Loss of power - unusual coloring of catalytic converter?

dduelin

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Ok, this is a weird one. Last Friday I'm heading 175 miles out of town on a short weekend trip on my ST1300. About 10 miles into this at 70 mph on I-10 the bike hiccups and jerks twice, maybe three times, then loses power and begins slowing down. I'm in traffic so I give it more throttle, lots more throttle to keep up. The loss of power was apparent but it held speed with more throttle and did not continue slowing down so I know the engine was continuing to run albeit with a huge loss of power. With the on and off jerking at first issue it felt like it was running out of gas or or the ignition was cutting in and out then it jerked once or twice again and ran normally again like nothing happened. The whole event was maybe 10 seconds.

I should have turned around right then and gone home but I really wanted to get to the destination on time and kept going. I thought maybe it was a bit of water in the fuel that passed through an injector or two ....About 40 miles into the trip it did this again but not as bad or as for as long. It jerked a couple of times then back to normal. Again I thought I should turn around but decided to press on and changed my route from small back roads to staying on more traveled roads so my road service could find me easier if I had to stop or broke down. I rode about 150 miles with no future appearance of the problem. The last 20 miles or so was down a long straight road through a swamp with both shoulders flooded and full of water. No place to really pull off the road and a narrow wet shoulder if you had to. I passed a sign indicating 9 miles to go and the issue reappeared. This time it did not clear for maybe a minute or so. I decided as long as the bike would run at this level of power I would ride it out. The bike slowed but kept running as if on 2 or 3 cylinders. Despite the speed of about 45-50 mph mph the exhaust smelt overly rich like raw fuel was dumping through a cylinder that wasn't firing. I had time to check a few things out. Because I've had electrical grounding problems before that stopped the fuel pump along with lights, horn, cooling fans, etc, I cycled electrical items on and off on and off with no fix-it. I down shifted and changed engine rpms with no fix-it. Dash lighting and temp remained normal. Then it hiccuped once or twice and all was normal again. I rode the last few miles to a gas station and filled the tank. I rode it 10 miles the next day and it was fine.

Yesterday I rode it home and it ran perfect for the entire 176 miles but obviously I want it diagnose and correct whatever went wrong. The right side catalytic converter has turned gold/ brown and has the appearance of running an unusual exhaust mixture or temperature. The left side one is the normal shiny polished chrome. I clean the cats and mufflers regularly so this one-sided change is very apparent. I just cleaned the pipes not too long ago so I know the change is, I believe, related. I keep them shiny chrome because I dislike the goldish brown discoloration they get.

What would cause the RH cat and muffler to change color so quickly....running overly hot exhaust gas temps from overworking because the problem loss of power was on the left side or was the right side exhaust running too rich/cool and this discolored it? On my bike the usual catalytic converter/muffler discoloration takes thousands of miles to occur.

Tonight I will pull the cowls and check the spark plugs for coloration changes. At this point intend to think I had a momentary ignition or fueling problem and the plugs and plug leads are a starting point.

I'll entertain any other thoughts.

I'll add I replaced the fuel pump about 16,000 miles ago when the bike passed 115,000 miles. It didn't have symptoms I just did it to prevent fuel pump problems.
 

Firstpeke

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Sounds like discoloured exhaust has run hotter then the other, possibly unburnt fuel going down there and igniting in the exhaust, or conversely that side was the side running properly, but running hotter as it was doing more work.....

Does sound a bit like something was cutting out on one pot or even two..... but could be hard to pin down....
 
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I would check the exhaust side with color for blockage. 2 stroke would act like that when carbon built up . Good Luck ! Joe
 

Throttlejockey

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Could be a fuel pump on it's way out. Did you replace yours yet? EDIT- just saw where you did.
 
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dduelin

dduelin

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How about the fuel filter? A dirty five way tee? Bad fuel? Keep us posted on what you find.
I can't rule out anything now but the asymmetric nature of the discoloration doesn't suggest bad fuel or filter only affecting one cylinder bank or 1 cylinder. I cleaned the Tee 16,000 miles ago and replaced the vacuum hoses. The fuel in the tank at the time was a few days old and purchased from a busy Shell station I normally buy gas at. I will post results.
 

bdalameda

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It really sounds like the fuel pump. Not the first time a low hours pump has failed. Especially suspect the pump because it appeared better after filling up the tank. Also look at the evap canister. Plugged evap canister could cause vacuum buildup in the fuel tank and seem like a bad pump.
 
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970mike

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It really sounds like the fuel pump. Not the first time a low hours pump has failed. Especially suspect the pump because it appeared better after filling up the tank. Also look at the evap canister. Plugged evap canister could cause vacuum buildup in the fuel tank and seem like a bad pump.
How do you unplug an evaporator canister? Replace it?
 

bdalameda

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How do you unplug an evaporator canister? Replace it?
You can try and flush out a plugged canister but usually they are just replaced. The higher the mileage the more suspect an evap canister becomes. If you regularly fill up your tank all the way to the very top you will be sending fuel down into the canister and this can reduce the life of the canister.
 
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I think Rrboomer might be on to something. A partially clogged catalytic converter might be the culprit. It would produce heat and the extra heat would burn some of the carbon built up in the CC and make the exhaust smell rich. The extra heat then burns a new pathway for the exhaust to exit and the problem goes away temporarily. See if the exhaust pressure seems equal while the bike is idling.
 
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dduelin

dduelin

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It really sounds like the fuel pump. Not the first time a low hours pump has failed. Especially suspect the pump because it appeared better after filling up the tank. Also look at the evap canister. Plugged evap canister could cause vacuum buildup in the fuel tank and seem like a bad pump.
I initially thought fuel pressure during the first incident but the gas tank was ~full and had maybe 15 miles on it when the issue surfaced and only took 4.1 gallons to fill shortly after it ran poorly for 1 or 2 minutes. Like I said I'm not discounting any idea but how would low fuel pressure affect EGT on one side?
 

v8-7

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A bad cat came to my mind as well as a possible ignition glitch.

If it smells like rotten eggs ( sulfur ) , check the cat . It will get progressively worse .

I have a spare set of mufflers for loan if you need them .
 
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dr1954

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Mine did something similar when the pulse wire for my cruise grounded out and I lost the left side coil. The left side pipe got extremely hot real quick. The pipe also discolored and never looked the same.

My guess is ignition related somewhere.
 
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dduelin

dduelin

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The plugs looked OK tonight but then the bike only faulted a few moments then ran about 200 miles without recurrence. I had new plugs so I put them in. The only item that stood out tonight with the coils and high tension leads was the rubber insulating boot on the black/white low voltage lead on the left coil had a tear in it. I repaired it with electrical tape and reseated it. I ran the bike about 20 minutes checking the temps of the headers and cats. The temp readings were within 10 degrees side to side.

Thanks for all the replies, I do appreciate it.
 
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What seems like an obvious question to me is, why would the FI indicator not light up. I'm thinking that if there is a FI code for any of the possible culprits that you suspect you could scratch it from the list if the FI light doesn't turn on(?).
 
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The only item that stood out tonight with the coils and high tension leads was the rubber insulating boot on the black/white low voltage lead on the left coil had a tear in it. I repaired it with electrical tape and reseated it. I ran the bike about 20 minutes checking the temps of the headers and cats. The temp readings were within 10 degrees side to side.
Not having a 1300, but have to ask if this coil repair controlled the ignition on the side with the discolored cat ? I'd lean toward ignition intermittent. JMHO
 

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Mine did something similar when the pulse wire for my cruise grounded out and I lost the left side coil. The left side pipe got extremely hot real quick. The pipe also discolored and never looked the same.

My guess is ignition related somewhere.
My thought is the coil also... one coil fires both 1 & 3, the other fires 2& 4
The plugs looked OK tonight but then the bike only faulted a few moments then ran about 200 miles without recurrence. I had new plugs so I put them in. The only item that stood out tonight with the coils and high tension leads was the rubber insulating boot on the black/white low voltage lead on the left coil had a tear in it. I repaired it with electrical tape and reseated it. I ran the bike about 20 minutes checking the temps of the headers and cats. The temp readings were within 10 degrees side to side.

Thanks for all the replies, I do appreciate it.
This is your problem. Happened to me about a year and a half ago. I replaced the coil on the side where the pipe turned blue only because I had two spares that I had lying around. I'm 99% sure though that the problem was really due to an intermittent low voltage connection at the coil, i.e., loose spade connection on one of the two wires. If you were to look at your fuel consumption during the time that the misfiring is occurring you would see that your mpg figure drops almost in half...
 
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Byron

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I'd check all the ground wire locations, starting with any that were coil related.
 
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