From: Antonio Regazzoni (Home) (antonio.regazzoni@bluewin.ch)
Date: Tue Sep 02 2003 - 02:20:27 PDT
Hi List,
I finally solved my M151A2 starting problem ! The culprit was a faulty ignition
coil. I found a spare one from another engine and I could check mine and
this one with an ohm meter. Mine had an interrupted high voltage winding !
Eventually, if the batteries were well charged, the higher voltage could
overcome the interruption and produce weak sparks, good enough to start
the engine. As soon as the batteries voltage dropped just under 24 V, it was
not enough to start it.
The pulsating gas story has become clear to me too. It happens only if the
carb bowl is empty. By cranking the engine in this situation, the float is
in a down position and the fuel starts filling up the bowl. The pressure
increase inside the bowl pushes the fuel up through the large jet in the
throat. This happens until the float closes the fuel intake valve.
Now my M151A2 starts even without pushing on the accelerator with just
a short crank time, less than a second !
Now I'm ready to start using the AN/GRC-106 and AN/VRC-46 I installed on
the MUTT to contact other hams from Switzerland.
Thanks to the list for the useful help you gave to me !
Antonio Regazzoni, HB9RBS
1944 Willys MB
1974 M151A2
1975 Pinzgauer
-----Original Message-----
From: Bjorn Brandstedt [mailto:super_deuce@hotmail.com]
Sent: Wednesday, August 06, 2003 2:01 PM
To: Antonio Regazzoni (Home)
Cc: mil-veh@mil-veh.org
Subject: Re: [MV] M151A2 Starting Problem - Solved (I hope)
As you know, the purpose of the float is to keep a certain amount of gas in
the bowl of the carburetor at all times. The gas in the bowl is never under
pressure. The needle valve, operated by the float must close perfectly. You
can test it while rebuilding the carb by lifting the float and blowing
through the fuel entrance.
If the gas is "pulsating" down the throat of the carb while cranking, then
you may be seeing the effect of the fuel pump pushing gas through the open
needle valve. That should not happen, the gas is sucked in by the vacuum in
the intake manifold. Check the needle valve!
Bjorn
>From: "Antonio Regazzoni (Home)" <antonio.regazzoni@bluewin.ch>
>To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
>Subject: Re: [MV] M151A2 Starting Problem - Solved (I hope)
>Date: Wed, 6 Aug 2003 11:03:07 +0200
>
>Hi Ken, list,
>
>the float has horse shoe shape and is cracked vertically on one of the
>external curves.
>The crack is very thin and it barely opens when you try to close the C
>shape extremities together with
>your fingers. The float has not been glued together because it is still
>in one piece and the pivot bracket
>is still firmly attached to it. I set the clearance at 3/32 when closed
>and 3/8 when open. I got these figures from the US Army manual. The
>nylon tip of the fuel shutoff valve is in like new condition, very clean
>and shiny. So was the old one too. I will try to replace the float from
>a spare carb of a friend of mine who owns the only other M151A2 here in
>Ticino, southern Switzerland.
>
>I will keep you informed ...
>
>Thanks ...
>
>Antonio
>
>-----Original Message-----
>From: Muttguru@aol.com [mailto:Muttguru@aol.com]
>Sent: Tuesday, August 05, 2003 6:51 PM
>To: Military Vehicles Mailing List
>Subject: Re: [MV] M151A2 Starting Problem - Solved (I hope)
>
>
>In a message dated 05/08/03 16:08:57 GMT Daylight Time,
>antonio.regazzoni@bluewin.ch writes:
>
><< I have a cracked carb float. >>
>
>
>Antonio,
>
>this could be the problem. Did the float crack and get glued back
>together?
>Did it break loose from the metal pivot bracket? If one f the float
>"arms" was
>cracked, how did you ensure that the float clearance (closed position)
>was
>correct? What clearance did you set the float clearances (open and
>shut)?
>And finally, was the nylon tip of the fuel shutoff valve in good
>condition?
>(no nicks, burrs or groove worn into it)?
>
>
>There should be some evidence of fuel spraying through the carb when
>cranking, but nothing excessive, and certainly not pulsing out like you
>describe.
>
>Ken
>
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