Re: oil injection info please
i have an 1986 xr2 150hp with oil injection. everything to deal with it has been taken off tanks and all
Is the pump gone too and a block-off plug installed in the hole? The Black Max uses an external oil tank mounted in the boat, except for a little reserve tank under the cowl that will run the engine for 30 minutes at WOT, and it uses variable ratio oiling. The fuel/oil ratio varies from about 100:1 at idle to around 40:1 at WOT and full load @ 6,000 rpm.
Mercury QuickSilver mixed at a 50:1 ratio is fine for "average" operation. If you're a basser and running it at WOT consistently I'd drop it to 40:1. As to your question about will it hurt the engine? - no - as long as you take some precautions. Back when this was a popular thing to do gasoline didn't have alcohol in it, and alcohol presents new problems for marine engines that use a pre-mix. More on that below.
What you're seeing here is due to the history of the early V-6's - the Black Max's had problems with the oil pump due to failures of the nylon drive gear in combination with people turning them over 6,500 rpm. It was a popular item to remove on those engines because of the oil pump gear failures, and Mercury made a complete kit to remove it.
If you plan on running the engine alot it's worth it to fix the oil injection and put an aftermarket steel drive gear in because it doesn't take long to recover the $155 pump cost in the cost of expensive synthetic oil.
If you just use it a few weekends a summer, then it's not worth it and you may as well leave it in pre-mix mode. If you pre-mix just make sure you use a good synthetic oil that will mix with ethanol blended fuel - just about all gasoline has ethanol in it these days and petroleum-based two-stroke oil does not mix with ethanol.
Modern alcohol blended fuels are also hydroscopic, meaning they will absorb water - even atmospheric moisture - and hold it in suspension. Even synthetic oil does not mix with water, and if you leave a pre-mix sit for two weeks it becomes "stale", meaning that the solvents in the two-stroke oil evaporate and cause some seperation of the oil from the fuel. With little boats with a 6 gal carry-on gas tank this is no problem because you can shake the can and adequately re-mix the oil and fuel. However, in a larger boat with a built-in tank, trailering the boat to the lake is not adequate to re-mix a "stale" pre-mix. So if you have a built-in 20 gallon, or whatever, gas tank I recommend leaving the lake with the tank near empty, keep the vent shut during storage, and before going to the lake again re-fill the tank with fresh fuel and oil.
Again, back in the day when we had "real" gasoline, pre-mixing was not a problem. Modern oxygenated fuels are crap in comparison to the gas you could buy when your outboard engine was new. So it takes a few extra pains to deal with it when using pre-mix.
--
Chris
