1992 100 hp oil injection

[bukfevr]

Just bought a 1992 Mercury 100 ELPTO. It has the oil tank under the cowl. I'm leery of the oil injection being 20 years old and having read all the oil injection failure stories. What is involved in bypassing this and going to premix? Can I just pull the oil pump and remove the shaft and reinstall the pump, then replumb fuel line straight to carbs? Or is there some bushing in there like the V6's that's going to work loose with the pump shaft out and wreck the engine? I can't find any block off kit like the V6's have to replace the oil pump shaft. Thanks!

 

[1nebel0]

Re: 1992 100 hp oil injection

Just bought a 1992 Mercury 100 ELPTO. It has the oil tank under the cowl. I'm leery of the oil injection being 20 years old and having read all the oil injection failure stories. What is involved in bypassing this and going to premix? Can I just pull the oil pump and remove the shaft and reinstall the pump, then replumb fuel line straight to carbs? Or is there some bushing in there like the V6's that's going to work loose with the pump shaft out and wreck the engine? I can't find any block off kit like the V6's have to replace the oil pump shaft. Thanks!

I have a 90h.p and had the same issue...real simple....take the line going to the carbs, disconnect it and run it to the top of the tank. I drilled a hole and used a gromet to hold the line...So you are using the pump as a recirculation pump and then premix.. I premix 40 to 1 since I run the hell out of all of my motors...You are correct in regards to the V6 motors as I have the plug that must be used to keep the bushing in place...the good part you can always hook it back up if you sell the motor and not have to look for the parts..LOL

 

[Faztbullet]

Re: 1992 100 hp oil injection

I'm leery of the oil injection being 20 years old and having read all the oil injection failure stories

The bottom driven oil systems rarely fail, that one reason it does not have sensors.... I myself would leave it alone.

 

[gbrowne9]

Re: 1992 100 hp oil injection

i have a 115 2+2 and i disconnected the oil injection. take off the oil pump and remove the drive gear,put the pump back in place.remove the oil line going to the fuel pump,block off the fuel pump end,i used vacuum line plugs[auto store].then remove the oil tank and the linkage from the oil pump to the carbs.premix 50:1.tie strap the vacuum plugs in place.i did this 4 years ago and the motor runs great.you my have to lean out the idle mixture slightly.

 

[bukfevr]

Re: 1992 100 hp oil injection

Appreciate the info. So, if I just pull the driven gear from the pump there is no bushings or anything in this motor to come loose and fall into the engine? If I do that, then replumb the lines, I should be able to reinstall the oil injection at any time by replacing the drive gear, right? If I remove the oil tank, what do I need to do with the 2 blue wires on the tank float? Will I still have the overheat sensor and alarm functional? The main worry of mine is that the only to functions of the alarm are oil level in the motor mounted tank, and overheating. How would a person know if the injection failed before it was too late to save the motor? I like the convenience of it, but it worries me also.

 

[gbrowne9]

Re: 1992 100 hp oil injection

when you pull the drive gear nothing falls in.yes you can reinstall the injection later.disconnect the 2 blue wires at the module on the starboard side of the engine,they should be bullit connectors.the overheat alarm will still work.the alarm would not tell you if the pump fails so you would never know thats why i disconnected mine.after spending 1500-2000 dollars for a rebuild i didn,t want to take any chances.

 

[Texasmark]

Re: 1992 100 hp oil injection

I have a 3 cyl of that engine series. I removed two screws holding the pump to the block, removed the drive gear and little washer, put it back in and did nothing else other than to add a pint to 6 gallons of gas. Been running like that for 6 months or so.

I left oil in the thank to satisfy the low oil alarm. The pump is a displacement pump so if the sprocket isn't turning oil isn't moving. Or, if concerned, do what others have done. I understand the the oiling mechanism is built reliably, but this way I don't have to be concerned with it. Just one less thing to worry about......except adding oil and I put a sign on my boat adjacent to the fill so I wouldn't forget.

Mark

 

[bukfevr]

Re: 1992 100 hp oil injection

OK, so today I pulled the oil pump, removed the driven shaft and reinstalled the pump. Unhooked the hose from oil pump to fuel pump, capped inlet on fuel pump, plugged end of oil line. Unplugged two blue wires to oil level alarm. What about the other line coming out of fuel pump, the fuel pump to crankcase hose? What is the purpose of it? I pumped the gas tank empty and ready for premix. I just emptied the oil tank and left everything else on. Anything I have missed?

 

[Texasmark]

Re: 1992 100 hp oil injection

Oil pump to fuel pump is where the oil mixes into the fuel. The other hoses to the fuel pump are the fuel inlet on the other side of the fuel pump and the crankcase pressure pulse input on the side of the pump. The crankcase supplies alternating pressure pulses to the pump to make it suck and blow.

When you said you unhooked the hose from the oil pump to fuel pump and capped inlet on the fuel pump, lets walk through that.

The fuel comes in the engine through the fuel inlet and goes to the fuel pump and RECEIVES OIL FROM THE OIL PUMP which is pumping oil from the oil reservoir. They are blended before entering the fuel pump. The fuel pump then pumps oil mix up to the carbs. I think the best thing for you to do is to put the hoses back where they were and leave them alone. The pump will not pump oil without the gear.

Mark

 

[reynold460]

Re: 1992 100 hp oil injection

there is a bushing on the bottom of that tube you took the gear out of i would remove it ,i did mine. look on a merc parts page to see it , not sure about the fuel pump diaphrahm the one that mixes oil has 2 holes in it , i removed it and put a solid diaphrahm in instead dont know if i needed to or not haha ., but without a doubt you unhook that piece of junk i tried using mine and it cost me alot of money

 

[bukfevr]

Re: 1992 100 hp oil injection

Reynold, I did take the bushings out of the adaptor tube. I was afraid they might make their way into the engine. You say you used your and it cost you a lot of money, did it quit and cost you a rebuild? That's what worried me.

Mark, I confused myself when I reread my post. Sorry about that, let's try again. Fuel line from tank goes to inlet of fuel pump, still hooked up. Outlet of fuel pump goes through filter to carbs, still hooked up. Fuel pump to crankcase line beside fuel pump outlet, still hooked up. Oil tank to oil pump inlet, still hooked up. Oil pump outlet to fuel pump, unhooked and plugged. Inlet on fuel pump that receives from oil pump, capped and ziptied with vacuum cap. So, the only hose I unhooked was the oil pump outlet to the receiving inlet on fuel pump. Plugged the hose and capped where it hooked on fuel pump. This sound OK? I was afraid if I left this one hooked that the fuel pump might suck air through the oil pump system as I emptied my oil tank.

 

[reynold460]

Re: 1992 100 hp oil injection

yea i bought the motor off a guy that bought it off someone else and never used it so neither him or i knew the oiler wasnt being used ,it didnt have the diaphram with the holes to mix the oil and the 90 degree check valve was locked up couldnt get anything to go thru it in either direction , lucky only cylinder burnt up and i quit running. was idleing the motor fishing and the no 2 piston burnt up had to bore .015 over and replace bearings , rings on other pistons etc.

 

[Texasmark]

Re: 1992 100 hp oil injection

Reynold, Oil pump outlet to fuel pump, unhooked and plugged. Inlet on fuel pump that receives from oil pump, capped and ziptied with vacuum cap. So, the only hose I unhooked was the oil pump outlet to the receiving inlet on fuel pump. Plugged the hose and capped where it hooked on fuel pump. This sound OK? I was afraid if I left this one hooked that the fuel pump might suck air through the oil pump system as I emptied my oil tank.

Sounds good to me.

Mark

 

[bukfevr]

Re: 1992 100 hp oil injection

All right. Thanks for the help guys