Yamaha Surging Power/Idle Problems

[cookiedoh]

I have a 1987 115hp ETX outboard. The previous owner had not used it in the last two years. I cleaned the carburetor bowls and jets (weren't very dirty), I put new plugs in and I hooked up some fresh gas. However, It won't idle without taping the choke on/off. It even has a hard time running at slow speeds if I don't click the choke on when it starts to stall. In gear with some throttle (or with fast idle) the motor surges and gives more power for a second and then returns producing an "uneven" running sound. Full throttle does not feel like full throttle speed. After I gave up and brought it home, I noticed that there was oil dripping out of the carbs. My oil control unit is broken too by the way, I doubt it's related but thought I would mention it. I do have oil in the main tank on the motor, and it does appear to be using the oil.<br /><br />So, can't idle, surging power, oil dripping from carbs. Do those symptoms point to one problem?<br /><br />Thanks.

 

[Ray Neudecker]

Re: Yamaha Surging Power/Idle Problems

Yes, fuel restriction. the carbs need to be completly torn down and gone through as well as replacing the fuel pump. Install a water seperating filter in line and do away with the gas disconnect and engine mounted filter.

 

[cookiedoh]

Re: Yamaha Surging Power/Idle Problems

For some reason, the online yamaha part system doesn't show the part I need for that year. I tried going forward in years to see if the diagram showed the part. In the early 90's I found it. They call it a "JET,SLOW AIR BLEED" Do you think it's the same size for my 87 motor (60)? They are like $10 a piece, anybody know of a cheaper source? I've seen some Mikuni Jets that look similar for $2-$3 but I don't really know if it's the same thing I need. Local dealer did the same thing, looked up an 87 115etxh and it doesn't show the part I need.

 

[Ray Neudecker]

Re: Yamaha Surging Power/Idle Problems

That would be the proper jet number for the low speed air jet, The phyiscal size may not be correct for your carb since they changed in some models in the early 90's. I do have them and the main nozzles for those carbs in used parts. Email me at neudecray@hotmail.com with the part number stamped on the carb and a shipping address for a price.

 

[cookiedoh]

Re: Yamaha Surging Power/Idle Problems

Everything is back together and it runs great. Thanks for your help! I do have a couple more questions...

I set the float height according to specs Seloc my Seloc manual for my motor. I had to bend all the tangs on the floats down quite a bit. It made an angle 90 then 90 degrees, like a crooked V instead of an L shape. Does this seem normal?

Questions 2, why is there a shround on the plastic shround that protects carbs front of the carbs? It's not like it needs Im be airtight, right? I'm just wondering if I need to replace dont gasket, but I don't think it's that critical to operation.

 

[cookiedoh]

Re: Yamaha Surging Power/Idle Problems

Spell check seems to have messed up that post. Ignore that one.

I set the float height according to the specs in my Seloc manual for my motor. I had to bend all the tangs on the floats down quite a bit. It made an angle less then 90 degrees, like a crooked V instead of an L shape. Does this seem normal?

Questions 2, why is there a gasket on the plastic shroud that protects the front of the carbs? It's not like it needs to be airtight, right? I'm just wondering if I need to replace that gasket, but I don't think it's that critical to operation.

 

[Ray Neudecker]

Re: Yamaha Surging Power/Idle Problems

(1) Hard to say from your description, but if the float works freely and is at the called for level, it should be correct. (2) Basically the air box cover is a silencer and the gasket is really unnecessary.