1998 Onan MicroLite 4000 Weak SPARK
I have a 1998 Onan MicroLite 4000 Model No: 4.0 KY-FA/26100H that wont start. She turns over, a little hesitant to turn over but does. It has spark but it is very weak, I believe so weak the fuel p...
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Usually the generator is started from the house battery. If you have a weak battery or a poor connection to it, running the (main) engine will engage whatever sort of battery combiner/isolator system you have and the generator will be using both electrical systems to start.
The generator starter needs quite a bit of current, somewhere around 100A. It doesn't take much to cause a voltage drop at 100A that is all but unnoticeable for typical RV usage.
The starter should be able to easily and energetically spin the engine. If it struggles to get over the first compression, besides the ground and power connections it could also be a bad or disconnected brush in the starter motor. The starters are permanent magnet DC motors, with four poles and four brushes, and if one of the four brushes is not working they will still operate at about half power. In my case, that was just barely enough to get over the compression cycle...most of the time...until it didn't on a cold day and I burned out a couple windings in the starter trying too long.
I don't think you have a spark issue, but rather a carburetor issue. It seems the engine dies when the throttle is opened, which may mean a clogged main jet possibly? It looked to me like the governor was attempting to govern the engine speed properly, i.e. it moved the throttle in response to engine speed changes, but the engine did not respond properly.
The generator starter needs quite a bit of current, somewhere around 100A. It doesn't take much to cause a voltage drop at 100A that is all but unnoticeable for typical RV usage.
The starter should be able to easily and energetically spin the engine. If it struggles to get over the first compression, besides the ground and power connections it could also be a bad or disconnected brush in the starter motor. The starters are permanent magnet DC motors, with four poles and four brushes, and if one of the four brushes is not working they will still operate at about half power. In my case, that was just barely enough to get over the compression cycle...most of the time...until it didn't on a cold day and I burned out a couple windings in the starter trying too long.
I don't think you have a spark issue, but rather a carburetor issue. It seems the engine dies when the throttle is opened, which may mean a clogged main jet possibly? It looked to me like the governor was attempting to govern the engine speed properly, i.e. it moved the throttle in response to engine speed changes, but the engine did not respond properly.
