Nissan 9.8 Idle/choke problem.

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casperc

Cadet
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Jul 1, 2002
Messages
10
My 2004 9.8 will not idle, starts fine with choke, will idle forever with full choke. (15 min or more) When I try to reduce the choke, the engine speeds up and dies. It will run at higher power settings.<br /><br />Initially I suspected a gummed up idle circuit, and ran some carb cleaner through the gas. I did get a subsequent good idle, but on return from a sail the motor would not idle off choke again, More carb cleaner did not change anything.<br /> <br />The motor had spent 2 weeks at a dealer getting a steering tension adjuster repair.
 
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casperc

Cadet
Joined
Jul 1, 2002
Messages
10
Re: Nissan 9.8 Idle/choke problem.

The engine has about two hours on it, is the thermostat a possibility?
 
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casperc

Cadet
Joined
Jul 1, 2002
Messages
10
Re: Nissan 9.8 Idle/choke problem.

Thanks Elvin,<br />Taking apart the carb, cleaning and putting it back, resulted in an acceptable idle. There was no evidence of varnish or residue in the carb, it was squeaky clean, except for the bowl gasket which had a grayish brown residue on it (sealer?) but no evidence of that in the carb bowl. At first the idle would die, but after a while it cleared up, perhaps due to residual carb cleaner.
 
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Hunter22

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Aug 2, 2005
Messages
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Re: Nissan 9.8 Idle/choke problem.

I just got a new 2005 9.8 Nissan and have the same problem with rough idle. How is it possible for a new carb to be dirty? The type of gas? I've owned many outboards and never had this happen. My motor has about 10 hours. I'm not doubting the dirty carb but I'm curious what would cause it and if that's indicative of a 4stroke and/or Nissan. Also if this is a reoccuring thing. Thanks
 
TOHATSU GURU

TOHATSU GURU

Admiral
Joined
Jul 22, 2004
Messages
6,164
Re: Nissan 9.8 Idle/choke problem.

It only takes one little, tiny, passage in a carb to cause a problem. It can happen with a new engine in a heartbeat...all it takes is one small bit of foreign matter in a carb to ruin your day. The most modern four-strokes are more prone to carb problems than older ones. The problem crosses brands and is a sign of more required maintenance for small four-strokes. It sucks when it happens, but if you run the gas out of your engine, like you should be doing, each time you are done for the day, you shouldn't have to do it but every couple of years.
 
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dfloeter

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Sep 10, 2010
Messages
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Re: Nissan 9.8 Idle/choke problem.

My 9.8 has a dirty carb and is in need of a rebuild kit. So far I have not found one and hope maybe the Guru himself might know where I can find the elusive 3V1-87122-0.

His advice has been right on the money before. When we were on Andros in the Bahamas I had the carb apart several times and even had the chief naval engineer from the nearby US Navy base take the carb back and clean it at his shop but still it would not run well. The Guru's advice to look at jet 1-6 was the ticket and it ran well for the next year until another piece of gunk settled into the spot.

Now the float bowl is covered in a yellow dust, the needle valve appears to have a pealing paint job and gas gushes out the over flow on the top of the carb when I try to run it. Enough with the ranting.

This list is very helpful and I appreciate the info.
 
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whiskerpole

Recruit
Joined
Jul 2, 2008
Messages
2
Re: Nissan 9.8 Idle/choke problem.

I can see daylight thru all 6 ( i think) in the holes in the brass and have even had a dealer look at it...and it just
won't idle. It has a whopping 10 or so hours on it. Every time I give it gas, it sputters and dies. I revs great
when it's running at higher rpm's. If it weren't for the gas smell, I think you could eat off this carb. What could
be the problem ? It also has a "hi pitched whine" at certain rpm's. I've replaced the fuel fiter, cleaned the fuel
pump and carb, stabil in the gas...even changed the oil...but it still won't slow idle...it never has for more than
a few minutes.
 
pvanv

pvanv

Admiral
Joined
Apr 20, 2008
Messages
6,569
Re: Nissan 9.8 Idle/choke problem.

Still sounds like a carb issue. Probably in warranty, as long as it's not a situation of a dirty carb (which would be considered abuse), the warranty should apply. After all, carbs are covered under warranty. BTW, you can't see daylight through the idle/pilot passage under any circumstances. Also check the oil level. At 10 hours, you should only fill it about half way or maybe 3/4 on the dipstick, as the motor is probably still "making" a fair amount of oil from blowby. If you overfill it, even a drop, that will contribute to these kinds of symptoms to a degree.

Have you religiously run the carb dry at the end of each day? When you cleaned the carb, did you do a complete disassembly of (both high speed and idle) jets and emulsion tube, as well as both covers/plates, followed by a proper 4-hour soak in real carb dip, such as Tyme, followed by a blow-out with either carb spray (preferably) or compressed air? Did it idle OK when it came out of the box? If it ran OK at first and doesn't now, something has changed, likely in the low-speed passages of the carb.

Have you discussed the idle problem with your dealer? If so, what did they recommend?

I have seen (heard?) a few 9.8's that whine a bit somewhere around 2,000 RPM. In fact, my personal motor does it a bit. Not 100% sure whether this is a timing belt whine, or possibly an intake harmonic. In any event, the whine is not damaging, and is not a sign of anything "wrong". The reason you can hear the whine is because the motor itself is fairly quiet. If the motor was louder, you probably wouldn't be able to hear the whine. Typically that sound will go away after the motor is broken in some more.
 
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