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Nissan NS5B 5hp Quit Running

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Wavo24

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My NS5B longshaft with internal has quit running. Fully disassembled and cleaned carb including jet removal etc. I am very diligent about running the engine dry over the last few years since I have owned the outboard. Now, the motor will fire up with no problem and run for about 30 seconds and then just die. Since I reinstalled the carb, the motor will only start and run for a few seconds when I spray starter fluid into the air intake. The interesting thing is I loosened the float bowl screw today and there's no fuel in the bowl. I removed the fuel line from the pump body and fuel was flowing at a good clip. I replaced diagram A and B in the pump body a few years ago. Is it possible that the diaphragms can go bad and not allow fuel into the carb? I did a visual inspection on the diaphragms and they looked "OK" but I don't have anything to compare it to.

One last note, I replaced the NGK plug with the same plug early this year and have had no issues. The engine has run great until 2 weeks ago.

Looking foward to to everyone's thoughts.
 
Just a thought! running engine dry of fuel every time,maybe diaphram has been dried out.rubber seems to swell when exposed to gas
 
Johnny, you have no clue. Sorry, but you are completely unfamiliar with that model. I know your intentions are good, but you just plain don't have any experience with servicing these motors. With E10 gas, it is requisite to run the carb dry at the end of each day.

Wavo, You are definitely not getting gas to the carb bowl. So the flow is being stopped somewhere between the tank and bowl. There is a fuel cock at the tank, and that was originally supposed to have a filter strainer pointing up into the tank. That could be clogged, but then you would not get gas at the inlet to the carb/pump. You could also have a stuck float valve, or crud in the pump.
 
pvanv said:
Johnny, you have no clue. Sorry, but you are completely unfamiliar with that model. I know your intentions are good, but you just plain don't have any experience with servicing these motors. With E10 gas, it is requisite to run the carb dry at the end of each day.

Wavo, You are definitely not getting gas to the carb bowl. So the flow is being stopped somewhere between the tank and bowl. There is a fuel cock at the tank, and that was originally supposed to have a filter strainer pointing up into the tank. That could be clogged, but then you would not get gas at the inlet to the carb/pump. You could also have a stuck float valve, or crud in the pump.
Click to expand...

Thanks for the ideeas. I replaced the fuel cock a few years back but it could certainly be clogged. I am going to disassemble that as well, inspect and clean. On the diaphragm topic, is there a way to determine if they need to be replaced? I replaced them a few years back.
 
The fuel pump diaphragms could be bad, but I would expect gravity to push fuel past them even if only a slow flow. You could have a stuck valve in the pump, or a stuck float valve.
 
My 2004 Tohatus had the same problems. After cleanin g the carb one last time I was careful to catch the contents of the fuel bowl and there were small specs of black gunk. Replaced the fuel lines and the engine has run flawlessly for 6 weeks! Good luck
 
Problem solved! I installed all new fuel pump diaphragms and gaskets and the engine fired up on the 3rd pull and is running great. I also switched the fuel to the ethanol free 50:1 pre-mix as I am wondering if the ethanol damaged the diaphragms over the last few years even with running the engine dry each time.
 
My 40D2 quit, then it stated up after 20 min later, I held choke in and throttle half way hard grind start. at the dock it started up 3 times.
3 hours later as it set, no start again.. today it stated. then set, for a hour..no start again.....any ideas>? Fuel pump ,or float stuck.? Took off carb cover saw gas dripping down ports... ?? Plugs ? help
 
swest77, Start a new thread on your own.you will get more responses, Sounds like she's flooding, pull plugs,inspect them, Wet? Dry? Troubleshooting starts with a compression test,followed with an open air gap spark test,then last fuel diagnostics,in that order
 
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