# Honda GX690 on propane (NG coming)



## FlyFisher (Jun 30, 2018)

I got my GX690 powered 15kw unit running on propane today. I didn't run it long, just test fired it. I will do some more with it tomorrow - on natural gas also.

After wearing the skin off a few fingers pulling the cord start on my smaller unit trying to get it to run on propane the electric start is a blessing. 

I wasn't sure how to mount the regulator. The hose between it and the manifold is quite long - I haven't sized it up yet and I am not sure if how I have the regulator set is how I want to keep it. I have some commercial wall bracket channels that I've used for various projects. I threw this mount together on a whim looking around the garage for something to mount the regulator to for testing. A few cuts, deburring, welding, and drilling/deburring 1 hole. Works fine for now.










The manifold is home made out of 3/4" plate steel. 










When I drilled out the coarse outline/corners I cut too much material out so I filled those back in a bit with weld then ground smooth. This way the seal is maintained around the intake.










Not "pretty" but totally functional. I wish I had a mill, but this wasn't too hateful all things considered. Tooling included a floor pedestal drill press, vertical band saw (horizontal at first to cut the raw blank then vert to trim the exterior shape), angle grinder, and a 1/4" NPT tap for the barb fitting. For cutting the interior between larger holes I used a jig saw - and broke about 5-6 blades. I suppose you could throw in there a stick welder but if I did a better job on the hole layout I wouldn't have had to use it.


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## FlyFisher (Jun 30, 2018)

I got the natural gas hooked up today. The only way I can get the engine to run is to hold the primer button in on the regulator. 

When I run on propane it works fine. 

With the primer button pushed in on natural gas there is enough gas behind the regulator to get the engine to run fine with no load. I haven't made it to load testing since I can't get it to run without the primer button pushed in. However - the point is if there wasn't enough gas in the line I wouldn't be able to get the engine to run as well as it does, period. 

So that brings up the question - what am I doing wrong? Do I have the wrong regulator? This one is supposed to be good up to a 40hp engine - and the GX690 is around 22-23hp.

Is it a pressure/vacuum issue that I am just not getting enough draw from the intake on the engine to pull enough gas through the regulator? I opened the load block as far as I could so there was no restriction from it. Its like the regulator is too "stiff" and I can't get just the draw from the engine running to pull enough vacuum to get the gas past the regulator... 

I am tempted to take the regulator off completely and put a ball valve at the end of the hose. However, there would be no protection on the line if the engine quit - which I believe is one of the key reasons for a demand regulator at the engine. 

Is there a way to lighten up the stiffness of the regulator? Maybe a lighter spring on the primer button?


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## iowagold (Jan 22, 2020)

do you have a manometer?
you need one


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