25hp Johnson - gas going into oil tank, want to disconnect oil injection

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simplystressed

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Good morning.

Picked up a late 90's Johnson 25hp that appears to have gas going into the oil injection tank. From what I understand, something has failed on the fuel pump/diaphragm which is causing this.

Compression is 90psi on all 3 cylinders cold (don't want to run it until issue fixed), so think the motor is ok.

I want to disable the oil injection and go to premixing the gas/oil myself to avoid future worries.

How do you disconnect the oil injection on this motor? and do I need to get a new fuel pump since the existing one appears to be failing by letting gas into the oil tank?

Thanks
 
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hidef

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Re: 25hp Johnson - gas going into oil tank, want to disconnect oil injection

Your fuel pumps are fine there are two of them at the front of the engine behind the air silencer.

What has failed are the check valves in the oil mixer. This is a known problem with these engines and very easy to bypass and do away with. Disconnect the wires going to the oil sender and remove the oil tank and oil mixing chamber. Once you have removed the oil tank connect the fuel filter (The fuel filter is between the fuel pumps and the mixing chamber) to the fuel line that connects to the fuel rail on the port side. Your are connecting 56, 5 and 11 together if you look at the attached schematic.

Until you get it disconnected you can run 50:1 in your tank (which is what you will need to run after it is disconnected anyways).

Evinrude Fuel System Parts for 1996 35hp E35QLEDC Outboard Motor
 
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simplystressed

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Re: 25hp Johnson - gas going into oil tank, want to disconnect oil injection

hidef said:
Your fuel pumps are fine there are two of them at the front of the engine behind the air silencer.

What has failed are the check valves in the oil mixer. This is a known problem with these engines and very easy to bypass and do away with. Disconnect the wires going to the oil sender and remove the oil tank and oil mixing chamber. Once you have removed the oil tank connect the fuel filter (The fuel filter is between the fuel pumps and the mixing chamber) to the fuel line that connects to the fuel rail on the port side. Your are connecting 56, 5 and 11 together if you look at the attached schematic.

Until you get it disconnected you can run 50:1 in your tank (which is what you will need to run after it is disconnected anyways).

Evinrude Fuel System Parts for 1996 35hp E35QLEDC Outboard Motor
Click to expand...

hidef thanks for the quick and detailed response! I will get that fixed up. is around 90psi on all 3 cylinders when checking on a completely cold engine?

thanks again
 
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hidef

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Re: 25hp Johnson - gas going into oil tank, want to disconnect oil injection

I can't tell you about the compression when cold the book says as long as all three cylinders are the same when the engine is at normal operating temp it is good. I would say 90 across all three when cold is okay. based on your description you might have caught the failed check valve early enough so that the engine didn't get harmed. Make sure you also change out the water pump and inspect the thermostat. I highly recommend getting the OMC/BRP service manual for your engine.
 
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simplystressed

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Re: 25hp Johnson - gas going into oil tank, want to disconnect oil injection

Thanks for your help I removed the oil injection it was pretty straight forward. with the electrical connector disconnected now will that cause any issues/engine alarms?

thanks
 
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hidef

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Re: 25hp Johnson - gas going into oil tank, want to disconnect oil injection

No it won't.
 
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Rip & Tear

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hidef said:
Re: 25hp Johnson - gas going into oil tank, want to disconnect oil injection

Your fuel pumps are fine there are two of them at the front of the engine behind the air silencer.

What has failed are the check valves in the oil mixer. This is a known problem with these engines and very easy to bypass and do away with. Disconnect the wires going to the oil sender and remove the oil tank and oil mixing chamber. Once you have removed the oil tank connect the fuel filter (The fuel filter is between the fuel pumps and the mixing chamber) to the fuel line that connects to the fuel rail on the port side. Your are connecting 56, 5 and 11 together if you look at the attached schematic.

Until you get it disconnected you can run 50:1 in your tank (which is what you will need to run after it is disconnected anyways).

Evinrude Fuel System Parts for 1996 35hp E35QLEDC Outboard Motor
Click to expand...
I've got one of these motors that someone removed the oil system from it. They left open fittings on the port side of the motor that go into the case and intake manifold. Can you send pictures of what the plumbing is supposed to look like on that side?
 
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racerone

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Sounds like you are talking about small oil recirculation hoses.----They should have been left in place when oil tank / mixing unit was removed.----Sorry ----I do not do pictures and even the factory manual is vague on these.
 
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Crosbyman

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the small bottom to top nipple hose is used the suck out accumulated fuel/oil from the lower part of the crankcase and send it back up to the top bearing for oiling reasons. this concept goes way back 50+ years and today is still used on modern ETEC engines.
when the lower piston creates crankcase pressure the oily residues are pushed out and up to the top assisted by the upper cyl. vacuum on the upstroke. DO NOT REMOVE has stated !

see explanation on old 50's motors... nothing new under the sun :)
 

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Rip & Tear

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That's what I think they are, and I think they directly oil the crank bearings. Does anybody have pics of these lines and their routing. Thanks
 
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Crosbyman

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post model & year models differ you should get a proper service manual. modifying design intent is or may be a risky venture. why not fix the problem. ?
 
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jbcurt00

jbcurt00

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Rip & Tear said:
That's what I think they are, and I think they directly oil the crank bearings. Does anybody have pics of these lines and their routing. Thanks
Click to expand...
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