Spark plugs

"I took my BF15DK out today an

"I took my BF15DK out today and while warming the engine, it began to run on 1 cylinder. I let it run on 1 cylinder for about 15 seconds to see if the other cylinder would recover. It only picked back up when I slightly revved the engine. When I got back home, I pulled the spark plugs and they looked fine. The plugs are Denso and I am wondering if I should go ahead and try new plugs. I have had poor idling on this motor when cold ever since day 1. Are the NGK plugs better that Denso on marine engines? This engine has very low hours and was purchased March of '09. Thanks in advance for your help!"

"You see and hear a lot of jui

"You see and hear a lot of juice about one plug being better than another but I work with both Denso and NGK and really couldn't answer your question based on my experience because they both seem of equal quality to me. And, when you look at what a spark plug actually is, there really ain't much to screw up anyway. Electrode in an insulator in a threaded body with a ground tab. Simple. If it works for one minute, it will probably work for 300 hours.

New plugs every season is a great idea and, if I'm using my money, I buy the NGK because I really like the box they come in;~)

Keeping the high tension side of the ignition system fresh makes it easier on the coil and magneto system. If I were you, I would unscrew both spark plug wires out of the coil and look very carefully in the coil towers and at the ends of the wires for signs of arcing and overheating. If you see a coil tower (place where the wire screws in) with what looks like rust at the bottom of the hole or the end of the wire looks rusty, that could be your misfire. Left alone, the coil will fail because of the arcing taking place at that interface. Clean the inside of the tower with contact cleaner and carefully swab it out. Replace the plug wires.

I recommend changing the plug wires every other season unless the boat is frequently used offshore and then I suggest every season when you do the water pump impeller."

"Good advice all around from J

"Good advice all around from Jimmy.

However, I have had two different dealers independently tell me that they believe the NKG plugs are better and are less likely to fail during normal usage."

"And they see a boatload more

"And they see a boatload more outboards and spark plugs than I do every year so their advice should probably not be ignored.

I work on cars and trucks in addition to outboards and I am a member of THE international technicians group, iATN. In the last few years, the BOSCH spark plug has really gotten a bad reputation with a large percentage of automotive technicians. I've personally never had a problem with any of their products. Robert Bosch invented the Lambda sensor (oxygen sensor) for Pete's sake! You would think they could get a lil' ol' spark plug right!

But, based on testimonials from all these guys I am in league with at iATN, I find myself shunning the Bosch plugs in lieu of other brands when at the parts counter.

Thanks for the input WD. Now I have another reason to buy NGK other than the cool looking box."

"Jimmy has good advice on cutt

"Jimmy has good advice on cutting the wire ends. That has fixed many a problem on Evinrudes, Nissans, etc... however the Bf15Dk has molded spark plug connectors. They and the wires are one piece with the coil.

It has been my experience that Denso plugs do seem to have more issues than NGK. Many of the Hondas are shipped with Denso plugs. However, if one comes in with a running issue that may be ignition related I always change the plugs out to NGK.

What do the plugs look like? Is the bottom one oil fouled? If so, you may have too much oil in the engine. The oil levels on those engines should be a little below full, measured with the engine vertical. They tend to bog down and run bad if overfull."

"Both plugs were clean and dry

"Both plugs were clean and dry. I checked the gap and both are @ .031", so everything appears ok. I am not a plug analyst, so here is a pic. I had to resize pic to upload. If you need a bigger pic, I can e-mail one. "

"The easiest thing to try is c

"The easiest thing to try is change the plugs.
This is assuming the problem is ignition related.

If you have a timing light, you can put it on each plug wire to see if you are losing spark on one of the plugs. If it continues and you are losing spark, then it is probably a faulty coil/wire assy. You would have to take it back to the dealer for warranty repair.

If the motor is s manual start, you could pull the choke out a little (actually a fuel enrichener) to see if it helps the idle. If it does, then you have a carb idle circuit problem. If you have an electric start, you will not be able to do this.

A carb issue is normally not covered by warranty unless there is a manufacturing defect. If this has been a problem since day one, you can try to make a convincing story that it has always been that way."

"I will change the plugs with

"I will change the plugs with a set of NGKs. It is an electric start and once the motor has warmed up, it idles and runs flawless. I tried adjusting the idle adjustment at the carb, but put it back to the original setting. Thanks again!"

"If the motor is starting ok a

"If the motor is starting ok and runs at a higher than normal idle, reducing to normal idle in neutral when it warms up...it sounds like it is running ok. Until it warms up, it is running rich and will probably bogg down if you put it in gear and put power. That is normal for that engine.

All may be ok."

"This motor does start fine an

"This motor does start fine and then will bogg down in neutral before putting into gear (only when it is cold). After the motor has warmed, I do not have any problem. Is the enrichner computer controlled and what does the idle adjustment screw do exactly? When I changed this adjustment, I did not see any change. I am picking up the NGKs tomorrow and will see how they perform. Will report back as soon as I do a test run."

"Without advancing the throttl

"Without advancing the throttle...does the engine start at a high idle then slow down?

You should not advance the throttle for starting.

The enrichener valve is controlled by 12v being applied to the enrichener as the engine is running. When the engine is cold, the valve is open, which allows more than normal fuel to enter the combustion chamber. As the valve (and the motor) warms up, it closes down the valve and only allows normal fuel flow. Thus, the engine starts at fast idle then slows down.

If the engine does not start at a faster than normal idle then slow down, there could be a blockage in the enrichener circuit.

The carb has two idle adjustments. One is a screw (reached from the rear of the engine) which is an idle stop and controls the speed of the engine at idle. The other is an idle mixture screw (on the starboard top side of the carburator) which has a shiney plastic cap on it, which severely limits the adjustment of the air/fuel mixture at idle. Turning this counterclockwise will increase the fuel flow at idle. You probably will not see much change if this is what you adjusted.

The plugs probably are not the problem...but it would be good to change them anyway...just in case.

One other thing that would be good to check, would be to drain the fuel in your carburator into a glass jar to check for water in the fuel. It probably is not the problem, but it is easy to eliminate from the equation."

"The motor has never started a

"The motor has never started at a faster idle then slow down. This must be my problem. When I picked up the motor at the dealership in March '09, the salesman instructed me to twist the throttle grip three times before starting to activate the enrichener. The motor would run at slow idle for 20 to 30 seconds then bogg down. On other days, I tried just pressing the start button without twisting the throttle and the same thing happened. After the motor would bogg down, it would start right back up and then I would have to "baby" the throttle to get it warmed up. So it sounds like I have an issue with the enrichener operation. Sounds like I may need to take it in for service, huh? I got the NGKs today but I haven't had a chance to install them."

"The carburetor probably needs

"The carburetor probably needs cleaning. As Mike said, the enrichment valve is open when cold and then slowly closes the passageway as it warms up electrically. The engine should start at a pretty high idle and then settle down in about 60 to 90 seconds depending on ambient. I've never seen a valve go bad but I've cleaned lots of carb bowls that had symptoms like yours due to mineral deposits from water in the fuel. All fuel, no matter how well it's filtered, will have some water in it. That's why it's cheap insurance to always drain the bowl before putting her to bed."

"It does sound like a blockage

"It does sound like a blockage in the enrichener circuit. When you twist on the handle, you are activating the accelerator pump, which shoots some extra fuel into the carb. If the carb was operating properly, that twisting would flood the engine.

I do not know how long it has been since you bought it, but it would be good to take it back and see if they will make it right. Normally, carb issues are not covered under warranty, however, it sounds like it probably was not working right since you got it. Twisting the throttle grip is a way to get it started if there is an issue with the carb...but the manual says to start it without advancing the throttle.

I would hope that they would at least give you a break on the labor to fix it.

Also, Jimmy made a very good point, that it is good to drain the carb, if you are not going to use the motor for more than a couple of weeks.

Also, you should always use some sort of fuel treatment like PRI-G, Sea Foam, Stabil Marine, etc in your fuel to miminize deterization of the fuel and keep the jet and passages clean in your carb."

"Yeah, listen to Mike. Go back

"Yeah, listen to Mike. Go back and see if that salesman still works there and get him to tell you how to start the engine IN FRONT OF THE SHOP MANAGER. If it's an honest dealership and an honest shop, they should make it right. I'm not familiar with your exact model, but I take twin cylinder single carbs off, tear them down, clean them,re-assemble, put them back on and tank test them in around an hour. No big deal. A LOT of carb spray, (can't immerse them due to the plastic)a couple of new seal rings, gaskets and viola, just like new. If they want to charge more than an hour's labor, negotiate for paying some of it along with "consumables". It will be worth an hour's labor rate to you to have the engine fire up and purr like it was designed to do.

You might want to print the back and forth here to show to a "supreme being" at the dealer to help your cause. We love HONDA outboards here! We would not tell you to screw a dealer. But, by the same token, we don't like it when one of their employees gives you bad info or service. That's why the guys on this site want to help the owners.

The Honda hardware is superb in this industry. My opinion is that you can't buy a better motor. So, it comes down to people and policy to keep 'em running happy.

And remember, Honda put that fuel bowl drain tube and easy access drain screw there for a reason...use it."