My Koehler commander 7.5 kW genset starts great but begins to shake and run rough after a few minutes. I have a porcelain fuel filter in front of the regulators and it's clean. Any suggestions? Thanks.

I don't have a KOHLER. But, my diesel powered 10KW genset would not stay running when I had porous, deteriorated fuel lines. The fuel pump for it is really tiny -- not powerful enough to supply the engine if air is getting mixed with the fuel.

Richard, I have a 6.5 on the boat, a 4 cylinder engine, the same was used on the 7.5 with a different carb if memory serves. Two questions come to mind, easiest first, do you have a decent load on the genny? I am thinking above 50%. Second is not so easy, the fuel pump can be iffy, a perforated diaphragm or diaphragm that is soft, that would allow it to run but not deliver sufficient fuel to keep the carb bowl filled. FWIW,
Tim

Is your Koehler a Diesel? If so the small fuel line pump is just a “lift” pump that supplies the high pressure pump on the engine. Ours is a 4 cyl Kubota. This pump can be purchased at most Auto Zones for about $40, sometimes less. The model is not important only that is produces about 6gpm and runs off 12v. Because of the age of the lines it is best to drop the tank and replace all rubber connections. Ours has rubber from the tank to the metal line attached to the frame rail and then rubber from the metal line to the lift pump. The tank is held by a couple of steel straps that are not difficult as long as you have something to support it. Use antisize when you replace the bolts. On some coaches there is access under the carpet in the front of the kitchen.

Diesel, Gasoline or Propane??

Richard has propane. They are camping and may not have WiFi

as i played with the genset, I noticed that it ran great with no load but the minute I flipped the breakers on, it started to run really rough. Would it make sense to flush the regulators out with carb cleaner or gasoline?

I don't have experience with lp units but, big guys in the pool hall tell me the carb stays clean, but pressure regulator may suffer age but first and always check ignition side. Plugs, particularly gap and condition, wires, replace because they are pretty cheap. Clean the cap, dress the rotor and points.
Tim

An internet search suggests that the slip rings can cause this problem as well .

http://forums.goodsamclub.com/...31112/print/true.cfm

http://blog.goodsam.com/cleani...and-brushes-part-19/

Also check the governor rod for ease of movement , i read that they can stick from getting dusty.

quote:

Originally posted by Richard_Muise:
Would it make sense to flush the regulators out with carb cleaner or gasoline?

NO The propane vaporizer has diaphragms that can be damaged by aggressive cleaners. If your vaporizer is mounted so the drain can be opened and the oily substance (used to add odor to the propane) can be drained that is the first step.

Second, check the spark plug gag, should be no more than 0.018", yes closer than for gasoline but propane is harder to light. The diaphragms may have failed in that case, a person familiar with vaporizers and have the proper equipment to rebuild and calibrate must be used!

Well sportsfans, the genset is dead! ordered a 5500 Onan brand new today. Frig it. I ve had problems with this one for three years and my patience wore thin. ho needs money anyway?

While you are on a shopping spree buy new lines too (if you going propane). On our Beaver they started leaking from old age

generators need to be "exercised" at regular intervals, under load, or they die. A former owner of my FT neglected to do that, resulting in $ten coach buck dynamo replacement. What Dave Ramsey calls "Stupid Tax"
come to think of it .... I better go out and run mine right now