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Merc 115 1990 Carburator amp oil problem

M

mariner_115

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"Hi all,

Right i have a 4 c

"Hi all,

Right i have a 4 cyl 115 (4Carb) Mercury that i overhaulled, The engine is good but i dont know what is happening to my Carbs. Okay the first time i started the new engine i had to use the normal outboard oil from our garage (mobil) and i mixed a little more oil than normal for the first run. Im not using the oil injection on my engine, im premixing. (oil injection removed) So the engine ran about 2 min with that mixture then it started running very rough.. u can hear that it isnt running on all 4 cyls. To me it sounds like its running on 1 cyl the top 1. Spark is fine on all 4 cyls. So when i press my key in ignition to choke(when engine is running rough) then it comes alive for a few seconds. Witch means that its a petrol problem.

Then i took all the Carbs off and cleaned them, When i started it was Fine!! Runing like a brand new engine. But Since then i have done 40 hours with NO problems using the Quiksilwer Outboard oil. Last weekend i went to the river on a sunday so i had to use the normal outboard (The same Mobil) as my first start. So it died on the river with me. Now its sounds just like the first time running on 1 cyl.. So i have to take the Carbs off again to clean.. Why is this happening??
Its clogging my carbs..

Can there be a problem with the cheaper oil?

Thanks for taking the time to read about my problem!"
 
"Is this mobil oil two stroke

"Is this mobil oil two stroke oil, if not then that could be your problem. Some oils just run better in outboard motors than others. Just like the old saying goes "cheaper aint always better"."
 
As long as the oil is TCW 3. T

As long as the oil is TCW 3. TCW = two cycle water cooled.
Compliments of IBNFISHN in an earlier post
 
"Thanks Lee & Noel for ur

"Thanks Lee & Noel for ur posts.

I know it's rather a strange problem that i have and maybe its sounds as if i dont know what im talkin about.. haha.. but.. there is a problem with this oil! Too me it looks like this oil doesnt burn as wel with the fuel. So when running my engine for long periods at low speed, it starts to run rough.And the oils starts to clogg?? (if its the right word) the engine.

I saw that that oil is now coming out of my prop! So i will not use that oil ever again, but now my engine is sick!!

Noel, the oil is TCW 3 but maybe it is a cheap oil?? Or there is somethin in that oil thats causing a prob for me..

Thank you guys!"
 
"Is this the Yamaha built 2&#4

"Is this the Yamaha built 2+2 Engine??? If it is one of these engines, it is meant to run on only the top two cylinders at speeds below 1800 rpm. If one of those two cylinders does not fire, the engine will barely run. The type of TCW3 oil you are using should not have the effect you describe."
 
"Hi Rob,

Yes i believe it i

"Hi Rob,

Yes i believe it is the 2+2 Yamaha built engine! And yes all spark is fine. The funny thing is that the engine has done 35 hours with NO problem.. (quicksiver oil). Then the very first tank that i used some cheap outboard oil. Now its sick! And now the oil is coming out of the prop.. this is the first time this has happened.."
 
"The bottom two carburetors do

"The bottom two carburetors do not have adjustable idle mixture screws. They have fixed idle passages which provide just enough fuel to lubricate the motor below 1800 RPM but do not provide enough fuel for the cylinder to fire. If, as a result of a stuck float, bad float valve etc., these cylinders do get fuel and start to fire, the motor will run very poorly. While the motor is idling or below 1800 RPM, you should be able to use a pair of plastic insulated pliers and remove the wires from the bottom two cylinders. The rpm should not change when the wires are removed. If it does,the carburetor is not working properly. If you do the same with the top 2 cylinders, the RPM's should drop drastically. Some cautions...Running the engine with the wires disconnected can do damage to the ignition system...ground the wire immediately after removing it from the spark plug...also realize that the voltage this motor puts out is enough to give you a pretty good shock so use caution. It also should be mentioned that the cylinders must get fuel at all times. If a carburetor is not providing fuel to a cylinder, that means it is also not getting lubrication and will quickly ruin the engine. As with any engine, a service manual is a must."
 
"Hi Bob,

Ive rebuilt all th

"Hi Bob,

Ive rebuilt all the carburetors.. And everything looked fine. but ill double check them. like u said maybe something is faulty in one of them..

Thanks
Jean"
 
"Bob,

So this is a Yamaha b

"Bob,

So this is a Yamaha built engine?? This is very interresting... Id like to read more about the history of this engine and what was the connection between Mercury and Yamaha??"
 
"Jean,
can give you a bi

"Jean,
can give you a bit on the Yami/Merc marriage that lasted until a few years ago.

Merc and Yami entered into a joint development partnership in 1972.

In 1974 Yamaha began producing the Mariner line for Mercury.

In 1983 the US Trade Commission put a stop to the open partnership between Yamaha and Merc, so to kinda skirt it, Yami continued to produce the Mariners for sale outside the US (primarily the Asian/European/Australian markets) and Merc started buying unfinished powerheads and gears from Yami.

When they introduced their entire new line in late 1985 (for the 1986 model year) you had a hybrid kinda engine. It was a Yamaha with a Merc ignition and castings (leg/empty lower unit etc).

This continued for many years on most of their models. In 2005, Merc discontinued US production of almost their entire (conventional) two stroke line (except the 50, 90 and 115 horse motors) which kinda ended things between them and Yami for good.

Now, according to Merc, the Opti's and Verado's are purely a US Merc produced motor (but I bet alot of the parts came from a carton with Chinese writing on it) and the smaller 4 stroke line is produced entirely by Tohatsu..."
 
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