A few questions to help in the diagnosis:
Was it working OK before you cleaned the carb the first time?
Do you have normal power and acceleration up to 40 MPH?
Have you done any work on the governor?
Is there any noticeable fuel leakage between the carburetor casting parts?
Is the butterfly valve plate tight on the throttle shaft? (If it doesn't move
around, it's probably OK. If it's loose, don't try tightening it until you've
read the instructions in my carb overhaul article).
You might remove the air emulsion tube from the top of the carb and
double-check it to make sure that all of the openings and passages are clear.
It's the most common thing to clog up, due to the small orifice sizes, one of
which is about the diameter of a human hair.
Ignition is also a possible problem area, although if you just cleaned the carb
before the problem developed, I'd lean in the fuel direction instead of
ignition. Problems with points, condenser, noise filter capacitor, cap, rotor,
coil, centrifugal advance, loose breaker plate, etc. etc. are all candidates.
Plugs and ignition wires are less likely, since it isn't likely that more than
one would go bad at a given time. Re-check my distributor overhaul article.
Articles are at: http://todacosa.com/html/m37-pw-service.htm
Allow a few minutes for each article to download, due to number of images.
Good luck,
Alan
Shaun Hayes-Holgate wrote:
> Hey folks I wonder if you can help me with a problem that has recently
> occured with my M-43.On a recent highway journey I was'nt able to get the
> truck going faster than 40mph and it kept hesitating slightly.I had just
> cleaned the carb
> the day before.Anyways it has gotten worse and I can't hit any of the high
> speeds without it backfiring and hesitating.So once again I took out the
> carb and gave it a really thorough cleaning,put a new fuel filter and hose
> in and
> poured some carb cleaner down its throat for good measure and whattaya know
> same thing.So it must be the ignition right? Well I'm getting a good spark
> from the plugs,90psi compression on all cylinders,replaced the distributor
> cap to make sure and timed it manually and with a timing gun.Still shakes
> and bangs
> when I rev it too high.Its been running good all summer and then this just
> pops up out of nowhere.Any feedback is greatly appreciated. Thanx.
>
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