Poor Idle on Nissan 9.8 Engine

[ISWizards]

I have a 3 y/o Nissan 9.8 4 stroke, electric start. Recently, it began idling roughly, then more recently, dying at idle. I have replaced the plugs, rebuilt and thoroughly cleaned the carb, replaced the filter, and made sure the filter is remaining nearly full even as the engine gallops, then dies. I've also pulled one, then the other plug wire and discovered that it runs better with only a single plug than with both! Any ideas out there?

Thanks Much!

 

[pvanv]

Re: Poor Idle on Nissan 9.8 Engine

You didn't mention model, but I'll assume you have an NSF9.8A3, right? What method did you use to clean the carb? When it's idling poorly, will adding some choke make it run a bit better? Are you within the 3-year warranty?

Could be a number of things, but I suspect that you are running lean at idle due to varnishing in the low-speed circuits of the carb. If you didn't do a complete carb disassembly (including the jets and the emulsion tube "nozzle"), then a 4-hour bath in real carb dip, such as Tyme, you need to do that.

 

[ISWizards]

Re: Poor Idle on Nissan 9.8 Engine

Paul,

Yes, NSF9.8A3. I'm just beyond the warranty period. Adding choke does improve the idle. We did a lot of spraying and cleaning, but certainly didn't try a 4-hour bath in a carb dip. I'll see if I can track some down and try that. Does the idea of lean idle mixture correspond with it running better with one plug disconnected? I was afraid that was pointing to a timing problem.

Anyway, thanks much for the input! Off to try to find some carb dip...

Clay

 

[TOHATSU GURU]

Re: Poor Idle on Nissan 9.8 Engine

Carb cleaner dip is available at any auto parts store and if you disconnect one plug and it runs better, that's not a carb issue

 

[pvanv]

Re: Poor Idle on Nissan 9.8 Engine

Clay, Your 4-stroke has a siamese ignition coil. Both cylinders fire in time with each other, (and there is a "wasted" spark on the exhaust stroke). So ignition timing is not likely at fault. It is possible to shear the woodruff key that drives the flywheel... that would make the whole motor out of time (both cylinders), and typically results in a "no-start" or "won't keep running" condition, rather than a "won't idle" problem. A compression test and a leak-down test wouldn't be out of the question... to help track down further problems... especially if you have problems at higher RPM's, but start with the carb. Easy to get to, common problem, and definitely called for if not running dry every day.

 

[ISWizards]

Re: Poor Idle on Nissan 9.8 Engine

Thanks much for the advice! I've got some B9 carb dip on the way, and am planning a serious bath. I also noted in the manual that poor idle may be associated with a bad thermostat, so I've ordered a new one of those and the gasket. Sounds to me like I should do the soak first, given the advice so far...

 

[ISWizards]

Re: Poor Idle on Nissan 9.8 Engine

Paul, Given the siamese coil, have you got any idea why I see improvement when I'm only running on one cylinder?

 

[pvanv]

Re: Poor Idle on Nissan 9.8 Engine

Dunno. Are you running the 1-cylinder test with the plug out? If so, it's because of the lack of compression without the plug.

 

[ISWizards]

Re: Poor Idle on Nissan 9.8 Engine

Paul,

Nope, just pulling the plug wire (during which I confirm a healthy jolt of electricity!)

 

[pvanv]

Re: Poor Idle on Nissan 9.8 Engine

If you are out of time... have a sheared magneto key, or if the timing belt is off a couple of teeth, this could happen...

 

[kwjennings]

Poor Idle on Nissan 9.8 Engine

I have been having the same problem for the past 6 months. I believe that my motor model NSF9 8A3 S/N 046258XG is a 2006 model though it has not seen a lot of use. That being said it has been regularly maintained by a Nissan outboard dealer in Ontario.

In June of this year we visited Stuart Florida as we toured America's great Loop www.greatloop.org, In Stuart; I told the local Merc, Yamaha, Suzuki dealer that my outboard was not idling well or sometimes at all. I spent more than $381 for a tune up that dealership. Even after that $381 'tune up' my outboard NEVER idled properly.

Today I read your thread at after reading your thread and read about soaking the carb body in cleaner for 4 hours to clean out the low speed circuits then I saw where I can purchase a complete carb assembly for about $140.

http://www.**********/parts/search/ssan/Outboard/2006/NSF9.8A3/CARBURETOR/parts.htmlNi

**********

boats dot net

2006 NSF9.8A3 Nissan Outboard CARBURETOR Diagram and Parts


What else should I check before I order the carb & spend the $$$

Ken Jennings
www.ourtardis.net
202 378 4868

 

[TOHATSU GURU]

Re: Poor Idle on Nissan 9.8 Engine

The correct way to do this is to diagnose that the fuel system is the problem before you start spending money on parts...Having said that, you have a 90% chance that the fuel system is the problem and a further 90% chance that the carb is just dirty. So, you can have it correctly cleaned or buy the carb...If you want the carb, Paul will sell you one.

Quick question, what did they claim that they did for the $381.00? There isn't any tune-up on that model engine as the ignition parts can't wear. Other than cleaning the carb, changing the oil(s) and putting in new plugs...About $150.00 at our dealership(and we are high), there isn't ANYTHING that would be done.

 

[pvanv]

Re: Poor Idle on Nissan 9.8 Engine

Gotta agree with Elvin. What on Earth was done for over $380.00?

We do full winterization on those motors for less than 1/2 that cost. That includes changing the oil(s), blowing-out the fuel system, greasing and oiling linkages as needed, inspecting everything, etc., and then, after winter storage, a 20-minute "spring prep" tank test to verify proper operation. If they need extra-cost services, such as WP repairs, spark plugs, carb work, etc... of course that's additional. Point is, there's really nothing to "tune" on those motors.

Yes, you probably have a fuel system issue, and yes, it's probably a dirty low-speed circuit in the carb... and yes, it can probably be rectified by a thorough and proper carb cleaning. BUT... you need to diagnose first. If you elect to replace the carb, you need to understand that you will need to order the correct part: Depending on your specific model configuration, your motor may call for one of two different carburetors. The Remote models use a carb which accommodates the electric choke system, whereas the manual choke carb is for the tiller-steered models. They are not interchangeable.

Again, diagnosis will tell the tale. For example, if you are even slightly over-filled with oil, idle will suffer. Or... if the thermostat is jammed open (running cold all the time), idle will not be as good, and plugs will foul. For that matter, if you have poor fuel delivery, with lots of air in the system, it might not idle well, either. Point is, your issue could still be a lot of things, and just "throwing parts at it" will eventually fix the problem, but will be the slowest, costliest manner to do the repair.

 

[kwjennings]

What was done for $380?

What was done for $380?

Here attached is an invoice from the dealer in Florida that did the work on my 9.8.

As you read this REMEMBER that my only COMPLAINT was 'The engine Runs Rough or not at all at Idle. Does it need a Tune up?'

They may have tuned it up but they did not correct the main complaint.

$12.50 for 1.5 qts of oil is a bit much too. I can buy drinkable dark rum for less than that! Pretty expensive thermostat too.

 

[pvanv]

Re: What was done for $380?

Re: What was done for $380?

The retail price on 10w-40 FC-W oil is running about $8.00 a quart, so that price isn't out of line. BUT, it is IMPOSSIBLE to pour more than about 1.5 PINTS of oil into that crankcase without severely overfilling it. THAT in and of itself could cause a very poor idle, and a host of other, much more severe problems. OTPH, perhaps they changed the oil twice, to flush out the crankcase. Dunno. The pricing on the rest of the parts is normal, as well. Outboard bits are pricey, due to supply-and-demand, and Tohatsu parts are a lot lower priced than the equivalent Tohatsu/Mercury or Tohatsu/Evinrude parts.

If the temperature of the motor was normal, there was NO REASON to replace the thermostat. Likewise, if the motor was flushed after every saltwater run, it is very unlikely that the anode needed to be replaced.

They did not do anything to "tune" the motor -- aside from changing the plugs -- and they certainly didn't list any carb cleaning or idle speed adjusting work. It was probably prudent to replace the wp kit, so no beef there. In short, they mostly did work you probably didn't need, and ignored what you requested. Pricing, while a little steep, is not out of line for what they did. Too bad they didn't address your problem.

Diagnose the problem.

If it's determined that the fuel system is lean at slow speeds, either clean the carb properly, or replace it. In the future, religiously run the carb out at the end of each and every day, to reduce any varnishing problems.

 

[kwjennings]

9.8 Idles perfectly now thanks to Morgan from Whale Creek Marine

9.8 Idles perfectly now thanks to Morgan from Whale Creek Marine

I am in Cape May NJ. Yesterday I called the local Nissan dealer Whale Creek Marine and explained my frustrations & problems with idling.

One hour later Morgan the owner and a well trained Nissan mechanic was here on the dock with me checking out my motor. Morgan quickly determined that the carb was the problem. He removed it, cleaned it and rebuilt it on the dock and while doing that he patiently explained to me how he was doing it and what to watch out for if I had to do it again myself. 45 minutes later the card was reinstalled & tested on the dinghy. it runs and idles purrrrfectly.

Happiness at last! Now we can go to NYC and pick up a mooring at the 79th Street Boat Basin. WooHoo

Thanks guys for ALL of the GREAT help & sharing of knowledge. Special Thanks to Morgan for delivering us from the frustration that we were suffering from.

This winter I will install a primary fuel filter / water separator on the transom of the RIB. I promise to always drain the carb's float bowl beore leaving the engine for any-time more than 30 days.

Here is a link to Morgan's website

http://www.whalecreekmarina.com/


Ken Jenings
www.ourtardis.net
202 378 4868