run out of gas with direct oil injection

[tugboat80]

I have a 1987 90hp Mariner, OB229356, 3 cyl 2 stroke with Direct OIL Injection with 1 gallon tank. The carburetors feed from an aluminium gas tank of 20g. The gas gauge is not working. If I run out of fuel while on an outing and switch to an auxiliary tank, Will I cause problems in need of immediate fix? Problems such as oil fouled plugs, air in oil system, oil in cylinder causing hydro-static lock? I am aware that run out of fuel is not desirable because of lack of lubrication. Should I pre mix the auxiliary tank to ward off interruption of oil flow to the power head?

My gas gauge is wired in connection with the tachometer which is working but the gauge itself does not. I have become wary of boat shops at hundreds of dollars per hour on such repairs.

 

[racerone]

Re: run out of gas with direct oil injection

I believe the oil is injected into the fuel line just before the fuel goes into the carburetors.--------So when you run out of fuel and prime the bulb you are now filling the carburetor bowl with straight fuel.-------Some would say that is a disaster waiting to happen !----In reality when the motor runs out of the mixed fuel then the internal parts are all coated with oil.----It has to be because that is how oil lubricates parts.-------So on initial start-up you would be running with straight gas until oil is injected again.------So you let it idle for 5 minutes or so and it has plenty of lube until things are back to normal.---------Just don't like the idea ? ---what does your manual say to do ?

 

[CharlieB]

Re: run out of gas with direct oil injection

I don't know of any older motor that had oil directly injected , they all injected the oil directly into the fuel stream immediately before the carbs.

The primer buld pushing fuel thru the injection Y-fitting does pick up a small amount of oil. It shouldn't be a problem.

If you are ever concerned that you think your oiling system is not functioning properly you can safely add oil to the fuel tank(s) at a 50:1 ratio until the motor is serviced.

Extra oil will only cause a bit more smoking and may shorten the lifetime of a set of spark plugs. Break-in is often a double mix, which is exactly what I just described, adding oil to the fuel which is in addition to the oil added by the oiler system.

 

[racerone]

Re: run out of gas with direct oil injection

Many older YAMAHA motors do not mix the oil with the gas.-----Oil is injected down stream of the carburetors.

 

[oldman570]

Re: run out of gas with direct oil injection

The 1987 Motors have the oil injection as Charlie has stated. There should not be any trouble on a restart of the motor after having run it out of fuel. It is also best to let the motor idle a few minutes after restart as Racer stated, to let the fuel system get settled in. The oil injection system on the motor is set to mix oil at a 80 -1 mix at idle and to increase it to a 50-1 mix as the RPM's are increased. The motor oil injection on that year motor could be one of two different systems. A manual for the motor can be very helpful for you to understand just how both systems work, and is a cheap investment when work on the motor needs to be done. JMO
Oldman570

 

[Chris1956]

Re: run out of gas with direct oil injection

Wait a minute. What the OP has described is almost exactly what happens when starting the motor after a week or so lay off. During the lay off, gasoline in carbs evaporates, leaving some oil behind. Same as what happens, when you run out of gas, as there is some residual oil in the carbs since the oil injection continues as the motor spins down. Now you reprime with straight gas, just like after the layoff.

 

[Faztbullet]

Re: run out of gas with direct oil injection

If I run out of fuel while on an outing and switch to an auxiliary tank, Will I cause problems in need of immediate fix?

Not at all......