Question about Coleman Powermate Premium Plus 6250W Portable Generator
I have had this unit to the two shops. The Briggs and Stratton repair shop hooked it up to a test load and, as I told them, the engine slows when the load is increased. At no load, it runs at the prescribed rpm and puts out 120/240 @ 60 hz but as the load is increased, the engine slows and the voltage drops. The shop had adjusted the spring plate and seamed to think that the governor was working properly because is held the speed at no load. They have suggested that I take it to a generator shop shop, which I had previuosly done and was told that the generator played no part in the speed regulation problem i.e mechanical governor. If it is the governor, how does it function and can it be serviced/adjusted easily? Is it internal to the crankcase? Are there any simple tests?
While attending college I worked at a tool rental center and learned a great deal about matching generators to customer requirements and troubleshooting customer owned units. There are simple tests that you can perform, however, first some info on what to expect from a generator. Most generators are overrated and under powered. You should only expect to get about 60 - 75% of rating. Example, a commercial honda 5000w generator has an 11hp motor that can only produce about 9.5 hp at 3600 rpm. If a customer needed 5000w of power, we would rent them an 8000w generator because as the generator is loaded to max the voltage will drop. You generator will probably only provide steady voltage ex. 115v at 60 cycles to about 3500w then voltage will begin to drop. New generators have automatic voltage regulator that varies the power to the armature increasing/decreasing the power of the magnet. These voltage regulators suffer a high failure rate and are expensive. If your generator is not giving you 3500 watt at 115v 60 cycles your engine may have a few problems and your power generator end may need tweaking. (I would not expect to achieve 5500w at 115v with briggs 10hp) .
The governor is about 2 inches in diameter and turns off the cam gear inside the engine. It is flyball type with two or three small arms that react to rpm. The faster the engine turns, more force is applied to the governor arm to reduce engine speed. Easy to test, with engine running use finger pressure against the arm to increase speed and you should feel a greater resistance as the engine speed increases. Another simple test, remove air filter to expose butterfly inside the carb. Move the governor arm and check that the butterfly opens fully. If it does not open fully linkage and governor is not set correctly. Next, start engine and load generator up to max and check that butterfly opens to full as the load increases. When the butterfly opens all the way under load the engine is at max. Add up the wattage of all the tools/appliances you used to load the engine to get an idea of max load . Lets assume that the shop adjusted the governor properly, if the governor was not working the engine would over rev. and damage would occur. As you were told the governor spring controls speed and can be adjusted somewhat by bending tab or adjustment screw. But a review of your generator manual or that series of briggs engine will show that there are several governor springs available and different placement holes on the governor arm to attach the spring that will change the power curve. Pulling on the spring can only do so much, however changing the spring to different gauge /turns/material or differnet location on the governor arm will cause the engine to perform differently. These springs are sold thru briggs dealers by part number for your engine. This would be considered tweaking to get a different power curve.
Now for the generator. Some generators have a capacitor incorporated in the windings. This capacitor must measure within 95% of rating. Remove from circuit for testing. Finally look very carefully at the commutator rings for any evidence of brush bounce. If the brushes do not perfectly seat you will lose power. If your generator is brushless you can only hope that the diodes are within spec. because it is too difficult to test them. They also must be removed to test. Finally if your generator has an automatic voltage regulator the only test would be to replace with a known good part. At the rental center we stocked spare parts so that we could quickly find fault. There is soo much to learn and the life too short. I hope this helps good luck, please email your questions.
Posted on Dec 27, 2008
The governor on you engine is mechanical and the problem should have been fixed by the generator techs unless the company is a joke. You can't work on genset and not be able to understand and adjust engine governors. The other solution posted was very good, but normally on a briggs unit the external spring that forces against the governor fails, breaks, holding arms are bent, or the carburetor is dirty and needs to be cleaned and inspected. I would push against the governor arm on the engine and check to see if it resists against you pressure. Also if you run the engine up and let go of the governor arm it should not droop(slow down) much below its normal speed. If it does resist you know the internal components are working. Then check to make sure that you have the external spring on the governor arm. If it is there look for an adjustment. The spring will either be connected to a plate that has an screw to adjust the spring tension, or holes that you can place the spring in to set the tension. Play around with that first. If you still have the same problem its probably coming from the carb. Little carbs easy get dirt in there ports/jets, and if you rarely run your unit the fuel that is left in your carb will go bad and clog up your primary jet. Remember when adjusting your governor that any changes will effect your engine speed and will have to be adjusted back to 60-62 hz with your carb or governor speed adjustments. I recommend a little over 60hz so that under full load you unit will be able to handel it.
Posted on Feb 03, 2009
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Posted on Jan 02, 2017
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