Ask the Editors: How to Check an Oil Injector
2-stroke plugs tell a story.
There absolutely an easy to perform check: Shut off the fuel line at the petcock, remove the spark plugs, hold the throttle wide open, and crank the engine over.
Grab your flashlight and check inside the spark plug hole – Remember, without a spark plug, the engine will turn over much faster.
Now take a look at the manifold where the oil line enters the head from the reservoir. If the oil pump is working, oil should moisten up at the inlet, eventually forming a drip.
Do keep in mind, though, that a small bore, air-cooled 2-stroke uses VERY little oil. In fact, these reservoirs often only need topping off once a season under pretty regular use. As such, don’t be alarmed if the inlet is merely moist with 2-cycle oil. That’s indicative of functionality.
And though much less scientific, when all other measures fail, it sounds like you’re doing the wise thing in paying careful attention for the machine running lean at the plug. Here’s a chart to reference, your plug looks right in the middle of the OK zone.
Other ways to tell are the machine idling high, running hotter than normal, difficulty starting. Check the exhaust – there should be black liquidy residue inside the can as a result of unburned oil. It should also have the unique aroma (oily) of 2-stroke fumes.
If your tests conclude that the pump is not working, simply detach the entire injector system and mix the fuel around 32:1 in a gas can just like you would a chainsaw or weed-whacker and carry on with peace of mind.
