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Mate
Posts: 1
Registered: ‎10-17-2019

1998 70hp oil injection

bought a boat and motor from a friend. I had been on fishing trips with this boat before I bought it and it ran fine. the motor and boat have very few hours. the previous owner had the motor gone over completely a few years prior. after I bought it and took it out the NO OIL warning came on. I added oil to the gas tank as a precaution and took the boat home. I purchased a shop manual and read up on this problem. the oil tank and pick up are fine and clean. I contiued to use the oil injection and oil in the gas tank till I could solve the problem. I finally disconnected the oil injection system as per instructions. the cost of a new oil/fuel pump is almost $450 plus labor. no shop around me wanted to work on the motor and if they did,it would be at $125 an hour!. when I diconnected the oil injection hose to the motor it was full of oil so maybe the injector was working and the NO OIL warning signal was defective. I have been using the motor and it runs fine at higher speeds but sometimes loads up at low speed and doesn't want to take gas right away. original plugs were wet with oil when I first had the oil problem and was adding oil to the tank, thats why I think the pump was still working. I may have added too much oil to the tank. I have been replacing it with the  right mixture. going to put new plugs in, old ones looke glazed. will change fuel filter also. carbs look nice and clean and I drained them.

Admiral
Posts: 8,401
Registered: ‎07-14-2011

Re: 1998 70hp oil injection

Excessive oil in the fuel line between the OMS pump (often called VRO) and the carburetors is often caused by a weak or leaking oil outlet check valve which can allow the oil to migrate into the fuel pump chamber of the pump body, richening the mixture.

 

If the check valve is weak, the pressure buildup inside the remote oil tank from temperature changes can overwhelm the valve and allow oil to seep into the fuel pump chamber.  The oil tank is vented for vacuum as the oil is consumed, but it is designed to hold pressure to avoid oil in the boat if overfilled and the oil expands from temperature increases during the hot summer days.

 

 

 


"There is never just one thing wrong with a boat";
                    -- Travis McGee, main character in a book series by John D. McDonald 


 



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The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.

The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.