Non conventional issues.

DeepCMark58A

Commander
Joined
Aug 17, 2015
Messages
2,539
So was having a sudden issue with my Mariner 115. I have only owned the used motor for a year. At first I suspected a fuel issue with the built in fuel cell so I installed a clean 6 gallon cell, no improvement. I replaced the plugs and wires, no improvement. I changed out the fuel filter no improvements. Took the shroud off to get a look at the carbs, they are spotless. I am feeling dejected because I am getting past the level I am comfortable with. I decide to clean the inner shroud and put the intake box back together. Found a crack in the plastic intake shroud right by the # 4 cylinder. Not sure how a part that does not see torque cracks like that but it is a 1993 motor, things break. Part ordered, jb weld will get us thru the weekend.
 

airshot

Vice Admiral
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Jul 22, 2008
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5,403
Appearance from the outside if a carb means very little...so you need to see the inside, if you can drop the carb bowl see how much crud is inside. Typically this is where the issue is. Once an engine gets to be around ten yrs of age, crud in the fuel system can start to show. Best thing you can get is a " factory" service manual, no aftermarket Clymers or others, only factory !! All the proper setup/ link and sync information will be in that manual. Good luck....
 

crazy charlie

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Joined
May 22, 2003
Messages
5,581
So was having a sudden issue with my Mariner 115. I have only owned the used motor for a year. At first I suspected a fuel issue with the built in fuel cell so I installed a clean 6 gallon cell, no improvement. I replaced the plugs and wires, no improvement. I changed out the fuel filter no improvements. Took the shroud off to get a look at the carbs, they are spotless. I am feeling dejected because I am getting past the level I am comfortable with. I decide to clean the inner shroud and put the intake box back together. Found a crack in the plastic intake shroud right by the # 4 cylinder. Not sure how a part that does not see torque cracks like that but it is a 1993 motor, things break. Part ordered, jb weld will get us thru the weekend.
WHAT is the issue you are experiencing???????
 

DeepCMark58A

Commander
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Aug 17, 2015
Messages
2,539
The issue appeared to be either fuel or spark, it was neither, there was a crack in the intake right up the lower carb. JB weld should hold till the new part arrives.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,105
When you say crack in the intake do you mean a crack in the crankcase cover? It seems unlikely, as crankcases and covers are a single casting and sawed to separate. So what exactly cracked?
 

DeepCMark58A

Commander
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Aug 17, 2015
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2,539
When you say crack in the intake do you mean a crack in the crankcase cover? It seems unlikely, as crankcases and covers are a single casting and sawed to separate. So what exactly cracked

You know anything about this motor? There is an aluminum plate that covers the carbs, it has intake holes in in and there is a plastic cover that goes over the front. There was an open crack that went directly into the lowest number 4 cylinder carb. That was the problem.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,105
Gee, testy aren't we.

So, you have a crack in your airbox, and you are blaming that for poor running? Good luck with that fix.
 

KJM

Lieutenant
Joined
Jul 31, 2016
Messages
1,271
What are the symptoms you are experiencing with the motor? Will it run, does it keep cutting out, sputtering at high rpms? Just saying you have an issue doesn't tell anybody enough to hazard a guess as to the problem. Pictures of that crack you mention would also be very helpful.
 

brodmann

Chief Petty Officer
Joined
Jun 17, 2008
Messages
426
A crack in the airbox is not your problem. When making carburetor adjustments and fine tuning things, it's usually done with that taken off. I'm guessing the jets are clogged inside the carburetor, but with no real description of symptoms, we're not able to diagnose very well. Crack in airbox is not going to cause you to have a performance issue. It is there to keep birds from flying into the motor!!
 

DeepCMark58A

Commander
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Aug 17, 2015
Messages
2,539
A crack in the airbox is not your problem. When making carburetor adjustments and fine tuning things, it's usually done with that taken off. I'm guessing the jets are clogged inside the carburetor, but with no real description of symptoms, we're not able to diagnose very well. Crack in airbox is not going to cause you to have a performance issue. It is there to keep birds from flying into the motor!!

I replaced the airbox and the acceleration and top end speed returned. I must have knocked something lose when I replaced the airbox.
 

mahadav112a

Recruit
Joined
Aug 2, 2023
Messages
2
I replaced the plugs and wires, no improvement. I changed out the fuel filter no improvements. Took the shroud off to get a look at the carbs, they are spotless. I am feeling dejected because I am getting past the level I am comfortable with. I decide to clean the inner shroud and put the intake box back together. Found a crack in the plastic intake shroud right by the # 4 cylinder. Not sure how a part that does not see torque cracks like that but it is a 1993 motor, things break. Part ordered, jb weld will get us thru the weekend.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,105
Gee, I don't believe it. My '93 Merc 135V6 has lost it's plugs for the airbox. I duct taped to seal it, however, I cannot believe it make any difference. I expect it keeps the water out of the carbs. if it got there somehow. However, the cowling does that real well. I think you are chasing wild geese...JMO
 

DeepCMark58A

Commander
Joined
Aug 17, 2015
Messages
2,539
Gee, I don't believe it. My '93 Merc 135V6 has lost it's plugs for the airbox. I duct taped to seal it, however, I cannot believe it make any difference. I expect it keeps the water out of the carbs. if it got there somehow. However, the cowling does that real well. I think you are chasing wild geese...JMO

I installed the replacement and ran the motor from hole shot to full throttle several times and the power is back to what it was. The goose is back in the pen.
 
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