Converting Generac Generator from Gasoline to Natural Gas

 

I purchased the Fuel induction Kit from USCarburetion and installed it
on my 33HP Generac engine. The engine will run fine (No sputter and at
3600RPM) using NG. However for it to run, I must engage the choke half
way and adjusting the load block for a lean burn. My concern is that
the engine appears to be running hotter as I noticed the intake
manifold to be quite warm to the touch while using NG as opposed to
gasoline. Is this normal, or does the timing or any else need to be
adjusted?

 



Yes, the warm manifold is normal.  Liquid gasoline evaporating carries
away heat, thus the cooler manifold.  NG, since it is a gas has no
such refrigeration effects.

However, you still have a problem, one that potentially will cause
engine damage.  The mixture is obviously too lean.  Generally choking
isn't required to start or run an NG-fueled engine.  It sounds like
either US Carb supplied you the wrong kit or more likely, there is
something wrong with it or the setup.  Did you check all the
pressures, both statically and with the engine running?  I'm betting
that there is inadequate pressure to the engine when it is running.
Check the zero pressure regulator to make sure that it starts opening
during cranking without the choke.

To gain optimum efficiency and power on NG, the timing should be
advanced a bit and optionally, the compression raised.  However, it
will run just fine with the gasoline setup, albeit with a little less
power.  Unless you're going to be running it a lot, probably not worth
the effort to make any mods.
---
John De Armond
See my website for my current email address
http://www.neon-john.com
Cleveland, Occupied TN
Don't let your schooling interfere with your education-Mark Twain

 



Did they maybe send a kit for propane instead of NG?  Most gas appliances
need minor changes to switch from one gas to the other (orifice sizes).

daestrom

 


daestrom wrote:

This is actually a tri-fuel system,( Gasoline , NG or Propane). You
mentioned that I may damage the engine by it being run too lean on NG.
I believe that running NG lean is cooler than runing rich...unlike
gasoline. As I mentioned it runs fine with adjusting the choke to about
half way. If I vary the choke either more or less the performance
decreases or shuts down. My only indication as to why the engine was
running hotter was by feeling the temperature of the intake manifold.
With that question answered, is it possible that applying some choke is
required to get the proper fuel/air mixture on this particular engine.
I'm 99.9% sure the installation/setup is correct.