new Nissan 9.8 stalled

[RA]

Hi,

I ran my new 4 stroke 9.8 for 3 hours of the beak in period, then pulled the fuel line and let it run out of gas. The motor sat for a month while I was away. I went to run it again and it would only run with the choke all the way out, it kept stalling in gear when I tried to accelerate. I put in some sea foam and it after a while it ran fine again. The gas is premium unleaded with stabil added. The gas tank vent was open all the time. What could cause this?

Also, do you drain the fuel water filter bowl and fuel lines of gas when winterizing or if the motor will sit for a while?

Thanks for your help!

 

[pvanv]

Re: new Nissan 9.8 stalled

These motors run really lean. That requires small, high-velocity mixture passages. The emulsion tube and the idle mixture metering screw/jet passages in the 9.8 carb are particularly fine, and easily restricted by varnish and crud. This is the likely culprit in your case. This is exacerbated by running E-10 gas, which many of us are forced to use. I have had several 9.8 carbs that needed the emulsion tube and idle passages cleaned after only a few hours of run time, but several weeks of lay-up.

Sometimes, like in your case, the varnishing will dissolve overnight, or over a weekend, as long as good fresh fuel is used, especially if the new fuel has a good additive in it. Lay-up periods make things worse. We find that the more often you use the motor, and the harder you run it, the better is runs. A couple of marinas in our area have non-ethanol fuel, which seems to have a better shelf life than the E-10 blends. You may have non-ethanol fuel available in your area, but you may have to hunt for it, and be prepared to pay extra for it.

There is no need for premium fuel. Regular 87-octane works fine. As for additives, we have been using K100-MG in our personal motors, as well as recommending it to our customers, with good results. We are also using and recommending water-separating filters, which capture a surprising amount of water, or cloudy gas (containing emulsified water). The key is still to get the least alcohol, and the freshest gas available, and don't buy more fuel than you will use in a couple of weeks.

We drain the entire fuel system (lines and carb) on the motors we winterize and store. The 9.8 carb has a drain screw on the starboard side that accepts an 8mm wrench. Don't drop the washer from under the head of the screw when removing it, and don't overtighten the screw when replacing it.

 

[wigeon]

Re: new Nissan 9.8 stalled

Great advice- thank you Paul. I have the same as a kicker on my boat- will apply the new knowledge.

 

[RA]

Re: new Nissan 9.8 stalled

Thanks Paul, I will follow your advice. Do you have to remove the carb to clean the emulsion tube and jets if the problem gets worse? I bought the service manual and it seems like it would be a lot of work to have to do this repeatedly throughout the season, especially on a new engine. I will study the manual this weekend. Why are the jets so small in the marine carbs? Being new to outboard engines, I look at my 4 stroke lawnmower and it runs on the same E10 gas year after year without carb problems.

 

[pvanv]

Re: new Nissan 9.8 stalled

RA,

Yes, you pull the carb to clean it. Pretty easy on the 9.8. The main jet and emulsion tube are accessed after the bowl is off and the needle/float has been removed. You will need a GOOD screwdriver (and some carb skill) to remove the main jet/tube from the body. If in doubt, take it to a qualified carb mechanic.

The idle adjustment screw is a different matter, and EPA required a brass plug installed to cover it (so we don't tinker with it and create too many emissions). They are also the ones who require incredibly low emissions, which means lean mixtures, which translates to small passages in the carb.

Better yet, run the best gas you can, and run the motor frequently, then drain the carb if laying up for a few weeks or more.

 

[gss036]

Re: new Nissan 9.8 stalled

http://www.fuel-testers.com/is_gas_additive_safe_with_e10_list.html

Go to this page and read about contents of additives and mixing w/alcohol.
From what I get, there is no need for additives since alcohol is a cleaner any way. I was going to recommend SeaFoam, ( I use it all the time), but it does contain alcohol. I use Chevron Techron in my car engines, so I guess that too would work in outboards.