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Howard-B 07-27-2012 02:03 PM

Generator with Tri-fuel problem
I have a ETQ TG72B12 7.25kW generator that uses a 420cc 14hp engine.
I added a Aardvark Tri-Fuel kit and it still runs good on gasoline and even better on propane but I just can't get it to run on natrual gas.
The initial suggestion was that the NG gas line was too small or the meter/regulator wouldn't supply enough gas so I had the gas company change the meter (they said that regulator is fine) and I tapped the main pipe in the house at 8 feet from the meter.
The pipe is 1.25" ID and the tap is a 1/2" valve feeding a 8' hose (1/2"ID) direct to the genset. Measuring the pressure at the generator it is 5.5"wc static pressure and 5.0"wc with the generator running.
When I say running... it's VERY difficult to get it started, it runs really rough, and with any load it will conk out.
Aardvark now says that it is probably the ignition and that "With the China generators, it comes down to the timing of the engine spark. Sometimes NG
is out side its range."
If anyone have any experence with this or can make any suggestions it would be greatly appreciated.


Auger01 07-27-2012 04:57 PM

Propane has about 2.5 time the btu of natural gas. If you are not adjusting the mixture when you switch between the two then the engine would run very lean with natural gas.

That line about ignition sounds like BS to me. If it sparks fine with gas and propane then using NG wont change that.

BTW my trifuel gen specifies between 7-11" of WC. If all else fails, you might try adjusting your NG supply up to 7".

Howard-B 07-27-2012 05:41 PM

Thanks for the reply.
I do re-adjust the regulator for NG and get it to run the best that it can but it is still really poor. Takes a lot of priming to get it started and like I said really runs bad. Our NG service is fixed at 5"wc and the gas company won't change it. They say that they would have to install a new additional service for a different pressure, so that's out of the question....

I also think that the timing answer is wrong but I don't have a lot of experience with small engines so it is worth a shot to ask. Thinking about trying a different spark plus if I can find one hotter. Again, a new area for me.

If I can't get this to work I will have to resign myself to storing Propane and gasoline, not something I want to do.

Auger01 07-27-2012 05:53 PM

Your NG company probably wouldnt appreciate it, but the regulator on your meter IS adjustable and if you have a manometer, you could adjust it up a bit. If you keep it less than 11" or so, it souldn't hunt any of your gas appliances. Also, 1/2" line is marginal for a 14 horse engine, but if you are only dropping .5" W.C. then it is probably ok.

What is the btu rating of the regualtor btw?

Protocol. 07-27-2012 07:27 PM

How many cf of NG is it rated for? Pressure shouldn't be dropping too much with a properly sized supply line. Remember, pressure and flow are two different thing.

7 inch wc is pretty standard as well. I wonder what the real reason for only having 5 is. I would also think if the spark plug is running the unit, it's running the unit.

I honestly think this is a too little fuel situation.

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