Hi MRMELCHOR. Welcome to the forum. There are two different generators available. Do you have the more common unit with built-in voltage regulator, (bolted on the back), or do you have an external voltage regulator? The built-in unit will have a large plug on the side near the back, with two fat black wires with orange stripes.
With that large plug, it is extremely important that it not be unplugged. Doing so will degrade the connections and lead to them overheating and burning. Rebuilt generators actually come with a new plug already installed. You are to splice the wires and use heat-shrink tubing, and not remove the plug.
Besides that, I think the secret here is your observation that you can drive a short distance before the warning light turns on. That means the problem is intermittent. If the generator was tested during a time period when the problem wasn't occurring, it would test good. It needs to be tested while the problem is occurring.
When the warning light turns on, there is a test you can do while the engine is still running. This only applies if you have the voltage regulator bolted to the back of the generator. It is held on with four small bolts in a rectangular pattern. Between two of them are two more bolts that are attached to the internal brushes. One was originally covered with a plastic cap but it might have fallen off by now. The exposed bolt is the test terminal. It might help to look at another generator that's off the engine so you can see the back more clearly. The test terminal is labeled "Ground here to test". When you use a piece of wire to ground that bolt, watch to see what happens to the headlights, or use a voltmeter to measure battery voltage. If the voltage goes up to around 15.0 volts or higher, or the headlights get brighter, the voltage regulator is defective. It can be replaced separately, and is the most likely suspect because the electronic circuitry is prone to failure when it gets hot. That would coincide with it working ok for the first few minutes.
Monday, April 26th, 2010 AT 9:58 PM