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Nissan NS40C bog down when giving gas

Vikinghawk

Vikinghawk

New member
Hello, I am glad I found this forum. Hopefully I can get an answer and get my boat on the water and take my son fishing. I am having a problem with my "New to me" Nissan ns40c outboard motor (S/N: 361A-166659) bogging down when giving it gas. I have replaced all fuel lines, purchased a brand new gas tank, cleaned the carb, & ensured there is spark. I don't know what else to do.

I am not a mechanic and I don't know anything about carburetors. I have taken out all of the Jets and plugs and sprayed carburetor cleaner through all orifices, and it still bogs down. It idles just fine. There is only one carburetor adjustment screw. Does that mean that once all jets and plugs are snugged up, you only adjust things from the one screw? I dont need to adjust the other jets?

Thanks in advance for any help!
 
Yes. There is the idle stop, and the adjustment screw. That's all.

You did Not clean the carb; you made it shiny. Proper cleaning requires complete disassembly, an overnight soak in carb dip, and then finally a blow-out with generic carb spray.

Go back to basics. Clean the carb properly. Make sure the fuel pump is delivering well. Verify timing. Check plugs. BP7HS. What do the plugs look like?
 
pvanv said:
Yes. There is the idle stop, and the adjustment screw. That's all.

You did Not clean the carb; you made it shiny. Proper cleaning requires complete disassembly, an overnight soak in carb dip, and then finally a blow-out with generic carb spray.

Go back to basics. Clean the carb properly. Make sure the fuel pump is delivering well. Verify timing. Check plugs. BP7HS. What do the plugs look like?
Click to expand...


Thank you pvanv. I should have mentioned, I also just replaced the fuel pump as well. The spark plugs I have are B7HS10, and are brand new. They are a little wet and oily when I inspect them. Are the plugs i have not correct? What does the "p"stand for?
So you are also telling me to have the carb cleaned again the proper way, make sure all jets, plugs, and needles are snug, and there are no adjustments to be made other than the idle stop and the one adjustment screw? I kept talking to people that told me each jet needed to be turned out about a turn and a quarter or so first even though I told them there was only the one adjustment screw.
I have not looked at the timing. I will check into that as well.
Thanks again.
 
The P plugs have Projected Tip. They run a little hotter at the tip, and stay cleaner longer. Yours should be OK.
Whatever idiot told you to leave the jets loose is no one to listen to about carbs.
 
Hello There.
I live in South Africa, and just bought a M40C, branded Tohatsu over here. I currently have the same issue. Did you manage to resolve yours? Unfortunately, a backyard hack worked on my motor with previous owner. I reset all the timing and carb settings. I will be replacing the plugs with new today.(had B8 plugs in....) The thermostat is also missing (waiting for new one) so I am sure I won't be able to get the motor warmed up to check properly. If there was anything else you did, then I can carry on while I wait for the thermostat. (I used to own and repair old Land Rovers, and people removing thermostats really irks me.... If you really really have to, then remove the inside and leave the ring part to restrict the flow to open operation at least)
 
Just got my boat back and the issue with my Nissan NS40C outboard. It ended up being my CDI box, or "Power pack" as my mechanic called it. Runs great now.
 
Vikinghawk said:
Just got my boat back and the issue with my Nissan NS40C outboard. It ended up being my CDI box, or "Power pack" as my mechanic called it. Runs great now.
Click to expand...

Thanks for feedback. I opened my carb, and just closed it again. Looks like some hack had a go at the jets with a chain saw. Send it straight to agents. They saying parts might be an issue. Let's see. Don't want to throw good money after a bad motor, but would really like it to run properly. It is so much lighter than the Mariner I have.
 
345032511MMAIN JET #220

345032530MMAIN AIR JET (#220)


345032550MPILOT AIR JET (#110)

345032660MADJUST SCREW


These are all available in the US.
 
I have a 92 Nissan NS40C. I've taken the carb off and apart, dipped, soaked then reassembled. I do not know the adjustments needed for ther adjustment screw. Upon pushing to full throttle, it seems to "bog" or a "sputtering" Had a helper to cover ther plastic piece on carburetor for 5+ or so seconds then it came up. Are there any adjustments for main jet and what is the starting adjustments on adjustment screw? What's the fuel pressure supposed to be cooking out fuel pump? What's the voltage to be coming back while engine running to keep batteries charged? I have 7 kids and they all enjoy riding and fishing with daddy ....... can't really do that until I don't have to worry about it leaving us stranded if we go down river....I have email, text and call for whoever could possibly help!!!!
 
Main jet is fixed; no adjustment.
Mixture screw should be set where it was; failing that, start around 2 turns out.
Expect charging system to biuld to about 14 or so volts while on the battery.
 
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