In a message dated 02/12/01 14:57:03 GMT Standard Time, b52d@piace.com writes:
<< The possibilities that come to mind are leaks in the fittings to the new
valve and possibly a timing issue based on the timing being set when the old
valve was on and was broken. >>
Hello Dave....
There are a few issues here. The first one concerns the operation of the
fording valve. When the handle is pulled "out"...this valve closes off the
ventilation route into the manifold...which is the normal route for excess
pressure in the system. This is what the TM says:-
"When the control is pulled out as directed, the engine, brake, hydraulic and
fuel venting systems are connected through the fording valve to the extension
intake tube so that they can be provided with an outlet to the atmosphere
above the water line".
It is highly unlikely that even a stuck valve would cause the problems you
are encountering. Much more likely is that there is leak in the system and
this is allowing air to find its way into the manifold, causing a weakened
mixture. My best guess (from 3,000 miles away) is that there is a poor seal
between the fording valve and the manifold.
When we bought our first M151A1, the previous owner had, at some time, tried
to remove the vent valve from the manifold and in doing so, he had produced a
hairline crack in the brass, just where the threads met the manifold. He must
not have noticed this, and to compensate for the weakened mixture, he had
adjusted the carb mixture screw to "ultra-rich". We eventually discovered the
problem when the vehicle wouldn't start one dark night. There was a backfire
and I saw a slight "flash" where the valve met the manifold. When we sealed
the crack temporarily with Araldite, the vehicle ran terrible because the
mixture was now too rich for correct operation.
If you are certain that the connections are all airtight now, then it is a
possibility that the "old" fording valve was allowing air to enter and you
now have the same circumstances that we encountered, ie.....mixture now too
rich.
If you did not disturb the carb, nor the timing, when you installed the new
valve, then there is no real reason to suspect these.....in other words,
don't twiddle with these and just make matters worse.
Let us know what you find.
Kind regards.............
Ken
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