Allen & Frank,
Frank's correct. The sock in the gas tank could be coated with crud and
blocking fuel flow. If that's the case, simply throw the sock away and
replace the inline fuel filter you should have up front to protect the carb.
Actually, an inline fuel filter should be ahead of the fuel pump to protect
it also.
Milton Schick
1964 442 Cutlass
[EMAIL PROTECTED]
----- Original Message -----
From: "Frank Siano" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, April 10, 2006 8:17 AM
Subject: RE:TH400 Slip Up
Allen
I would like to add one more possibility to this
problem. The fuel line sock filter in the fuel tank
is collapsing under WOT causing the fuel starvation
by plugging the fuel line inlet.
I had this problem in my 68 442. The car would
launch great and run hard up through the gears.
Then, just prior to shifting into fourth or right
after shifting into fourth (hard to remember 30 year
old details), it would fall flat on its face. Though
the car is a four speed the symptoms were exactly the
way Milton described. I checked the carb for issues,
replaced filter in the carb and the in-line filter,
and
checked the fuel pump. The pump passed flow checks
but
replaced it anyway. Still fell flat at about 90 mph
on WOT run. When I let off the throttle the fuel
system would catch up and the car would accelerate
again. If I part throttled up to that speed, no
problems were noted. Father of a friend was helping
me trouble shoot the problem, he knew Rochesters
inside
out, asked if I ever changed the filter in the tank?
I said what filter? Did not know there was one.
Dropped tank, pulled the sending unit, and put on a
new sock filter. Flushed out the tank. Reinstalled
everything. Problem fixed.
I do not know if GM stills sells this part, for some
reason I think I read somewhere that they don't but
I think someone is reproducing it. If everything else
fails I would give this a try.
Frank Siano
on digest mode
[EMAIL PROTECTED]
Date: Sat, 8 Apr 2006 14:18:58 -0700
From: "Infinite Space Systems, Inc."
<[EMAIL PROTECTED]>
Subject: Re: RE:TH400 Slip Up
Okay, lets do this again.
> Sorry about the racing freely description, my bad.
I have enough
> experience and knowledge in this area to be
misleading, but I am learning
> from everyones replies. Thanks. When the fellow
took my car car out,
> what I thought was the engine roaring was that the
engine did rev higher
> once it drop down a gear, but that it could not
rev high enough to
> increase the cars speed, but as you let up on the
gas the tranny would
> shift up, and now the engine could pull the car
better. I don't want to
> attempt to describe the sound because I may
mislead, it just didn't sound
> like it was bogging. The choke does seem to work
well. Fully closed when
> cold, secondaries appear to open properly when
engine is warmed up
Allow me to describe something and tell me hoiw
close I've gotten to the
symptoms.
You accelerate at WOT. The engine speed and car
speed increases to a certain
point, and then it seems as if everything stops. Car
speed stops increasing.
Engine speed stops increasing. It's as if everything
has paused at that
engine speed, and the transmission doesn't want to
upshift. The engine may
or may not have a miss. You let off the gas, and the
transmission instantly
upshifts. You put your foot back into the throttle,
and the engine increases
speed again.
How close is that to what you're experiencing?
If I *have* described it correctly, then you are
running out of fuel. The
lower the gear for acceleration, the more demand for
gas. Why? Because the
wind up to maximum RPM is quicker and needs a large
volume of fuel very,
very fast. The fuel pump is not delivering enough
gas volume, probably due
to some type of porosity in the fuel pump diaphragm
which *will* greatly
decrease delivered volume. As the engine tries to
wind up in first or second
gear, the engine demand drains the carb fuel bowl(s)
too quick and the fuel
pump can't keep the fuel bowl(s) full enough to
supply gas to the jets and
venturi clusters. Therefore, the carb and the engine
runs out of gas. You
take your foot off the throttle for a second, heavy
demand is removed off of
the transmission, so it automatically upshifts, the
throttle plates on the
carb momentarily close boosting the engine to high
vacuum which facilitates
drawing large amounts of gas back into the engine as
soon as the fuel volume
catches up, the fuel pump has a split second to
catch up and get some fuel
into the fuel bowl(s), the engine drops to a lower
RPM due to the upshift,
so the fuel pump can catch up to the lowered RPM and
fuel flow demand, the
high engine vacuum causes the carb to flow gas
again, the engine catches gas
and then makes power, and you surge ahead.
***If*** everything matches what I've just said, and
the reasons for it, you
have a bad fuel pump. The transmission is okay.
I suspect this situation due to your statement about
no fuel being available
for startup and having to pump and crank the engine
a bunch to start it.
Milton Schick
1964 442 Cutlass
[EMAIL PROTECTED]
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