View Full Version : Mercury oil injection Problem

04-04-2007, 10:32 PM
I recently purchased a 98 200 v6 Mercury EFI...after about 5 hrs use the oil inj alarm came on very faintly....the main oil tank had slightly sucked itself in and the little oil tank on the motor was slightly low so of course the float sent the alarm off....i found that one of the pipes ...i think it was the return pipe to the main tank was blocked.....so i pulled all oil pipes ...incl both tanks off and cleaned everything out as new....filled with new oil and everything seemed fine....done approx 2 hrs and it has started to do it again....any ideas....

Cheers Mick:o:o:o:o:o

04-04-2007, 10:51 PM
Check the breathers on the oil bottles.

04-04-2007, 10:53 PM
It has got no breathers on the bottles.....main filler has sticker saying
Keep caps airtight to prevent engine failure ????

04-04-2007, 11:10 PM


Have a look at these might point you in the right direction

05-04-2007, 12:01 AM
Mercury oil injection is known to fail.
disconnect it before you have an engine blow up.
i bought a brand new 200HP Mercury in 2000 and disconnected the oil injection before it fired its first shot.
better to premix fuel and oil and know the engine is definetly getting lubricated.
i think the Mercury V6 oil injection is a pressurized system, so the main oil bottle won't have a breather.

05-04-2007, 12:31 AM
I was thinking about dis connecting it and running pre mix...but some mates say yes you can do it and others say defiantly not....anyone got any advice .....i thought these motors ran leaner at idle and richer at fuller revs....????....that would be one downfall of pre mixing the oil....bloody smoky 2 strokes....

05-04-2007, 01:36 AM
I removed the oil injection on a 200 black max that I had on the back of a 5.65 metre half cabin.

If you do do it you need to removed the oil pump drive shaft and you need to blank off all of the oil lines properly.

I ran it on 50 to 1 premix with good quality oil and even then I had trouble with it oiling up at low revs. It was fine once you opened up the throttle and got up on the plane but it used to cough and splutter a bit if you were travelling slow along a river or a long harbour entrance etc.

Boat up on plane and away it would go, drop off the plane and within a couple of minutes it would run rough. Slip it out of gear and give it a rev and it would clear only to happen again within a couple of hundred metres.

I wished I had just fixed the initial problem rather than revert back to premix on that engine.

- Darren

05-04-2007, 07:42 AM
Yes my old halfcab had a merc with oil pump removed and at idle with canopy up I could blow smoke rings.

05-04-2007, 07:52 AM
Hi Snelly
Guy by the name of Paul Ravenscoft is the man you want to talk to, local merc guy, works over all the state and you may have even come across him in ya travells or his travells as he does a bit of service work down there.
his number is 0409840687
just doing some prep work on the boat for a weekend at the hummocks, filter, have a look at why my fuel flow meters not working right, new 300m anchor ect

05-04-2007, 08:37 AM
Cheers thanks Blaze...

05-04-2007, 01:39 PM
I have a 2002 merc efi 150 and have been caught out a couple of times with the same problem. The only way i could fix it was to undo the tiny filler cap on the engine oil bottle and run the engine untill the air was removed from the system.

good luck


05-04-2007, 04:02 PM
Does anyone know of a web site thats shows the complete engine manuals or diagrams...worked out that the hoses were on wrong but i am unable to find one outlet..????

05-04-2007, 10:46 PM
Oil injection pumps does require servicing, few service centres seem to actually put the service kit in during the schedule service. Most motors that have oil injection fail are the ones that do not have regular use. if you use your motor less than every two months remove your two stroke oil from reseivor and replace before use after shaking well before running motor. the oil does seperate during storage. Stored petrol in your tank is also a cause of failure as the octance drops after a few weeks and petrol constistancy changes with age. If you are using the oil injection system do not add oil to the petrol in your tank as the varible injection is a basic mixing system and can not calibrate for the change in petrol constistancy and then runs lean on oil leading to engine failure. ratio at idial is 50 to 1 and at max. revs 100 to 1. Preminium unlead can cause problems in efi models as the alcohol content can cause incorrect data to the computer programming as quick silver recommends the use of standard unleaded petrol only in their motors

05-04-2007, 10:57 PM
There are two hoses of the main oil tank...one goes to the lower crankcase tail...and the other to the tee piece one way valve...but there should be another hoses.???...

05-04-2007, 11:14 PM
150/175/200 (EFI)
OIL INJECTION COMPONENTS have a look at the second link Iput in.

05-04-2007, 11:30 PM
i'm pretty sure the reservoir under the cowl is kept full with the oil from the big reservoir in the boat.
it does this through the hose from the bottom of the crank case.
it relies on crankcase pressure.
i have seen a shit load of V6 Merc's hand grenade due to oil injection failure.
that is why i don't have it connected on any of my motors.

06-04-2007, 12:04 AM
I did and it does not show where the pipes go..

07-04-2007, 11:52 AM
Does anyone have one similar to mine who can lift there cowl and tell me what pipes should run where...there are two running from the main oil tank ...one black and one black and blue...please anyone ????

07-04-2007, 12:26 PM
The Black Hose Should Go To The Crankcase ,the Blue Stripe Line To The T Piece Connected To The Oil Resovoir.check They Are On The Right Way On The Oil Tank In The Boat,blue Stripe To The Pickup.the Middle One ,black One To The Side.run The Engine With The Cap Of The Resovoir On The Motor It Should Fill Up Straight Away.if Not Un Screw The Fitting In The Crankcase It Is Ment To Be A One Way Valve,make Sure Its Blowing Out Not Letting Air Back.if Thats Ok I Have Sometimes Seen The Hoses Split Where They Go Through The Cowl,undo The 2 Screws ,seperate The Adapter And Check The Hoses.its A Pretty Simple System.most Of The Failures Are When The Oil Pump Drive On The Crank Strips,its Only Plastic.if That Happens Then Disconect The Oil Injection System.they Run Fine Either Way.
Hope This Helps

07-04-2007, 06:13 PM
Thanks opti....on the t piece there are two tails once facing down and the other parallel to that ...which one does the blue /black go on and what is the other tail for?? Cheers Mick

07-04-2007, 06:50 PM
The Blue Stripe Hose Goes On The Middle Fitting ,the One Facing The Front Of The Motor,the Top Fitting Goes To The Oil Resovior.the Bottom Goes No Where.its A Pressure Relief Outlet,incase A Hose Gets Blocked Or Something Like That.

07-04-2007, 08:22 PM
Thanks opti for all your help.....the marine place i purchased the motor from was telling me there should be another hose for the bottom tail on the tee piece..no wonder i couldnt find it....once again thanks for your help..