Re: Pre Mix gas with an Oil Injection still hooked up
I just got a boat (that came with the house) with an early 90’s 90 hp Johnson V4, that I have no history on. The previous owner seemed to only perform quick work arounds – so I have little faith he would have fixed a bad oil injection system.
I cant tell if the gas is premixed right now or not, and I don’t want to burn out the motor. So even if I get smoke, I don’t know if it is from a premix or oil injection.
My question is, how bad is it if I play it safe and premix the gas, but also leave the oil injection hooked up?
My thought is, if the oil goes down in the oil reservoir I know the oil injection is working.
Is there a better way to determine if the oil injection is working?
Usually pre-mixed gas has a color to it, depending on the color of the oil used. It seems all the 2 stroke oil I've used lately is blue, fwiw.
Like belairbrian said, I'd also just remove all the old gas (siphon, drain) and start with fresh 50:1 pre-mix. I'd also remove all oil from the oil lines and oil tank and clean the tank (use a turkey baster to remove, if you don't have a better method .... replace filter on end of pickup tube ... swish a little gas around inside it and dump it out to clean it ... let it dry ...leave it empty for now). Then, since you're running fresh pre-mix, you know you won't harm your engine for lack of oil as you check the oiling system, and know that bad gas won't be causing any running problems you might encounter.
Running pre-mix, you can easily do three important oil system checks:
There are two oil related alarms: "no oil" which is a loud beep every second or so caused by a sensor in the VRO/OMS fuel pump (the fuel pump pumps gas and oil both and mixes them). The "low oil" alarm is the same sound but every 20-30 seconds. It is caused by a sensor (float switch) in the oil tank.
Check the "no oil" alarm: Run the engine with the oil system hooked up but the tank empty. The sensor should sense no oil and give you the alarm. It might take a short while since there might be oil in the system near the alarm sensor at first.
Check the "low oil" alarm (you'll also be checking the "no oil" alarm shut off):
Add about 1/2 to 1 quart of oil to the tank. (but not too much ... you just need enough to prime the system and leave about 1/2 quart in the tank after the system is primed).
Disconnect the oil line from the fuel pump, purge the line fully (pump the oil primer bulb until oil flows freely out of the end of the line, pump a lot of oil out (catch it so you can use it later) so you make sure there's absolutely no air in the line, properly re-connect to fuel pump...and do a couple final pumps).
Run the engine.
The "no oil" alarm should quit after a short while since the sensor in the fuel pump should now be getting oil. But the "low oil" alarm should now be heard. It's the same alarm, but at a much slower pace, one beep about every 20-30 seconds. If that happens you can then begin adding oil to the tank, and after the level reaches a certain point (I think it's about 1.5 - 2 quarts?), that alarm should go away.
Oh, put a piece of tape vertically on the tank before you start adding oil, and mark 1/2 or 1 quart increments as you add the oil. Then, when you fill the tank and run the engine, you can roughly compare the amount of oil burned to the amount of gas burned. It should come to approximately 50 or 60:1.
My opinion - if you do the above and it checks out, you have a functioning oil system and can quit mixing 50:1. If not, you have to figure out if you have a bad OMS/VRO pump (the fuel pump which also pumps and mixes the oil) or something wrong with the alarm sensors, etc. Gets a little more complicated, and you have the decision whether to troubleshoot, or simply disable the oiling system and run premix (I much prefer the oiling system having done both for many years - and feel it's worth some time and expense to have it working).
