Mercury 200hp Xri 1992 Idle Problem

[skigolfnut]

After Putting In 2 New Switch Boxes, New Stator, New Fuel Pump, Etc.. Boat Runs Great For About The 1st Hour Pulling Skiers, Then Starts To Act Up At Idle, Stalls Out, Wile Ideling For Skiers To Get Ready, I Just Turn Off And Wait Until The Skier Is Ready, Start- Put In Gear And It Goes, A Little Sluggish Out Of The Hole But It Will Go. 2 Hours Go Buy Then Back To Normal, Ideling Fine No Cutting Out, Great Hole Shot For Barefooting, Then Another Hour Goes By Then Back To Cutting Out Ideling, If I Pull Neutral Warm Up Switch Out It Will Run Fine While I Am Waiting On The Skier, But Then It Dies By The Time I Try And Put It In Gear, It Is Easier To Just Start, And Put In Gear And Go, It Will Run Good 58-60 Miles An Hour Even When It Is Having The Idle Problem, Any Ideas???

 

[ElectrixBass]

Re: Mercury 200hp Xri 1992 Idle Problem

I have a 93 200 xri with exactly the same problem. It seems to start fine in the morning but then starts having idling problems. Seems to be missing a bit but gets on plane well and seems to run OK. Something is however just not right....the sound, the powers just not quite right and like you say will not idle after that first run in the morning.

Doesn't seem to be bad gas or a leak in the lines. The spark plugs are the center electrode kind and don't seem to be fouled or wore excessively. I haven't checked the spark at each plug.

Any thoughts yawl.

 

[CharlieB]

Re: Mercury 200hp Xri 1992 Idle Problem

I imagine that you both are running the stock oiling system.

Take a close look at the oil pump setting, you may be too rich on oil at idle, loading up and fouling spark plugs, yet perfectly fine well off an idle and above.

Hopefully you are using NGK BUHW and if your ignition is hot enough for the additional gap the BUHW-2

 

[skigolfnut]

Re: Mercury 200hp Xri 1992 Idle Problem

My oil pump has been disconected long ago, We do a lot of barefoot water skiing and run about 42 mph all day, so I have been mixing the ratio 50-1, but the last couple of times out it has just been with the little ones so 10 mph tops, I am afraid to mix it any leaner for top end? I am running the NKG-BU8H that mercury recomended, the motor only has 850 hrs good compression, should I try the hotter plug? Some one even suggested I take the timing light with me to the lake, and when it starts acting up, check to make sure all plugs are getting fire, maybe a spiratic coil?

 

[skigolfnut]

Re: Mercury 200hp Xri 1992 Idle Problem

This came from Charlie B-
I had asked him about the mixture of 50 to 1 ratio with the oil.

I am going to try the hotter plug and see what happens,


Stay with the 50 : 1 mixture and always use a quality TCW-3. Any less oil only accelerates engine wear, shortening its life. Most serious 'Hot Rodders' actually increase oil ratios. Oil is the only thing that keeps your engine alive.

Yes, you can run the BUHW.

Spark plug selection is sort of like your prop pitch, you install the one for the load/use of the motor for that trip.

Extended WOT the factory recommended may be the best application, however, extended idling and low speed, relatively light loading may require something a little different

Some of my fishing customers seldom ever open the throttle much, and I tend to install plugs to fit the owner.

Some of those boats even end up with a standard electrode plug such as the B8HS, and if there is adequate piston clearance its extended tip version the BPR8HS, gapped at .032

Reasoning is threefold,

much more electrode area, less likely to become insulated with oil and misfire

second, initiation of the flame kernal is farther into the combustion chamber, larger flame kernal, better flame progression, less chance of misfire.

third, as engine ages and compression falls, (115 or below), heat range can be increased to keep plug tips clean, less likely to foul/misfire.

 

[ElectrixBass]

Re: Mercury 200hp Xri 1992 Idle Problem

Stock Oiling system
Stock NGK BU8H plugs

This problem just started a few of weeks ago for me. I have not changed or adjusted anything on the motor. I know it's burning oil and seems OK. I've checked for leaks and cleaned the plugs with a wire brush. The plugs didn't seem too fouled and when reinstalled and run with ear muffs it seemed to run about the same. I'll have it on the water this weekend.

I'm fairly handy with tools (electrician) but certainly not a mechanic but t seems to be miss firing on a cylinder. As you increse the rpm it seems to improve. I'll try to check spark at each plug tomorrow.

It starts and idles coming off the trailer although a bit rougher than before. Once I make the first run it seems to consistantly have idle issues the rest of the day. During the week when I just check the start to make sure battery is strong, it starts and idles fine (although rough).

Thanks for your input and help

Just love the smell of 2-stroke oil in the morning.

 

[skigolfnut]

Re: Mercury 200hp Xri 1992 Idle Problem

I am going to take a timing light with me next time I go out and see if I cant narrow mine down to see if one of the coils is on the fritz, I used the timing light to figure out when the switch box would fail after it warmed up,
same principle, when it starts acting up I am going to try and see if one of the plugs are not getting spark. I am also going to try the hotter plug