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Wisconsin Engine VH4D Running Rich

Jason Blixrud

Registered
New to this site. Have a Wisconsin engine in a Bobcat M700. Runs rich after about 1 he to1 1/2 hours of running. Carb cleaned and rebuilt at dealership...I am an everything else guy not a carb guy. Timed, all new cap rotor plugs condenser, etc. Replaced fuel cap. Covered fuel lines with 2 types of heat insulation in case it was a vapor locking issue. Still same result. It has an electric fuel pump. Could it need a regulator to make sure fuel pressure stays at about 3 psi. Or should I do a compression check first..help please thank you
 

Craig A

Moderator
Staff member
Age
68
Last Subscription Date
12/20/2015
Re: Wisconsin engine Vh4d running Rich

Welcome to STAK Jason...…. :clap:

I moved your thread to this forum so you'll get some suggestions.
 

I like oldstuff

Registered
Last Subscription Date
11/09/2015
Re: Wisconsin engine Vh4d running Rich

Is it making black smoke from the over rich flooding condition?
When it is running rich next time, shut it off and pull a spark plug. Is the center insulator black or very dark brown?
 

DCamp

Subscriber
Last Subscription Date
03/05/2019
Re: Wisconsin engine Vh4d running Rich

If you are running the engine to slow it could overheat. Mine sometimes will do that in hot weather so I add a little diesel to give it extra lube.
 

Unicam

Registered
I have yuge issues with vapor lock and carb boiling. ( two different symptoms)

mine runs like a dream all winter plowing snow, dare i say never an issue. But the summer is one issue after another.

wisco has published a few suggestions for usage in high temp areas but with the poor gas these days I've seen data showing vaporization at as low as 130-140*f.

wisco has a gas recirculation kit in old literature that helped to prevent vapor lock which helped eliminate stalling.

they also have a suggestion to carb boiling that creates a rich mixture. they recommend cutting partially threw the "heat bridge" between the exhaust and intake manifolds.

amongst the things i've tried, running premium fuel and swapping my manifold has helped the most. I saw a guy on the bobcat facebook page who's machine had the exhaust on the opposite side of the carb. in the factory configuration they had the exhaust manifold OVER the carburetor bowl area. I swapped mine and now the carb is more open to air movement but i have yet to plumb the intake as it wouldn't fit without contacting the exhaust manifold. i'd go as far as to recommend trying this if heat continues to be a problem because i think this should really help.
 

I like oldstuff

Registered
Last Subscription Date
11/09/2015
90% of carb problems are ignition problems. Try a new condense first if it has points. Then the coil.
 

Unicam

Registered
thats an example picture of what it looks like with the manifold swapped 180*. it's not my engine, it's my understanding this was a mid-rebuild picture. i'm sure he has shrounds.

interesting observation about ignition being the real problems of carb problems... i have no idea how many carbs i've had to clean in my life, needles sticking etc compared to how many ignition parts i've replaced but i'd have to venture a guess that for me it's not even close. carbonators are far more problematic but i was born in 73 and electronic ignitions were basically all i ever dealt with.
 
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