MEP-803a Falls on its face under light load

[eatont9999]

Hi guys,

I finally got my generator wiring finished to the house but I have a problem with the generator under load.

Any larger power draw like the AC or water heater puts the generator flat on its face. It almost stalled out several times while I tried to jockey the load around. It runs the lights and a window AC unit at the same time but I can't add anything else or it bogs down to where it browns out.

When I close the load switch, with the house breakers closed, it bogs almost to a stop. It does not smoke out the exhaust or try to increase fuel to the engine. The % load gauge sits all the way to the left, not sure why, but the most I saw it read was 20%. It's like the governor isn't working. I can set the idle RPM but that does not help this situation.

I really need this unit to run the house AC system, well pump and lights to be effective.

Has anyone else experienced this kind of problem before? I'm not sure where to start.

 

[98G]

Have you added up your total amperage load?

 

[Light in the Dark]

Yes, figuring out what you are actually asking the machine to produce, is the baseline. Look at all of the appliances you want to turn on and find their data plates/stickers showing energy use on them. Folks can eat up power faster than they realize (especially with high draw items during their initial ramp).

 

[Light in the Dark]

Also a silly question... but what voltage setting are you running at?

 

[DieselAddict]

In addition to good info above, I strongly recommend having the generator load tested to verify you have a properly running machine.

 

[justacitizen]

all of the above is in order. also when you throw the whole dead house on line at once you are starting all of the loads AC/wellpump/freezer/and on and on all at the same time. try unplugging or turning off the cyclic loads and bring them on one at a time.

 

[Ray70]

I agree with all above and especially DieselAddict. You really need to determine if the machine itself is working correctly or if your house load is excessive at startup. You may have issues with dirty switch contacts causing you to think you have a 20% load when you really have a lot more, or you could have governor, lift pump or injector problems etc.
You should perform some kind of load test, even if its as simple as adding on loads of known power consumption. A $12 water heater element in a 5gl bucket of water ( wired up in a safe manner of course ) is a cheap down and dirty test ) Or even things like hair dryers and spot light bulbs of known wattages can be used, just do it in a manner that you can control the exact wattage you are using and see how the %load meter and governor react as you incrementally increase the load.

 

[eatont9999]

With the house at idle, ac running, pool pump on, fridge, a few lights and a window unit, I'm seeing right about 25A per leg on the load terminals in the transfer switch. I run it at 240V, so that is 50A total draw.

Startup is something that is going to be an issue. With everything off except for the AC system, it couldn't even start the central air system.

I think what I will do next is shut everything off but the stove and see how many amps I can draw from the gen before it falls below 55Hz.

 

[Light in the Dark]

Make and model of the AC you have? If you can't find the data plates on it for energy, I can probably do so online to see what the behemoth is asking you for.

 

[devilphrog]

Once you establish operational serviceability of the genset, you should probably start reading this thread

 

[eatont9999]

The AC condenser unit is rated at 25 RLA and 115 FLA. The air handler in the attic was pulling a total of about 4 amps with nothing else in the house on.

I was able to load the generator up to 56 total amps and it maintained over 60Hz, so I think the gen set is doing its job. The % power gauge is obviously got issues as it did not go over 25%, even with the set running under more than full load. It really does not like being hit with inductive loads. Sometimes when it falls flat, I have shut off the load and cycle the disconnect switch on the gen for it idle back up.

 

[devilphrog]

I think you're FLA/RLA amps are what's drawing down your unit on startup, and you may be a good candidate for a Soft Starter. However, are you getting a Short Circuit light or Overload light warning? Do the fault lights press to test correctly? When was the last time you used contact cleaner / DeOxit to clean out S6 and S8? Also, have you tried a quick test in Battle Short to see what happens?

 

[eatont9999]

I think you're FLA/RLA amps are what's drawing down your unit on startup, and you may be a good candidate for a Soft Starter.

However, are you getting a Short Circuit light or Overload light warning?
None that I have seen.

Do the fault lights press to test correctly?
Yes, they all light up.

When was the last time you used contact cleaner / DeOxit to clean out S6 and S8?
Never.

Also, have you tried a quick test in Battle Short to see what happens?
No, I have not.

I have edited the above to answer your questions.

 

[Daybreak]

Howdy,

The generator does not automatically maintain 60Hz. It would be best if you see what your standard loading is, and turn the throttle up some to a good 60Hz. Verified with gauge and a external multi-meter reading.

Say your standard load is 40 amps, which would be around a 80% usage, set the engine here to 60Hz. That also means when no load is applied, you might be around 62Hz.

 

[Bmxenbrett]

Have you done all the normal maintenance items like filters and fluids? You can also reset the fuel pumps on the rack by turning them. I suggest you read the TM on how to do this. I would do filters and fluids before anything else. Then get your self 3 5kw electric dryer elements to stop risking your house appliances on a generator you know to be faulty.

Dryer elements are about $15 each and can make a load bank from 1.6kw to more than your set can handle with only 3 of them

 

[eatont9999]

Howdy,

The generator does not automatically maintain 60Hz. It would be best if you see what your standard loading is, and turn the throttle up some to a good 60Hz. Verified with gauge and a external multi-meter reading.

Say your standard load is 40 amps, which would be around a 80% usage, set the engine here to 60Hz. That also means when no load is applied, you might be around 62Hz.

I had set it to 62-63Hz at idle. I will have to adjust that at 80% load, like you suggested.

 

[eatont9999]

Have you done all the normal maintenance items like filters and fluids? You can also reset the fuel pumps on the rack by turning them. I suggest you read the TM on how to do this. I would do filters and fluids before anything else. Then get your self 3 5kw electric dryer elements to stop risking your house appliances on a generator you know to be faulty.

Dryer elements are about $15 each and can make a load bank from 1.6kw to more than your set can handle with only 3 of them

I did the maintenance items well before I hooked the set up to the house. I have an aux pump adapted to run as the primary pump, so that could be causing fuel flow issues. I will hook up my 12v fuel pump externally and see if that makes a difference - after I get some dryer elements.

 

[eatont9999]

I built a load bank today and tested the generator on it. I can run one dryer element and it pulls 22-25A on each leg. I had one that would pull 27A when I switched it on and it bogged the set down. It seems like when it bogs, the RPM just keeps going down until maybe 1000RPM and it just sits there like that. If I switch off the load quickly, it will bounce back. If I wait more than a few seconds after it bogs, I have to cycle the disconnect switch for it to idle back up.

I swapped the fuel pump with an externally powered 12V pump and ran the set again to test it. Same exact symptoms as before. No change. I also used fresh fuel from an external source.

I measured the temp readings on the exhaust manifold. The cylinder closest to the fan read 250F and the rest were right about 300F.

 

[jamawieb]

The cylinder reading 50 degrees lower is the problem. Swap the injectors around and see if the temperature decreases with the injector. If not, swap the pumps and then you'll know if its one of those.

 

[eatont9999]

Here is the load bank.