From: bjgaed@bb1t.monsanto.com
Subject: Re: Beetle carb help
Organization: Monsanto Company, St. Louis, MO
Distribution: usa
Date: Tue, 5 Jan 1993 14:50:35 GMT

In article <1993Jan4.210849.2894@slc.com>, jimk@slc.com (Jim Kenney) writes:
> I need some fuel system help (I think).
> 
> I have a (mostly) 1976 Beetle (non-super) that is supposed to have
> fuel injection.  During the 100k rebuild (about 10k ago) done by
> a real mechanic for the previous owner the ENTIRE fuel injection system
> was pulled off and replaced with a 34 PICT-3 carb of unknown ancestry.
> Unfortunately the exhaust system's pre-heaters for the fuel was NOT
> changed so I have only a jerry rigged system to put a little warm air
> into the air cleaner.
> 
> (Pause to let the laughter die down)
> I know, but the car was cheap.
> 
> 
> I have a few  questions:
> 
> 1) If I stop very quickly the engine's RPMs will drop and the engine may
>    die.  This is more of a problem going down a hill than up a hill.
>    (yes I do push in the clutch pedal).  Do I have a float valve problem? 
>    Do I need a carb rebuild?

Could be a bad float valve or float which would let raw gas leak down 
the carb throat, but that should cause fouled plugs (black deposits).


Also, was the automatic choke hooked up on the carb?  There should be 
a wire from the choke to the electromegnetic cutoff jet to the 
ignition switch (hot) wire on the coil primary terminal.  If the choke 
(oops, just made a Freudian typo; typed "joke" instead of "choke") 
isn't connected or isn't adjusted properly that could be the poor 
mileage problem, but again you should see carbon fouling on your 
plugs.  Your symptoms are the same as my 40 hp before it warms up as I 
don't use a choke at all.
 
> 2) I have to set the idle up higher than I like so the engine won't die
>    die when I stop.  The idle does not want to stay at a single value
>    but will change without notice by several hundred RPM.  Is this because
>    the fuel preheat is not hooked up?  The fuel mix SEEMS OK (no carbon
>    fouling on the plugs) but I am getting only 17 to 18 miles/gallon
>    on the highway.  The State of Oregon emissions folks do frown a bit
>    over my hydrocarbon emission levels.

I had the same problem with that carb on a 72 bus.  There was a little 
gizmo called a "dashpot" that acted like a shock absorber to ease the 
throttle down slowly to idle, thus allowing the idle jets to take over 
from the mains in the carb.  Seems the fuel level at the idle jets 
would drop back under open throttle conditions and it would take a 
while to fill the drillings when transitioning to idle speed.  Also 
may need a vacuum operated throttle positioning lever to feed a little 
extra fuel when slowing down quickly.  Both of these used to be 
handled by the fuel injection computer, so yours may not have the 
mechanical systems needed for these functions.
> 
> 3) Should I put a carb-compatable exhaust on this thing (some of the exhaust
>    system has some spots rusted through) or just wait and sell this beast
>    to some dune buggy builder next year?

By all means.  The lack of a manifold preheater system would cause the 
symptoms you describe, like having a plugged heat riser pipe.  
Surprised you passed inspections with rust holes in the exhaust.


> This is my cheap-to-buy 50 mile round trip commuter car and I would like to
> keep it going for another year.  I have the Hayes book and the "How to keep
> Your Volkwagen Alive" book by Muire (sp?) and they are no help here.
> (These are very good other problems and I highly endorse them.)
> 
> 
> Any advise gratefully accepted (but I already know I am crazy so I already
> know I need my head examined).

Sounds like a VW [A] owner to me. 8{)
 
> Thanks
> 
> 
> Jim Kenney     jimk@slc.com
-- 
By all means keep that little beauty on the road.  There will never be 
any more of them in the USA, so we need to conserve all we've got.


--Electric Monk            (Bruce Gaede); 
                            e-mail: bjgaed@ccmail.monsanto.com

"...and then time started seriously to pass."
--Douglas Adams, _Dirk Gently's Holistic Detective Agency_