Poor or no Idle on Nissan 9.8 hp 2006

"I have a 2006 Nissan 9.8 4 stroke, which has constantly been having problems with the 10%ethanol added gas. I have had to change the fuel line between the fuel pump and the carb, every spring for the past couple yrs. because of fuel leakage. It seems that in addition to attracting moisture, the ethanol swells and softens the line. Most recently the motor developed a problem where it would'nt idle. I disconnected the fuel line, where it usually leaks, and pumped some gas into a container,and found water droplets . Took the gas can back home, dumped it into my truck, and air dried the tank for a day. I returned to the boat, took the carb off and apart, visually checking all the jets and verified all accessable machined holes where open, put it back together, flushed some fuel thru using the primer bulb thru to the line I'd taken off just before the carb, pumped about 8 onces of gas into a container, and reconnected the fuel line. After priming the carb, the motor started right up, and would idle just fine. I used the motor on and off for the rest of that day. The next day, the problem returned. I spoke to my mechanic, and asked if it could be the fuel pump is weak, he suggested the carb could still be dirty, particularly behind the idle jet, which is located behind a factory installed brass plug. I had to agree, as that is the only location which I could not verify was clear, without removing the brass plug and idle screw. I've drilled out the plug, and removed the idle screw and now have verified the passage way is clear.
I will be installing the carb this labor day weekend, I'll reflush the lines, and report back.
Im still looking for a fuel line that can handle the ethanol. I read somewhere that the ethanol wont effect the fuel injection type fuel lines.
Can anyone confirm this? I suspect the ethanol,or the Startron additive I've been using to combat the moisture, is causing the fuel lines to deteriorate from the ID wall, and that debris collecting at or around the idle screw causing a fuel blockage.


Rick"

That line shouldn't be rea

That line shouldn't be reacting to 10% ethanol that way. Contact Tohatsu at 972-323-6003 and ask them what they think. I suspect that your fuel source may be a little off on what the % is. I've seen fuel doctored as high as 22% and sold as 10%. Your theory on on the debris is very likely.

"Thanks for the quick reply,

"Thanks for the quick reply,

I did some further investigating using some equipment at work, and pretty much identified what gets clogged and causes idle problems on my 2006 Nissan 9.8

I put the dis-assembled carb under a microscope and found some more contamination, the worst was around the low speed jet housing, its cap, and the thru hole of the low speed jet itself. I sized the jet using a series of gage plugs, and found the hole was constricting from build-up like a clogged artery. I took close-up pics using the scopes camera.

I also found contamination build-up on the idle
speed screw, at its flange ( the flat area before the needle) I lifted a section of this thin film up with a pin and placed it on the needle for illustration. I took photos of this also.

I'll try to post the photos so everyone else can
see just how microscopic particals build up to a cakeing crust or thin film.

I'm soaking it all in a gallon of GUNK carb cleaner overnight, and will blow it out tomorrow with compressed air. I'll try to get some after photos.


Rick"

"This is photo set 1 before so

"This is photo set 1 before soaking in carb cleaner. Nissan 2006, 9.8 dirty low speed port, low speed port cap, and low speed jet

"This is photo set 2,of the id

"This is photo set 2,of the idle speed screw, also before soaking"

"Update, Per the instructions

"Update, Per the instructions on the Gunk cleaner, I sprayed off the Gunk with water, but still had to do some light scrapping (even after soaking overnight)to clear off the scum around the entrance to the larger jet. I then used fine wet or dry paper wrapped around a drill bit to polish the O-ring area, then re-Gunked it, hosed it off again, and let it all bake in the sun for an hour.

I put the carb back together and installed it on the Nissan 9.8. As before, I flushed about 8 onces of gas thru the lines using the bulb. After connecting the fuel line to the carb, and few cranks to fill the carb, it started up. I then adjusted the idle needle screw to get a smooth idle. The best setting was 2 1/2 turns backed off from closed. Next I tweeked the throttle adjust screw to bring the idle up a bit.
Wow! what a difference! Just like a new motor!
I can rev it up and it just purrs down to a whisper.
As an added measure of protection and filtering,
I have connected a Racor RR120 water/fuel separator with 30 micron filtration, and have also added a mini-solid core in line filter in place of the original filter.( i dont want to have to do this again)

I'll add a photo of the drilled out brass plug which conceals the Idle Jet.

Hope this info helps others to get the same satisfying results I got.

Rick"

"Photo of the Carb with the fi

"Photo of the Carb with the first (pilot) hole, prior to re-drilling to 1/8 inch size in order to pry out the brass plug using the drill shank. (No Linkage)Photo of plug to drill out to access Idle speed adjust screw.

"It was unnecessary and illega

"It was unnecessary and illegal to drill out the plug. The carb cleaner would eventually have worked to remove the clog without drilling into the Federally required seal that prevents people from violating Federal EPA regulations. Any dealer who sees that the drilled access port is required to contact the EPA and report the crime...I doubt that any would ever do so, but its the equivalent of modifying catalytic converter.

It's relatively easy to avoid a severely fouled carburetor. Just run the fuel out of the engine at the end of every trip(using the choke to tickle the last bit of fuel use)."

"So what your now telling me i

"So what your now telling me is that, since I fixed the idle problem by myself that was caused by the federal govts forcing the use of 10% ethanol gas , which is well known to cause clogged carbs in everything from lawn mowers to outboards,in the process I became a Felon.

This is too much. I guess you'll have to delete all my postings, before the guys in the dark glasses and black suits show up.

Rick"

"It's more like I am provi

"It's more like I am providing the background information as to why that jet is sealed and providing a warning that it is not necessary to have access to it to clean the carb. Someone on another board told someone exactly how to get to that jet last week. That consumer then drilled directly into the jet and ruined the carb. I'm happy that you fixed your engine and I applaud your resourcefulness. But, You didn't need to go into that sealed area to clean your carburetor and I wish you hadn't gone into such detail. Also, ethanol does not cause clogged carburetors. Leaving fuel in the carburetor causes clogged carburetors. Ethanol acts as a solvent on old rubber fuel lines and absorbs water. In and of itself, 10% ethanol won't damage anything.

And yes, you are now a criminal I haven't seen you at any of our criminal meetings, but be sure and speak up at the next one. As the feds screw things up further I foresee a time when we all violate some dumb$$ law or another."

"I'll be the one in the ba

"I'll be the one in the background, singing....

wooooo,,,,Ah.......thats the sound of the men
..working on the chain... gaaa...ng."

"Bass, tenor or soprano? [img]

"Bass, tenor or soprano? "

ran a 9.8 for 1 year on benzen

ran a 9.8 for 1 year on benzene 91 -no problems and was told that the red dye used in thailand in 91 clogs up idling jets so changed to 95 and in no time the idling just gave up -I am suspicious that gasohol 20% ehanol may have been provided by gas attendant so replaced fuel again with 95-still no idling but will run at normal running revs
What do I do? service carburetor?

Clean the carb

Clean the carb