# 87 Evinrude 9.9 hesitates



## Truckmechanic (May 5, 2009)

I have a 87 Evinrude 9.9 tiller model that is giving me problems, I know it is small but maybe you can help me out. I will get the model and serial info as soon as I can and get it posted.
-When start up it runs good at idle. I go to throttle up and get about 1/2 throttle and and it begins to die. If I can catch it before it dies and open up the choke it will throttle up the rest of the way to WOT but still run kind of sluggish. I had done some research and all I could come up with was a jet in the carburetor was clogged so I disassembled and cleaned, put everything back together and runs exactly the same. Also if this helps it runs the same on muffs as it does in the water.


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## Defiant (May 5, 2009)

Have you checked the fuel pump to make sure it's pumping enough fuel? Did you remove the welsh plugs on the carb and clean under them? make sure the float is set level with the base when upside down.

Post the model and serial of the motor they had 2 different carbs that year .

Here is some good info on the 9.9/15 series of motors


https://www.sschapterpsa.com/ramblings/OMC/OMC%20info.htm


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## bassboy1 (May 5, 2009)

Defiant said:


> Have you checked the fuel pump to make sure it's pumping enough fuel? Did you remove the welsh plugs on the carb and clean under them? make sure the float is set level with the base when upside down.
> 
> Post the model and serial of the motor they had 2 different carbs that year .
> 
> ...


Those are my thoughts as well. The only two functions those motors have is fuel and spark, since they are nice and simple, and lack sophisticated computers, and all that garbage. Symptoms don't sound quite like a timing or spark issue, so I am led to believe it is gummed up/misadjusted carbs.


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## CarlF (May 5, 2009)

Clogged high speed jet is my first thought.
Could also be water in the carb, filter bowl & tank.
If it has a filter boat, take it off & pour into a cup to see if you have water in it.
If so, you need to flush the tank & lines & dry them to make sure all water is out.


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## Truckmechanic (May 6, 2009)

Wow...Thanks for all the help, I am going to do my best here so work with me  

I thought it could have been a clogged jet so I dismantled the carb and cleaned with cleaner and reassembled as my manual showed me how, When i put it back together the same thing. Could I have not cleaned it well enough? I let evreything soak in cleaner.

Fuel was brand new from the station, I have never had problems with fuel there.

I am not sure what a welsh plug is.

How can I tell if it is pumping enough fuel?

I will post the model number as soon as the sun comes up and I can get it posted.


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## CarlF (May 6, 2009)

How old is the tank? Just because it has a fresh tank of gas does not mean you dont have a water problem. A tank can gradually build up water until it finally becomes a problem. Or one rain storm with the vent loose & you have a problem. Heck, could even get bad gas from the service station. Dont count the water problem out yet!!!


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## Captain Ahab (May 6, 2009)

It sounds like a fuel problem of some sort - Although if it was bad gas or water it woudl remain consistent. If I were to guess i woudl say you are loosing vacuum in the fuel line or carb. Does the fuel primer bulb (the thing you squeeze in the gas line) remain hard? Try pumping it as you are running the engine and see if it solves your problem. if so, you either have a bad connection on the fuel line or a small crack in the line.


The reason it only hesitates above 1/2 throttle (and not through the entire range) is becuase it is just not getting enough gas.

Also, merely soaking the jet might not be enough, take it off and visually inspect it with a flashlight - is the aperture hole completely clear and round? if not, take a needle and clean out whatever is blocking the hole.


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## Defiant (May 6, 2009)

Also your fuel pump Diaphram could have a pin hole in it and not pumping enough gas at WOT try pumping the bulb like Captain Ahab said and see if it helps ..The welsh plugs are the little round plug looking things on the carb there should be new ones in the carb kit. 


What is the model number of that motor.


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## Loggerhead Mike (May 6, 2009)

> Also your fuel pump Diaphram could have a pin hole in it and not pumping enough gas at WOT



my motor likes to do the same thing. it seems to blow the diaphram every other time out, and the "new" ones we order have probably been sitting on a shelf for 20 years. still trying to figure out why they keep blowing


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## Tunnels (May 6, 2009)

I had a similar problem with my 9.9 Johnson. As Ahab said, it could be a primer bulb. That was my problem. I was lucky enough (after carb work) to know someone who also had a Johnson. I hooked up his tank & lines & it ran good. Just a matter of checking hose clamps, etc. to narrow it down.


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## Truckmechanic (May 7, 2009)

My line and ball is practically brand new. I know it could still be bad but it only had a couple uses then the motor sat for about a month I didn't get to fish then this happened. I store everything inside so I don't think that I have water in my fuel. I am going to try to get it out today if it will quit raining and see if pumping the ball will help it any. I also got the numbers for everyone.

Model# E10RLCDB



This motor was originialy a long shaft and I had it reduced to a short shaft.


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## rcgreat (May 7, 2009)

I was having similiar problems with my outboard and come to find out I got a tank full of bad gas (particles in the fuel) and it plugged the line going to the fuel pump enough that the motor would not stay running over an idle. Thank god for the screen in the fuel pump or I would have had a real mess on my hands. I took a sample of fuel in a jar and thats how I found the tainted fuel. I then drained and filtered the gas, cleaned out the fuel lines and blew out the filter in the fuel pump and have had no issues since. I now run an inline fuel filter.


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## KMixson (May 7, 2009)

I have an 1975 Evinrude 9.9 that runs great. But, one time I purchased some gas at a station on the way to the boat ramp and it turned out to be bad gas. It gave me a fit. It ran well the night before and then would not run at the ramp to save my life. I took it home and as I was tinkering with it I decided to hook up another tank to it just to check the fuel. I hooked up my other tank with some older fuel and it ran fine. Just because you purchased the fuel recently does not mean it is good.


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## Truckmechanic (May 17, 2009)

Well, I rebuilt the fuel pump, Carburator, replaced seals in the gearcase and repalced the water pump. I runs better now that it ever has. Thanks everyone for your help.


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## rcgreat (May 17, 2009)

congrats, its gratifying when it all works out in the end =D>


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## Truckmechanic (Jan 19, 2010)

I know it is an old thread but I never got the chance to thank everyone for their help, thanks a bunch guys you helped me get it running like a new one again. I ended up rebuilding the fuel pump and carb. So it is running great now


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## dougdad (Jan 25, 2010)

First check all hose fittings for a good tight fit and no leaks. Suction leaks here will cause that problem. Also some of those older motors have a set of reed valves behind the carb. If they get to dirty, corroded, or crack, this will cause that problem too. These are just thin plates of usually stainless steel that seat and un seat according to the stroke (intake or exhaust) the motor is on. I have seen a chunk of carbon get stuck in these and cause this same problem.


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