starts, stumbles and maintains a very low idle or dies. If I can keep it

running for maybe 30 second or so,  it will eventually idle better.
After
that it runs beautifully for the rest of the day.
         My second problem is what I consider to be very marginal power
brakes. I've never owned a car with power brakes before and am not sure
how well they are supposed to work, But, I am guessing better than they
do on my Scout.
         Conclusion, I have a tear in the power booster diaphragm. My
stumble at start up is caused by the vacuum to the power brake canister.

It has to draw air from the entire canister, not just up to the
diaphragm. Until the shell  holds the entire vacuum  my stumble
persists.
Eventually I'm left with a smooth idling engine with poor power brakes.
          Does this make sense? I've tested the check valve and it is
okay. I pumped and pumped and pumped on the vacuum canister but could
not
get a reading on the vacuum gauge. However, after driving for awhile,
when I pull off the check valve there is some vacuum. Do Scouts have
poor
power brakes and my stumble is caused by something else? I know I should

only attack one problem at a time but it is too late to work on my Scout

tonight and my brain is working overtime. Thanks in advance for any
responses.

George H
72 Scout II
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