Oil injection pump failure?

[dterwill]

My 75 hp Mercury 1993 model #1075412ND 3-cyl has recently been skipping at idle/running on 2 cyl intermittently. It clears up with running at higher speeds but takes a while to get running on 3-cyl. Running new plugs also fixes it for about 10 hrs of run time. Carbs are adjusted, starts well, has for past 3 years run exceptionally well. I just noticed it is using far more oil than it used to. I suspect the oil pump may be faulty and fouling the plugs. Can anyone offer insight to this problem?

 

[rickdb1boat]

Re: Oil injection pump failure?

Disconnect it and do away with it and mix your own! That way you know it's right!!

 

[Neikensnest]

Re: Oil injection pump failure?

I took the stupid pump out. (I mix my own fuel when I fill up 1 pint to six gals. I have no problems now. You also don't have to worry about being out and running out of oil! Always pump the gas first so you don't put oil in then not enough gas. I broke it down to the 1/2 gal. Each time I put in 6 gallons I dump in the oil. If it won't take six I top it of and go to the chart for the proper amount.

 

[ODDD1]

Re: Oil injection pump failure?

Dterwill, keep the oil injection. It is a safe, reliable, convenient system....an excess of oil usually means the oil check valve between the fuel and oil is weak, allowing excess oil to bleed into the fuel....your missing problem may be something else entirely [spark check?] you guys that knock oil injection systems, why do you think they are on motors???? Maybe the manufacters thought they could sell more motors?? Maybe the people who are BUYING engines wanted it?? Start adding all the motors that have toasted because somebody 'forgot' to mix oil/ mixed incorrectly and oil injection dont look so unreliable.....

 

[dterwill]

Re: Oil injection pump failure?

ODDD1- I must say I am leaning towards the idea of the spark. I have read more posts that are similar in problem and end up being attributed to electrical system. My most recent check of the oil resevoir indicates it where it should be after motoring for 2 hrs. I am thinking I need to look at the coils and wires. Playing with the carbs seems not to affect the eventual skipping once I resume low speed or idle for any length of time. Sometimes it has the feeling it surges as it begins to run on all 3 cyl. Frankly the plugs all look OK but replacing them seems to rectify the problewm for a while.

 

[ob]

Re: Oil injection pump failure?

If one of the advantages to oil injection is the fact that you won't forget to add oil count me out as a passenger aboard your vessel.Seems clear that plugs are fouling as a result of rich oil mix .perhaps the check valve is leaking through as mentioned above.Reliable???Oil injection systems were an EPA driven implimentation to cut down on oil emissions through two stroke exhaust systems.Great idea ,and as soon as it is perfected and not subject to constant attention it will be a convenient fixture.If checking oil level in reservoir ,inspecting hoses for leaks,priming system ,and monitoring levels seems more trouble free than mixing 50:1 then injection system might be for you.Heck the manufacturers trust their own systems so much that they recommend mixing at 50:1 on new units until oil usage through these "reliable" systems can be verified.In short , On your particular application I would recommend going with first two suggestions and scrap the injection system. Many Merc wrenches will tell you the same thing.

 

[rickdb1boat]

Re: Oil injection pump failure?

Amen OB, I like seeing that oil going into the Gas! 15 Years and have not forgot it yet! Nor have "I" broke down doing it!!

 

[chuckybaby]

Re: Oil injection pump failure?

My money says it's an ignition problem. Weak coils and/or bad wires. The VRO on my OMC 200<br /> crapped $571.27 ago. I was running about 7:1 mix...looked like a blue tracer bullet coming<br />down the lake. Plugs looked like they were dipped in tar...never missed a beat (except that the primer lever had to be in the prime position to run)<br /> <br />Besides, had a snow blower that did the same thing. Slap in a new plug and it would run for a couple of hours then lose power and eventually die. Did that till the parts guys suggested a new coil. Machine runs like new now.

 

[dterwill]

Re: Oil injection pump failure?

Thanks everyone for the advice. I will get the oil injection checked to be sure but will also replace wires and coils, it is 9 years old and been in salt the whole time. I believe it is electrical because I can isolate it to one cylinder but have not yet switched out the coils. Compression was checked this spring and was good in all 3 cyl. I will repost when I get the solution.