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jtaylor9

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Reply with quote  #1 
I have a Briggs & Stratton Power Boss with a Honda GX390 engine.  It was running on gasoline the first time I used it, and it ran fine.  Last year I bought a Tri-Fuel type C kit and the electronic tach, and converted the generator to NG, and the conversion went uneventfully.  The generator started right up, and I set the fuel block according to your instructions.  I didn't need it again until this weekend.  Now the fluorescent lights flicker.  The generator says it produces 68 amps at 3600 rpm.  The tach says it's running at 3720.  Does this cause the frequency to be higher than 60hz, and cause the lights to flicker?  I cleaned the gas out of the carb since I'm not going to use it on gas ever, so I can't try it on gasonline to see if the problem goes away.  The Honda doesn't have an idle setting, it just runs wide open, so the speed control is very simple. It's obvious how to change it, but I don't want to change something I'm not familiar with.  I can't find the speed specifications on either the Honda site or the B&G site. They say "the unit should be serviced."  What should the operating speed be?
Thanks!
Master Tech

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Reply with quote  #2 

You mention that the tachometer read 3720.  I would suppose that you have no “real” load on the generator.  I would not bother with trying the gasoline because it is not unusual for a non-loaded generator to tach out at just over 3700 rpm.  I would assume if you put a decent sized load on the generator the governor should keep the speed more in the 3600 range and the flickering should go away.  The fact that the additional hertz are causing the flickering should not cause any harm but it sure is annoying, well, not as annoying as “lights out!”  Try the load test and let me know how the lights react.  Also, are these lights the long tube shop type lights or the newer spiral type?  That may be a whole new topic for generators if it’s the latter.

 


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jtaylor9

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Reply with quote  #3 
The lights were 48" T12 tubes, the classic shoplights.  The generator was under a pretty good load, 2 freezers, a refrigerator and a wine chiller that were running full bore, plus the lights in the house.  The tach read 3680 or 3690 I think.  I guess the next time the power goes out I should check the speed and adjust it.  I have a load control box that switches the load between the generator and main power, so I can't just hook the generator up to the house to try it.  Maybe I can get my wife to stand on a chair and hold the test button in for 20 minutes while I fiddle with the genny!  Right!  ;->>

Changing the max fuel block should not increase the speed, right?  It just limits gas flow at max usage, if I understand it correctly.
Thanks for the quick response.
jt
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Reply with quote  #4 
Yes, the load block is just that; a calibrator that block additional fuel above the load amount needed by the particular engine size it is installed on.  Never should it be used to manipulate engine speed.
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mtcman42

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Reply with quote  #5 

Thanks for this answer.  I suspected that the load block was not used to control engine speed, just to make it run more evenly.  The engine speed is the job of the governor.  I first got the engine to run evenly and then backed the load block screw out about 1/8th of a turn more to make it just a tad richer ( a 1/4 turn was too much) in anticipation of needing more fuel under load.  I am pretty sure that there is an adjustment screw somewhere that will tweak the engine speed a little either way.  I'll look for it tomorrow and report back.  In my particular case, the engine speed varies between 3600/3660 with no load and 3540 with a moderate load.  I have yet to really load it down and check the RPM's, or the voltage.  If the RPM's stay lower under a good load, then I'll re-adjust governor and the load block to bring it back up.  Thanks again.

bvinman

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Reply with quote  #6 
I seem to have the opposite problem.  I installed a tri-fuel kit on my 7000K watt generator using the CIC mod to my carburetor and the generator runs fine at idle and with a small load of about 2000 watts.  But if I put a larger load on it (say around 4000 to 5000 watts) my RPM's go from 3660 to around 3900; sometimes even over 4000.  Then when I remove some of the load it goes back down to a more normal 3660 to 3720.  Anyone know why this is happening?
lastfsdfsd23

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Reply with quote  #7 
i have this same problem. how it solve?
Furd

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Reply with quote  #8 
Does it also do this when using gasoline?  If yes, then it is an engine governor problem.  If no it is most likely a propane/air mixture problem.  The latter could be caused by a vacuum leak, a maladjusted load block or possibly a seriously out of calibration zero pressure governor.
bvinman

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Reply with quote  #9 
Unfortunately it really hasn't been resolved. At first I thought maybe if I open the load block screw a little more that would help but it didn't. I have to perform the same test using gasoline and see if it does the same thing. I'll report my findings once done.
bvinman

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Reply with quote  #10 
I was finally able to test my generator on gasoline to see if the RPM's would surge to 3900+ under max load and the results were that it did NOT surge using gasoline.  The governor worked correctly in that it maintained a 3600 to 3660 RPM under MAX load (roughly 6500W - 7000W).  I then hooked up the genset to NG and put a 4500W load on it and the RPM's were good at roughly 3660 to 3690 but once I put on another 2500W (totaling roughly 7000W) the RPM's went up to about 3800 to 3900 RPM's.  It would sometimes come back down to around 3750 but for the most part, it stayed at 3800 or higher.  Once the load was reduced to around 4500W the RPM's went back to a normal 3650 to 3690 RPM's.

My question is:  Is this because the generator will only produce a max of about 5000W under NG or there another issue?  I did back out the load block another half turn while the generator was under max load using NG but it did not seem to make much of a difference.  It is safe to assume that I should not put more than 5000W on the generator using NG being the BTU differences with gasoline?
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