1993 Mercury Oil Injection Bypass

[coppercobra]

Newbie here, - regarding oil injection.

Am I able to block off the oil-feed to the fuel line, and re-route that oil outlet hose to the top of the tank to bypass the oil injection, and then run pre-mix?

*My boat came with this motor, has a fuel filter by the transom, checked the drain valve on the filter, and it was full of premix, the bow tank was also filled with premix (75L), im not sure what they have done regarding the oil injection, also the in-line fuel filter had premix in it also, im not sure if they have a block off plate installed. The oil reservoir was 1/3 full. boat was just river tested at 5250 rpm by a local shop as they had it in for service before the sale. I have a copy of the receipt. They did plugs, starter, stator, and lower unit oil. (Boat was serviced due to no spark).

Runs great now, but I am still baffled as I would like to enjoy it this weekend and want to make sure I am taking all the proper steps to ensure longevity of this motor.

Any insight is much appreciated.

Thanks

 

[tpenfield]

:welcome: to iBoats . . .

Not sure about re-routing the "oil outlet hose", but many folks have circumvented the oil injection and just running the 50:1 pre-mix by adding 2-cycle oil to the gas tank before they fill up, etc.

 

[Texasmark]

You didn't say what HP. I had a 2002 90 HP and after it turned 10 years old, I decided I wanted to premix. All I did was to first add 50:1 to my fuel tank and run my engine long enough to know that I had run premix through it......oh and mark "ADD OIL" adjacent to my fill port for my fuel tank.

I then pulled out the 3 screws holding the oil pump in place, disconnected one fuel line to it for removal convenience, tilted it back so I could get to it, pulled out the geared shaft that drives the pump, put it back together and never looked back. The oil tank had oil in it from my last injection running and that stayed there and kept the oil level alarm quiet.

So last year I buy a 2002 115 HP and it still has the injection and I have no urge to change it. Just some days you get up on the right side of the bed and others the left I guess. I still sleep ok either way.

 

[coppercobra]

My bad, it is a 125hp.

Pardon my terminology, but by oil outlet im meaning the hose running from the oil tank to the fuel system.

I had come across another page where someone had drilled a hole in the top of the oil tank, ran the hose up to it, essentially cycling the oil back into the tank rather than the fuel system, then running 50:1 mix.

Wondering if this is an option until the block off plate arrives?

 

[Texasmark]

Backing the truck up, you may be outside my area of support. My manual starts with 1994 engines which have the oil tank under the engines cowling....on board storage. I had a 1988 I6 with a separate, boat mounted, oil tank which mixed oil with the fuel and was sent to the engine. It has been many years since I had that boat and I have forgotten the particulars. From what you say in your latest response, it appears that the 1993 engines still had this type of oiling system.

As a general comment, boats ran on premix decades before the advent of automatic, variable ratio, onboard oil storage and pumps. I would assume that it would be no problem in bypassing that setup and plumbing directly from your fuel tank, through a squeeze (priming) bulb directly to the engine's fuel inlet, having first premixed the fuel in your fuel tank and run some of the premix through the engine.

 

[coppercobra]

So what I ended up doing was removing the reservoir, oil pump, removing the gear, re-installed the oil pump, blocked off the inlet and outlet on the oil pump, and ran a new line from the fuel pump.

This was advice from a local marine shop. works great.