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40 ELPTO Oil Pump

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Bailey Henry

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"I have a '96 Mariner, inl

"I have a '96 Mariner, inline four with constant ratio oil pump. When it sits for more than a couple of weeks oil gravity feeds thru the pump into fuel line and eventualy the tank if the fuel line is left attached. I expect this is a common problem, a real pain to start and clear out after it sits a few weeks. I think I would like to disable the oil pump and go to premix, but I'm open to sugestions if there is a fix for this. If I disable the pump do I need to remove the drive gear and shaft? Or is it enough to just close the inlet and outlet lines?

Thanks,
Banjo"
 
"Bailey, that particular syste

"Bailey, that particular system is easily removed since it is simply spliced into the fuel line with a T connector.

Additionally, being a constant ratio pump it provides no additional benefit over mixing gas/oil yourself (as does vro's).

The oil pump is driven by a gear extending into the powerhead, but if you simply disconnected all the lines/hoses, you could leave it in place (attached) without any ill effects. I don't believe you really even have to plug the line holes, the pump would simply sit there and run all by itself basically doing nothing.

Just replace the T-connector in the fuel line with a straight connector."
 
"Graham,

Thanks for the qui

"Graham,

Thanks for the quick reply,

Bailey"
 
The pump is normally submerged

The pump is normally submerged in oil...I'm not sure if any problems might result from dis-connecting the hoses...especially if the connections are left open...perhaps a short length of tubing filled with oil and connected from the pump inlet to the outlet might allow the pump to simply recirculate the oil in the tubing and prevent it from seizing.
 
"Scott, I thought about the ch

"Scott, I thought about the check valve, but, the factory manual says it's to keep gas from flowing back into the oil. Does it work both ways? If so I'd probably replace it and keep the oil pump working. Bob, I'm also concerned about the pump running dry and considered the tubing loop with oil recirculating. I may be overthinking this, it seems simple enough to take the pump off and remove the drive gear and shaft.

If everybody thinks replacing the check valve will take care of the problem, I will try that first.

Thanks for the help,
Bailey"
 
"Bailey, I have a 95 Merc/Yama

"Bailey, I have a 95 Merc/Yamaha 115 HP 2+2.....I think it is the same engine and oiling system...I have the same concerns about removing the oil pump...There is no warning buzzer for pump pressure(only low oil level) and that is a concern. The oil tank also leaks externally when the motor is tilted forward in spite of a new cork gasket recently installed. I am either going to replace the tank and all the hoses or convert to premix. Last year I posted a similar question and someone mentioned that crankcase volume might change if the pump is removed...don't know if that is correct. You would also have to fabricate some sort of block-off plate to cover the area where the plate was removed...I have the service manual but it doesn't give a clear picture of the oil pump internals. If someone has this same motor and has changed over to premix, I would appreciate hearing about their experience. Last year the summer ended before I could make any changes...This year I would like to take care of things before a problem develops."
 
"Bailey, alternately what you

"Bailey, alternately what you could do is obtain a small shut off valve - what I'm thinking of is the little hydraulic valves or gas valves (if you are old enough to remember the old shut off valves on lawnmowers) available from most auto parts places and splice it into the oil line between the tank to the pump.

Then when you are not using the motor for more than a day or two, simply turn the valve off keeping the oil in the tank.

The only potential drawback to this, is, if you ever forgot to open it up again before use, the result could be catostrophic...."
 
"Graham, Old enough to rememb

"Graham, Old enough to remember shut off valves on lawnmowers? When I was a kid we swept the yard in the country where I came from. I thought about the shut off idea, I think in the fuel line just beyond the T connector would be much safer. If you shut off the fuel line here and disconnected the line to the tank the oil line would have no vent and couldn't flow. If my thinking is sound that may be the best bet yet.

Thanks,
Bailey"
 
"That actually sounds like a b

"That actually sounds like a better idea - then no worries about forgetting about the oil, worst that could happen is you drain the battery trying to start before you remember to turn on the gas line
"
 
"if you want to take it off, g

"if you want to take it off, go ahead. don't worry about the loop thing. remove the shaft and the pump will not do anything. parts are available to remove it and plug the hole, and a cover too. you don't really need it, but it's there. no volume problem either. personally, I'd try the check valve. if it doesn't work, it cost you under ten bucks."
 
"Thanks for all the help, I&#3

"Thanks for all the help, I'm going to see if I can find a check valve tomorrow and try that. If that doesn't do the job I'll pull the pump and remove the shaft and gear.

I'll let you know how it works out,
Bailey"
 
"I spoke with a lifelong Mercu

"I spoke with a lifelong Mercury mechanic/dealer yesterday, he says the check valve is in fact one way, stops the gas from diluting the oil. He said they never replace them and didn't have them in stock. He checked mine and said it didn't feel right, ordered one, twelve dollars. Tried to get the pump off to remove the shaft and couldn't get to the bottom bolt. It's a hex head and the allen wrench is to short on one end, won't clear the pump, and the long end won't clear the bottom motor pan. I'll install the check valve when it comes in and see how it works.

The mechanic says this is a common problem with this motor. Although the motor and pump system are fairly bullet proof gravity fed oil fills up the fuel line as the gas in the carbs evaroprates. This is made worse because I only use the boat in the spring and early summer. I still think I would be better off running premix and running the carbs out of gas after each use, it's always worked in the past.

Thanks for all the help,
Bailey"
 
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