1987 Mercury 90HP - No Oil Flow from Fuel Pump to Crankcase

[polarkraft165]

Pretty much says it all. was working and running great and had a hose work loose. Didn't run it that way so i'm thinking im ok. replaced all the tubing with new and fill tank. Premixed fuel in the tank to 50:1 just to be safe.

When running, it drew the oil from the tank to the oil pump, bled the screw on top and oil came out. Oil is present from the oil pump to the fuel pump but that is where it stops.

Again, while running there is only a hint of oily coating on the clear tube running to the crankcase. What is this hose to the crankcase for? Should it be full of pure oil? or mix or what. Pretty sure it's not supposed to be empty. I can see air moving an oiling film through it?

Do i have a fuel pump not pumping oil to the crankcase?

 

[racerone]

The oil pump puts oil into the gasoline before the mixed fuel goes to the carburetors.-----The oil pump is driven by a plastic gear.----I have seen those gears stripped.------Have your friendly and trusted repair shop check this out.---Have them do a pump output test.------And have them explain how the system works as well.

 

[polarkraft165]

So, help me understand what the line running to the crank case does? If we're mixing fuel and the pump is drawing it and the engine is running fine, i just would like to understand what the line is supposed to deliver to the crankcase.

 

[racerone]

Lets start at the beginning.----Do you understand that there is an oil pump and a fuel pump, yes or no?-----The fuel pump is driven by + pressure pulses from the crankcase.---The oil pump is gear driven------I can not see your motor to see this clear line.----It may have been installed by a previous owner.----Post pictures or run to your friendly / trusted repair shop to have this all explained to you

 

[Texasmark]

Get a manual and they will explain the operation and tell you how to bleed the system. Either iboats has them or ebay.

 

[Faztbullet]

Sounds like a recirc line OP is talking about...

 

[polarkraft165]

I've attached a couple of pictures to show the clear tubing that was all replaced by me after one had become brittle and started to leak. Racerone, did you read my description in the original post where i stated this already...yes or no?

Yes, i also understand that there is a gear driven oil pump and a fuel pump...as shown in my photos. Did you read where i stated in my original post it pulled oil from the on board tank and i bled it using the bleed screw on top of the oil pump....yes or no?

Possibly, just maybe, the pictures will elicit some useful information this time around.

 

[racerone]

You funny-----The clear hose in the second picture is a PULSE HOSE as is the hose in the first picture.-----They put crankcase pressure on the diaphragm in these pumps.-----The fuel pumps on these run off crankcase pressure pulses.---There may be some fuel vapour in these hose .------If you would need any parts for you motor I think I have abiout 6 off them for parts.-----Some folks do not understand the hoses on these motors.----I am very familiar on how this system works.----Sometimes it is hard for a novice to understand how simple these outboards are.-----Maybe , just maybe this helps you.----And yes I am blunt with my postings.-----I try to steer folks in the right direction.

 

[polarkraft165]

Not trying to funny. And, yes you are a bit coarse. However, your answer was very helpful. . That;s what i needed to understand. just wanted to make sure that line was to provide positive crankcase pressure to the fuel pump.

I've marked my oil level in the oil tank and have premixed to 50:1 in the fuel tank....I'll run it and monitor the oil level to ensure the pump is pumping as it should.

Thanks again for the help

 

[racerone]

Your lawyer and doctor are likely very polite.------But they charge you $500 / hr.---No pictures of your motor till post # 7-----So far this has cost you nothing to learn some facts !!!----Post # 1 says you had ---" no idea what that hose was for " and now you know.

 

[polarkraft165]

you sir are a knowledgeable arsehole.

 

[Faztbullet]

You need to replace the clear line on pulse with a nylon reinforced hose and lose all the worm clamps, use the fuel line wire ties.