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the good news is the generator lives. I replaced the fuel lines and the spark plug. It is not a bad oil pressure switch, it ran fine with and without it disconnected. Bad news is it is making too much voltage, ~170V @ 120 outlets and ~340V at the 220V outlets. I did some checking on generators and over voltage and I think it's running too fast. I did notice before checking the voltage that it seemed to be running 'better'. I've looked up how to adjust the throttle. This is a DeVilbiss GT5000 portable, I don't think it has a voltage regulator on it. Question is, is adjusting the throttle and then checking voltage reliable? I don't have a tachometer and don't have an RPM to voltage table even if I did.
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11-27-2017, 01:01 PM
(This post was last modified: 11-27-2017, 01:07 PM by TDKPE.)
It needs to run at 3600 rpm, assuming it's a 2-pole generator, which is a near certainty. Otherwise your motors will over- or under-speed, and some power supplies will get confused. It's unlikely the voltage regulator can compensate for a large over- or under-speed condition.
With no tach, you can plug a small induction motor (with no load attached) into utility power, then into the generator (on a long cord, so you can hear the motor) and compare the pitch. Also, a fluorescent light aimed at the strobe bars on a turntable (if you have one that has a strobe), running on utility power and then on generator power (the light, not the TT) might work. But your hearing is very sensitive to pitch, so an induction motor under zero load runs just a thin shade under synchronous speed (1200, 1800, 3600 rpm), and you can hear small changes in motor speed, like an unloaded TS at 1790 rpm or so, loaded down to full load at 1725 or 1740 rpm, which is only a little more than 4% less than synchronous.
But a multimeter with frequency function is the best way to go here. Or a mechanical tach. Even HF.
Tom
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Run down to harbor freight and get a kill-o-watt meter. It will give you voltage and hz. If it running fast, hz will be off. Otherwise, check voltage with a load attached. Unloaded may not be accurate.
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I used this as an excuse to upgrade my multi-meter to one that tests frequency, I've been wanting to upgrade it anyway.
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(11-27-2017, 04:39 PM)crokett™ Wrote: I used this as an excuse to upgrade my multi-meter to one that tests frequency, I've been wanting to upgrade it anyway.
My bet is the voltage regulator. Engine speed is going to have a bigger effect on frequency than voltage.
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(11-30-2017, 07:33 AM)Snipe Hunter Wrote: What got it running?
at this point I'm assuming clogged fuel line. Replacing the carb didn't work. replaced the fuel lines, that worked. oil switch connected or not didn't seem to matter.
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(11-30-2017, 10:40 AM)crokett™ Wrote: at this point I'm assuming clogged fuel line. Replacing the carb didn't work. replaced the fuel lines, that worked. oil switch connected or not didn't seem to matter.
I've had issues with outboards with older fuel lines getting what looks like "gel" in the lines. Pretty sure it has something to do with ethanol in fuel. Some passes through and into the carbs and I lose a carb.
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My honda generator manual says not to use fuel with ethanol for this very reason. Around here Liberty is the only gas station that I have found that has ethanol free gas.
My nephew is a mechanic. He told me that they replace all of the small engine fuel lines yearly because of ethanol damage :preventive maintenance.
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12-01-2017, 10:20 AM
(This post was last modified: 12-01-2017, 10:36 AM by crokett™.)
well this generator is 15 years old, so I'm guessing 15 year old fuel lines were the issue, not ethanol fuel. Personally, I've always run ethanol treatment +stabilizer in the gas for my small engines and haven't had problems. For sure I don't replace fuel lines yearly.
In any case, I did more testing today. subjective test with an incandescent bulb it seemed to be brighter plugged into the generator than the house.
a new meter with frequency measurement - this one:
https://www.amazon.com/gp/product/B071JL...UTF8&psc=1
I verified the meter and my own understanding by measuring the expected 60Hz at an outlet in my shop but 1.2 Khz at the generator, on the 120V side. I'm not sure what's going on there. 1.2, 12, etc is a multiple of 6. that might or might not be significant.
I messed around with adjusting the throttle, this video is to the same engine I have
https://www.youtube.com/watch?v=GWFMbOpoKvI
backing the nut on the throttle spring all the way out didn't seem to change the sound on the engine any, it was still throttled all the way to the stop.
manually throttling down while watching the frequency I throttled it to the point of nearly stalling, it didn't seem to change the meter.
I did not retest voltage with a load yet.
On the plus side, I don't need starting fluid any more to start it cold.
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