'00 Mercury 90hp, oil injection still works, time to replace it with premix or replace worn parts?

[wn6ngp]

I've got 00 Mercury 90hp ELPT 2 stroke. s/n ot087666. About 500 hrs on it. No significant problems with it, no overheat, runs perfect staying on ethanol free. My question is should I do something with the oil injection mechanism? What I can see of things everything looks ok. Those small plastic hoses for fuel and oil are hard but seem to be ok. I can't really see the hose that goes from the oil pump to the oil tank but no signs of leaking elsewhere. Is the gear on the oil pump that is driven by the crank on its last legs? Most old school motors I see like this have long ago gone to premix. I've rebuilt the fuel pump one time. I'd hate to lose this motor by hanging onto the auto oiler too long.

 

[Faztbullet]

Motor has bottom driven gear that rarely fails. Replace hoses with some clear polyurethane fuel fine and go fishing

 

[Texasmark]

At 10 years of age I decided to go to premix with my '02 90. Just felt like doing it and figured just one less thing to worry about. The other thing was that I boat seldom and the Mercs in my life like a lot of fuel to light off the first time after sitting.

If the crankshaft is turning the oil is pumping whether fuel has made it to the combustion chamber or not. First starts after sitting, and I know how to start and engine, always resulted in a big smoke screen and wobbly operation until the oil was burned off the combustion parts.

Premix solved both problems. The change was simple. I pulled out the oil pump, removed the shaft-gear and put it back together. Took about 15 minutes. I then made a note on my boat at the fuel inlet to remember to premix.

Fast forward. I have a different boat now with a '02 115. I got tired of what I said earlier and just recently changed to premix. Nothing wrong with the engines. My avatar is my 90 on a 17+ foot, stepped hull a Fishmaster, aluminum BB running right at 50 with a 24P Ballistic SS. The current boat, a Crestliner 1750 Fish Hawk, will hit 50 with a 22P Ballistic SS 3 blade prop on a cool day with just me. If there was anything wrong with either engine, I wouldn't get the top end I get.

 

[QBhoy]

Always a tough one this. But from what I know of these particular engines and similar…as long as the delivery lines, fittings and fixtures are kept well maintained, you should be good.
Should she be of the larger v6 type…get rid of it asap. That’s a different kettle of fish altogether! If you want some back up along with keeping the injection system..I know guys that add a little oil to their fuel just as a back up measure. Something into the triple digits to 1 ratio perhaps.

 

[airshot]

Can only go by what my motor repair guy has told me. Been going to him for many years and have never been steered wrong. I do most of my own work when possible but use him when things get to deep for my skills. Also a personal friend of many years so I trust his judgement. He claims in his 30 plus years he has never saw an engine failure from a Merc oil injection system yet. Maintenence is a must by keeping oil lines in good shape and a clean fuel system. The VRO system is another story, but I was concerned when I bought my first oil injected Merc two summers ago. He has instilled confidence in me that they are good to go. He says he has junked Merc motors for many different reasons, but the oul injection system is not one of them.
You can take this for whatever it is worth to you, but my 1992 has never had an oil injection issue...so far.

 

[QBhoy]

Can only go by what my motor repair guy has told me. Been going to him for many years and have never been steered wrong. I do most of my own work when possible but use him when things get to deep for my skills. Also a personal friend of many years so I trust his judgement. He claims in his 30 plus years he has never saw an engine failure from a Merc oil injection system yet. Maintenence is a must by keeping oil lines in good shape and a clean fuel system. The VRO system is another story, but I was concerned when I bought my first oil injected Merc two summers ago. He has instilled confidence in me that they are good to go. He says he has junked Merc motors for many different reasons, but the oul injection system is not one of them.
You can take this for whatever it is worth to you, but my 1992 has never had an oil injection issue...so far.

He can’t surely have ever come across Ann old mercury v6 2 stroke perhaps. Famous for the drive shaft failing.

 

[flyingscott]

Can only go by what my motor repair guy has told me. Been going to him for many years and have never been steered wrong. I do most of my own work when possible but use him when things get to deep for my skills. Also a personal friend of many years so I trust his judgement. He claims in his 30 plus years he has never saw an engine failure from a Merc oil injection system yet. Maintenence is a must by keeping oil lines in good shape and a clean fuel system. The VRO system is another story, but I was concerned when I bought my first oil injected Merc two summers ago. He has instilled confidence in me that they are good to go. He says he has junked Merc motors for many different reasons, but the oul injection system is not one of them.
You can take this for whatever it is worth to you, but my 1992 has never had an oil injection issue...so far.

Seriously? The plastic drive gear is prone to failure on the V6s. Especially after an overheat.

 

[airshot]

Seriously? The plastic drive gear is prone to failure on the V6s. Especially after an overheat.

That was a motor I never questioned my mechanic on, I had bought a 40 classic with oil injection, so our discussion was primarily smaller motors. I made the assumption the great reputation was for all Merc outboards. Just goes to show...never assume !!

 

[racerone]

I have seen a few of the plastic gears that had failed on the V-6 and 3 cylinder motors too.

 

[flyingscott]

I agree the 3 and 4 cylinder rarely fail. the V6s that's a different issue. I have a 75 and 90 hp I am rebuilding and they will get their oil injection put back on.

 

[electricjohn]

35 years and 1600+ hrs. on my oil pump. Replaced hoses with clear Tygon about 20 years ago and oil tank about 15 years ago because oil alert float switch failed.

 

[workboot]

I have seen a few of the plastic gears that had failed on the V-6 and 3 cylinder motors too.

I have 2002 200 hp efi , should I replace my gears and are they sold separately, as I could only find the whole pumps. Thanks

 

[racerone]

On many of them the plastic gear is on the crankshaft.-----Near total teardown required to replace it.

 

[workboot]

On many of them the plastic gear is on the crankshaft.-----Near total teardown required to replace it.

ok thanks , I guess I won't be changing that !