# Mercury 9.8 problem



## exide9922

Another motor question, on my other motor. Got this mercury 9.8 with the boat I bought. Tested it in a large bucket in my garage, seemed fine. Took it out on the lake yesterday and it went a few hundred yards and shut off. Got it started a few more times and it did the same thing. Had trouble starting it back up after it would shut off. Could it need a new spark plug? Fuel filter? I don't know much about motors. Any help would be appreciated


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## Seaturd

Sounds to me like the check valve in the bulb on the gas line is no good. Will it keep running if you keep pumping the bulb?


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## bdawg

I had that trouble with my Mercury 9.8hp. There were cracks in the gas line from the tank to the motor that was causing the line to lose pressure. The cracks had electrical tape around them but that didn't work. Motor ran fine in cold weather when the line was stiffer. Took me a year to figure it out and replace the line. I thought the carborator was clogged. 

Also, do you have the little screw on the cap of the gas tank unscrewed when you are using it? I think it needs to be unscrewed for the proper function of the tank/line. I may be wrong on this though. I am no expert. These are just my experiences with my little motor.


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## exide9922

bdawg said:


> I had that trouble with my Mercury 9.8hp. There were cracks in the gas line from the tank to the motor that was causing the line to lose pressure. The cracks had electrical tape around them but that didn't work. Motor ran fine in cold weather when the line was stiffer. Took me a year to figure it out and replace the line. I thought the carborator was clogged.
> 
> Also, do you have the little screw on the cap of the gas tank unscrewed when you are using it? I think it needs to be unscrewed for the proper function of the tank/line. I may be wrong on this though. I am no expert. These are just my experiences with my little motor.


Actually I didnt know about the vent on the gas tank, it was shut. I figured that out last night. opening that helped it to start, but it's not spitting out water. I believe i have the motor in a deep enough bucket... Someone mentioned the impeller might need replaced? I guess i need this motor to start spitting out water first. I found the hole where the water is supposed to come out, but where does it take it in?


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## Popspastime

Takes it in on both sides of the lower unit.


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## bdawg

My Mercury had a steady stream of water coming out. (when it was working) It also died after a couple hundred yards due to overheating. It will restart, but I don't dare to run it long. 

I've tested my motor in a full 5 gallon bucket before and was able to get flow. Try laying on the ground and looking up? Had to see holes with a black motor.


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## exide9922

Found the water intake, and a small piece of rubber sticking out the vent. I suspect the impeller crumbled apart :-/ time to take this thing apart and see. Oh fun, I just want to fish! Haha. Thanks for all the advice bdawg


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## bdawg

exide9922 said:


> Found the water intake, and a small piece of rubber sticking out the vent. I suspect the impeller crumbled apart :-/ time to take this thing apart and see. Oh fun, I just want to fish! Haha. Thanks for all the advice bdawg



I know the frustration. My motor has been sitting in the basement for a month because I've been too busy with fishing or life to deal with it. The garden is looking great though! Maybe once you fix your motor, you can come over and fix mine too....


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## grub_man

If it's not spitting water, the water pump is likely bad. The old 9.8 Mercs eat water pumps (impellers) like candy. When you turn them off with fuel in the carb, it will trickle down and eat the water pump. Once you replace the water pump, pull the fuel line when you load the boat and run it out of gas. The water pump will last much longer, or buy several water pumps and the key that holds them to the shaft. If you drop the key, you are out of luck.


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## MassillonBuckeye

grub_man said:


> If it's not spitting water, the water pump is likely bad. The old 9.8 Mercs eat water pumps (impellers) like candy. When you turn them off with fuel in the carb, it will trickle down and eat the water pump. Once you replace the water pump, pull the fuel line when you load the boat and run it out of gas. The water pump will last much longer, or buy several water pumps and the key that holds them to the shaft. If you drop the key, you are out of luck.


I'm not you have to go this far. If you premix, this shouldn't hurt anything. If its oil injected, I wouldn't recommend it. Water pump should be replaced every 2-3 years anyhow. Gas should not be getting into your pump housing and everything either. The pump has seals above and below that should prevent most anything from getting into there?


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## grub_man

It shouldn't get there, but in the old 9.8 Merc, it was very good at it. Without running it out of gas, it would go through a water pump in about 6-9 months. The ones that I knew that did it have been replaced with newer motors for quite a while now.

That old Merc did run like a champ. After a water pump going bad in Canada and losing the key during the repair, it got replaced with a 2004 2 stroke 9.9 Merc that has been running well ever since.


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## exide9922

grub_man said:


> If it's not spitting water, the water pump is likely bad. The old 9.8 Mercs eat water pumps (impellers) like candy. When you turn them off with fuel in the carb, it will trickle down and eat the water pump. Once you replace the water pump, pull the fuel line when you load the boat and run it out of gas. The water pump will last much longer, or buy several water pumps and the key that holds them to the shaft. If you drop the key, you are out of luck.


well I ordered that impeller earlier in the week, should be here by monday. hope it come with that little key you're talking about and i've seen on the youtube video's. if not is there anywhere local canton/akron area that would have impeller's/keys?


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## grub_man

The ones I had in a sealed bag did not come with a key. It might be a crap shoot to find a key. Give some folks in the area that work on Mercs a call, and check.


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## RJohnson442

You can find them at lowes and home depot and cut to size.. they have the half moons as well if thats what it takes also


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## bountyhunter

I,ve used the old key as long as it looks good. make sure you put things back 5he way they come out. put a dab of grease on the key to hold in place.


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## c. j. stone

exide9922 said:


> opening that helped it to start, but it's not spitting out water. I believe i have the motor in a deep enough bucket... Someone mentioned the impeller might need replaced? I guess i need this motor to start spitting out water first. I found the hole where the water is supposed to come out, but where does it take it in?


If you start your motor in a bucket of water, it will need to "heat up" before the <thermostat> "opens" allowing water to flow up and thru, then out the pee hole behind the engine. When it cools down, the thermostat should close-no water coming out! The engine is designed to run at a constant nominally "warm" temperature-not Hot! Your car runs the same way, thermostat opens when needed-without a thermostat in your car, you would have little, or no heat! If water runs thru the o/b engine constantly, you have no, or a stuck!, thermostat and your engine is not running at "design" temperature. Don't expect water flow thru the engine at first starting!!


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## c. j. stone

MassillonBuckeye said:


> I'm not you have to go this far. If you premix, this shouldn't hurt anything. If its oil injected, I wouldn't recommend it. Water pump should be replaced every 2-3 years anyhow. Gas should not be getting into your pump housing and everything either. The pump has seals above and below that should prevent most anything from getting into there?


Plus, if gas can get into the pump housing, water can get into the carb!! This can't happen unless some seals are broken, or not put back in place. It is still a good idea, IMO, to run the carb dry at the ramp if using mixed ethanol gas. I always do it, even in my two stroke yard equipment(which sometimes requires draining the fuel tanks if no shutoff valve)! Repair bills are almost nil.


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## Popspastime

A 9.8 engine is an older vintage motor, the 9.9's came later. When you start the motor it should start running water in seconds after it starts running, If not you need a new impeller pump...period. Now lets address the gas in the water or exhaust. If you flood the motor trying to start it, it will come out the exhaust with the water and you will see fuel floating in the water, perfectly normal. Water in comes from the cuts in the lower unit and is pumped up into the engine and exits the rear right as it circulates.


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## exide9922

Yeah it did that too, the gas in the water, but I know I flooded it by that point. Impeller should be here tomorrow. Can't wait to get this thing fixed and use it


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## exide9922

Well I was able to replace the impeller myself but it still didnt push water out after that. I suspected after more research that the water line was clogged under the powerhead where the water comes up. seems to be a common issue with these merc 9.8's. There is a washer there, that is known to melt if overheated. sure enough it was melted and plugging up the water line.after about a month of fooling with this thing I finally had to looked about by someone who knew what they were doing...


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## Cajunsaugeye

That usually ends up being the best way.


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## bdawg

exide9922 said:


> Another motor question, on my other motor. Got this mercury 9.8 with the boat I bought. Tested it in a large bucket in my garage, seemed fine. Took it out on the lake yesterday and it went a few hundred yards and shut off. Got it started a few more times and it did the same thing. Had trouble starting it back up after it would shut off. Could it need a new spark plug? Fuel filter? I don't know much about motors. Any help would be appreciated


Who did you take your motor to? I still need to get mine fixed and it might be the same problem. I'm in the Akron area too.


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