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  • 120 volts...but low wattage

    I have a six year old genny. 4000w 5500 surge. The battery is completely dead and has been removed. The genny has very low hours. I fired it up and found the engine is running a little funny...maybe bad gas, but other than that it sounds good. Its not bad sounding after she gets going. Problem is the volts are fine, but the wattage is greatly decreased. I can barely fire up to 2000w. So the output of this genny is about half of what it should be. What gives? Will a service and new battery fix the problem? or is it an electrical issue.

  • #2
    Re: 120 volts...but low wattage

    You have to make sure the engine will increase in rpm's as the demand for more wattage is made. Just because the engine "sounds" good doesn't mean it will rev up when needed. Run an extension cord far enough away that when someone plugs in a couple things like a hair dryer and circular saw, you can hear the engine rev up to meet the demand. Could be that simple, especially if the carb and linkage are gummed up. Good luck and let us know.

    Comment


    • #3
      Re: 120 volts...but low wattage

      actually a generator runs at one RPM, 3600 for a two pole and 1800 Rpm for a 4 pole unit,
      yes the Governor needs to be operation correctly, and the throttle does move but the RPM should not fluctuate more than a few %, that is how it keep the 60 cycles correctly,

      so one should hear it lug down or go in to what is called a high Idle (no load condition),
      but the speed should basically remain constant, (unless it has a special no load detector like an engine powered welder may have, that varies the throttle setting to a low idle).

      poor fuel may be the cause, as it many times does not have the power to allow the proper power out of the engine, I would drain out the fuel, (I would run the unit dry to store as well), and fill with fresh fuel, if that does not help the problem I would consider some thing like "sea foam" fuel treatment, and see if that may help it may take a while if the jets are varnished over, (especially if the current gas is very nasty).

      (gasoline, is a multitude of different things, and there are substances in fresh gas such as dissolved gasses such as propane, all the way to a heavy resin type products), when burnt they normally are burnt and expelled out the exhaust pipe, but if left to evaporate that is where the problem comes in,
      the light items evaporate off fast, (part of why gas goes bad so fast), and becomes hard to ignite easily, and as more and more of it evaporates off it gets thicker and thicker, losing BTU's in the process, but if left long enough it will leave a resin or varnish on things, and that can plug up small passages and gum up things).

      I do not know if that is your problem but I currently can not think of probable or logical electrical problem that would cause what your describing, (or what I think your describing)

      the battery should have nothing to do with generating the electricity, it should be for starting the engine, (but if not using a battery keep the battery terminals Insulated so they do not short out, as there is a alternator in the motor for battery recharging and one would not want to damage that).

      what exactly is happening when you get to about 2000 watts of load? does it just not have enough engine power to keep running, or does it keep running fine and there is no power all at once, or what exactly is the symptoms of the situation?
      Last edited by BHD; 09-26-2009, 01:04 PM.
      Push sticks/blocks Save Fingers
      ~~~~~~~~~~~~~~~~~~~
      "The true measure of a man is how he treats someone who can do him absolutely no good."
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      ~~~~~~~~~~~~~~~~~~~
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      • #4
        Re: 120 volts...but low wattage

        BHD knows the magic of good old SeaFoam. I would also feed the engine a gallon or two of Shell V Power 93 super gasoline. It has some good powerful internal engine cleaner in it. With SeaFoam + Shell V Power you are really cleaning things up nice. By the way at the proper mix ratio it works wonders for ALL gasoline fueled engines other than those that must burn oil such as two cycle ones requiring mixed fuel or that have oil injection into the fuel system. Put simple for your car, truck, farm tractor and small 4 cycle engines give this stuff a try.

        Please try that and also drain out the old oil well and fill it up with new "Small Engine" oil that is SAE 30 weight unless the engine is of overhead valve type in which case use a good non synthetic 10W-30 oil such as Valvoline "All Climate" or maybe Castrol GTX.

        Run your generator under a moderate load and with even loads plugged into all of the 120 Volt receptacles. I would aim at say 200 Watt light bulbs as your loads. Let it run a few hours. It might be that the magnesium needed for exciting the generator is weak from storage. I doubt that's the case but some good running should help it.

        My bet is either you have a messed up Voltage regulator (for generator) or that the engine speed governor is glopped up and needs cleaning. Get some spray SeaFoam and blast all moving parts of the carb with it, let soak a few minutes and wipe dry with paper towels which should be laid on your driveway to air dry or burned. Don't put them into a trash can, please.

        Note: Spraying the moving (external only) parts of the carb which need to move and any linkage with WD-40 should help loosen them up. Do not get any inside of the engine.

        Is your air cleaner dirty or a mess? If yes it needs service.

        BHD once again points out that you need pretty constant engine speed. Under no load about 3-5% fast is normal and under full Continuous load it should be pretty close to exact speed. Under a slight overload such a the peak or max rating under speed by as much as 5% is OK.

        Example: No load = 3775 RPM
        At rated continuous power = 3600 RPM
        At max or peak power = 3425 RPM and that's with the engine really grunting hard.

        You want to have better than the above. Aim at more like this.

        No load = 3750 RPM max
        Rated load = 3600 RPM
        Lugging hard = no less than 3500 RPM and that's only for no more than 10 seconds out of a 15 minute run. Think of a hard starting big motor as the load.

        What brand is the engine? Model of engine? Brand and model of the generator?

        When loaded, does the engine speed drop much? Does it grunt and snort or just pretty much slow down and stall out under a good load?

        Comment


        • #5
          Re: 120 volts...but low wattage

          Wow...you guys are serious about generators. I am a member of many different forums and few have been as helpful as this forum. I am very impressed.

          The engine does lug down, but it is far from stalling. The volts stay constant, its just I should be able to have more than 1978watts thats about half of the continuous watts this thing is supposed to put out. I will try the engine (sea foam) service and see if that helps. I will get back to you guys and let you know. I am taking it that no one things it is an electrical problem with the genny then...thats good.

          Comment


          • #6
            Re: 120 volts...but low wattage

            If this is a 220V capable generator then it is functioning correctly.
            It will produce 2000W on each 'side' @ 120V. When you add the two halves of the generator together you get 220V @ 4000W

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            • #7
              Re: 120 volts...but low wattage

              the voltage regulator is working if you have the voltage,

              the voltage regulator takes a measurement of the out coming voltage either in the 110 or 220 voltage and then supply's the rotating part more or less volts to make the voltage correct, the voltage in the rotating core of the generator is DC, (most all are a small solid state box any more).

              and the amps capacity is basilcy a determination of the wiring size used in the generator,
              and the amount of power that can be applyed to the rotating shaft, by the motor,

              If your motor is over sized you could fry the generator and if under sized you will not get full potental out of the generator, (or if it is not producing full power),
              Push sticks/blocks Save Fingers
              ~~~~~~~~~~~~~~~~~~~
              "The true measure of a man is how he treats someone who can do him absolutely no good."
              attributed to Samuel Johnson
              ~~~~~~~~~~~~~~~~~~~
              PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

              Comment


              • #8
                Re: 120 volts...but low wattage

                Hey guys, thanks for the "Small Engine and Generator 101" course. Very informative.

                I will have to look up this Sea Foam stuff.

                My two cents. For gasoline intended for small engines and gas cans, use "Sta-Bil", a gasoline stabilizer. It can extend the shelf life of gasoline to about a year. I have a few gas cans that I use for my rider mower and emergency generator. I date them and if not used for 9 months, I use it in the car and refill (and re-date) the gas can.

                Comment


                • #9
                  Re: 120 volts...but low wattage

                  I use StaBil all the time and when I find a tank with dirty or stale fuel, I tip it out and add fresh gas along with some acetone.

                  Comment


                  • #10
                    Re: 120 volts...but low wattage

                    acetone can be very agressive on some parts, use it with moderation,
                    1/4 oz acetone to 1 gal. would be the max I would put in.

                    acetone is the active ingreadent in nail polish remover, don't spill it on the paint, and in larger percentages It can be damaging to soft parts,

                    acetone does not stablize the fuel but would work for a varnish or a cleaner of the fuel system.

                    Stabil and PRI-g are fuel stablizers, but the best practice is to drain out and run dry, IMO
                    Push sticks/blocks Save Fingers
                    ~~~~~~~~~~~~~~~~~~~
                    "The true measure of a man is how he treats someone who can do him absolutely no good."
                    attributed to Samuel Johnson
                    ~~~~~~~~~~~~~~~~~~~
                    PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

                    Comment


                    • #11
                      Re: 120 volts...but low wattage

                      Originally posted by wbrooks View Post
                      If this is a 220V capable generator then it is functioning correctly.
                      It will produce 2000W on each 'side' @ 120V. When you add the two halves of the generator together you get 220V @ 4000W
                      Wow....shortest answer...but you're right. I plugged my KillaWatt into one outlet then plugged two 1500 watt heaters into my KillaWatt. I thought the two outlets on my genny are wired the same as a household outlet and one outlet would supply all 4000watts. Ok why did I do this test?
                      I just read a thread stating that my 220v 3/4hp deep well pump only needs about 550 watts to pump water. My 4000 watt genny won't fire up the pump. Perhaps I am wiring my pump up wrong? Or does the fact the pump is so far down (275 ft.) put so much load the pump (from 550 watts to over 5500 watts) on the pump that my genny cant fire it up?

                      Comment


                      • #12
                        Re: 120 volts...but low wattage

                        894tom

                        WBrooks brings up a very good point
                        The windings are normally series connected and if you put your load only from say L1 to Neutral (1 side of 2) then you can only expect about 1/2 of rated output unless you have a special switch that connects them in parallel for full power at 120 Volts. A good test would be to connect (1) 1500 Watt heater to one receptacle and another to the other receptacle assuming you have (2) 120 Volt receptacles. In some cases they will split connect one duplex (can have 2 plugs in it) receptacle where the top and bottom are connected differently.

                        Please note the special switch may say something like FULL POWER and then have 120/240 and also 120. To get any 240 Volt output you can't have such a switch in the 120 only position.

                        Now getting to your well pump, you really should have it connected up for 240 Volt operation even when running on line power. How is it setup as of now?

                        A 3/4 HP submersible pump that's say 275 feet (inlet) below ground and the water level is say 150 below ground and you have 50 PSI pressure in your storage tank = Very hard starting and takes many times the running current to start it up. There's no way you'll start such a pump if setup for 120 Volts even when powered by a good 5000 Watt generator unless the generator can supply full output at 120 Volts and also you'll need some heavy wiring to prevent too much Voltage drop.

                        For now, please let's get the generator working as it should. The pump can be project #2.

                        Test: Unless you have a special KillAWatt with a 120/240 Volt input you will be limited to just using it on about 120 Volts. You can plug it into one of the 120 Volt receptacles and then plug in one of the heaters. Be sure to also plug the second heater into the other 120 Volt receptacle on your generator and then try to run both heaters. What happens? Try shutting off only the heater plugged into the KillAWatt. Now what are your readings? How about if you shut off the heater not plugged in the KillAWatt? What are the readings with only the KillAWatt plugging into receptacle #1 and then into #2 with no loads?


                        Hint: Do you know someone that's seriously into electrical or electronic work? If yes, have him/her bring over a multi meter which can read about 0-300 AC Volts and connect it to L1 and L2 of the 240 Volt receptacle. Then try the heater loads. What readings do you get for no load, one heater, then the other heater and finally both heaters running? Will your KillAWatt provide frequency readings? Some models will and some won't.
                        Last edited by Woussko; 09-27-2009, 05:35 PM.

                        Comment


                        • #13
                          Re: 120 volts...but low wattage

                          there is running watts and starting watts, and they are not the same, an electrical motor can easily take 3 to 5 times the running watts to start,
                          you may have noticed that at times lights may dim when a electrical motor starts, that is the starting load causing a voltage drop on that circuit, or building, depending on the wiring and its size,
                          Push sticks/blocks Save Fingers
                          ~~~~~~~~~~~~~~~~~~~
                          "The true measure of a man is how he treats someone who can do him absolutely no good."
                          attributed to Samuel Johnson
                          ~~~~~~~~~~~~~~~~~~~
                          PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

                          Comment


                          • #14
                            Re: 120 volts...but low wattage

                            [QUOTE=Woussko;254716]894tom

                            A 3/4 HP submersible pump that's say 275 feet (inlet) below ground and the water level is say 150 below ground and you have 50 PSI pressure in your storage tank = Very hard starting and takes many times the running current to start it up. There's no way you'll start such a pump if setup for 120 Volts even when powered by a good 5000 Watt generator unless the generator can supply full output at 120 Volts and also you'll need some heavy wiring to prevent too much Voltage drop.

                            /QUOTE]

                            I tried pumping on the 220 side not the 120 side. I dont understand that even at 5 times the 550 watt load of a 3/4 pump (2750w) it still wont start. Does the fact that the pump is 275 feet down make it that much harder to start pumping? I am pretty sure my genny is running up to par. I put the two 1500w heates on it and she did lug down, but my killawatt showed both 120 sides working as they should.

                            Comment


                            • #15
                              Re: 120 volts...but low wattage

                              The math is a bit off for the 550W.
                              1 HP is 746 watts so 3/4 HP is 560 W, problem is there is no power factor or efficiency in that calculation, you could easily be in the 700-800W range for running and a full 6 to 10 times that for startup depending on type of motor and length/size of wire to the pump. I would suggest that a generator with a minimum of 6500W startup would be required to start your pump.

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