Running on three cyclinders

Yamaha FJR Motorcycle Forum

Help Support Yamaha FJR Motorcycle Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

AStar

Well-known member
Joined
Jun 26, 2007
Messages
95
Reaction score
0
Location
Uvalde, TX
My 07 with 5500 miles has been a little ill lately. It has for sometime started in the moring with some missing sounds like one of the cyclinders fails to fire once in a while. It normally clears up after it gets warm. Well today when I started it again it was missing only this time it was missing on every motor revalution. After the engine was warm it continued to run missing on one cyclinder. I could also smell a little gas I believe was coming from the tail pipe. It got a little better and I took it down the street, it seemed to clear up at higher rpm but when in lower rpm range it seemed like it might be missing some. My first thought was the fuel injectors were dirty then I began to think that one of the spark plugs may have fouled.

Any thoughts before I get the stealer involved.

 
Fuel, air, and spark. The last is the most common problem by the way.

Air doesn't sound like an issue or it would usually affect more than one cylinder. Unless it's a fundamental compression issue.

Sounds like you're getting fuel if you're smelling it. An inefficient injector is likely going to be more rough running and unless cylinder walls are being washed down you probably wouldn't smell unburned fuel once up to temperature.

Spark. Could be the plug, the plug boot, the plug wire, the coil. How many miles since you last changed the plugs. If 8,000 or more and the stock plugs this is where I'd begin as they should be replaced anyway. Fairly easy job and great opportunity to upgrade to Iridiums.

 
Fuel, air, and spark. The last is the most common problem by the way.
Air doesn't sound like an issue or it would usually affect more than one cylinder. Unless it's a fundamental compression issue.

Sounds like you're getting fuel if you're smelling it. An inefficient injector is likely going to be more rough running and unless cylinder walls are being washed down you probably wouldn't smell unburned fuel once up to temperature.

Spark. Could be the plug, the plug boot, the plug wire, the coil. How many miles since you last changed the plugs. If 8,000 or more and the stock plugs this is where I'd begin as they should be replaced anyway. Fairly easy job and great opportunity to upgrade to Iridiums.
5500 total miles, no spark plug changes yet.

I will check the spark plug wires to see that they are set properly.

Thanks.

 
Start with the plugs, you will be able to read the plugs for color and know what one it is. I've only had a couple of plugs go bad in 37 years of riding but one of those was two days old.

 
It's often been said here by a few that the plugs last forever. Couldn't possibly be the problem. Could it? ;)

 
All four plugs look about the same. But now that they are out, I guess I will put new ones in. I hope that it is not something like the boxes that send the spark to the plugs.

 
All four plugs look about the same. But now that they are out, I guess I will put new ones in. I hope that it is not something like the boxes that send the spark to the plugs.
Just keep troubleshooting one step at a time.

Unless, of course, you're impatient like me.

Then do a bunch of work and when the problems fixed you never really know what was wrong.

But by then, who cares? :rolleyes:

 
If you have a power commander, it may be going bad too. The way to check is to just disconnect it and reconnect the O2 sensor. Another forum member had that problem recently.

 
No power commander. I have to wait until tomorrow for the new plugs. I have done the Barbarian Jump thing. But that was about a year ago with not problems.

 
While you are buying spark plugs buy fresh oil and an oil filter because you almost certainly have fuel in your oil.

Quickest way to identify which cylinder is to put the plugs in and start the bike and see which exhaust header isn't heating.

If your plugs are good and you're smelling fuel, There are only two coils, so it won't be a coil though it ould be the cable or the cap.

 
I have the new plugs in the bike and it seems to run better but it still misses at start up until the motor gets to two bars on the temp scale.

 
I'm the one that the PC when out on. It just needed a reboot and software reload.

While troubleshooting, I bought a set of coils off Ebay for $65.

I figured it was cheaper to just buy them and try it, than to pay the shop to troubleshoot for me.

I ended up getting it solved before the coils arrived. I never even mounted them.

If you decide you want to try swapping out the coils, or if you trace it to the ignition coils,

I'll sell mine to you for cost + shipping.

Just send me a PM.

PS - The ignition wires are part of the coils. To replace wires, you have to replace the coils as a set.

 
Last edited by a moderator:
I will check for a vaccum leak then move onto the coils. Thanks for the help and I will keep updating.

 
Well, I took the bike to the stealer for service and they found nothing wrong with it, other than telling me that it just does not run write. The only thing they could offer was to start replacing parts with new ones until they find out which one is bad. They said that it tested good. They did loan me a cpu to try at home, which I did and it did not change anything. I think I will try the coils next and see if that helps. The Yamaha tech told the dealer that they thought it might be a sticky valve. That might be the next thing to look at.

 
Well, I took the bike to the stealer for service and they found nothing wrong with it, other than telling me that it just does not run write. The only thing they could offer was to start replacing parts with new ones until they find out which one is bad. They said that it tested good. They did loan me a cpu to try at home, which I did and it did not change anything. I think I will try the coils next and see if that helps. The Yamaha tech told the dealer that they thought it might be a sticky valve. That might be the next thing to look at.
In the future, if ya want service, run - don't walk, to a different bike shop

Just my 1.5 cents

 
All four plugs look about the same. But now that they are out, I guess I will put new ones in. I hope that it is not something like the boxes that send the spark to the plugs.
This makes me think one of the sensors that supplies the ECU isn't doing its job. I'm thinking coolant temp sensor (tells the ECU that the bike is cold and to adjust fuel delivery accordingly) or O2 sensor, which can be a complete wildcard for symptoms.

I don't know where the temp sensor on the FJR is elevation-wise, but on my car it's almost at the top of the cooling system, so if the water level drops by a little bit, she runs like hammered crap. So I'd check the coolant level. The REAL level, not the overflow tank.

 
All four plugs look about the same. But now that they are out, I guess I will put new ones in. I hope that it is not something like the boxes that send the spark to the plugs.
This makes me think one of the sensors that supplies the ECU isn't doing its job. I'm thinking coolant temp sensor (tells the ECU that the bike is cold and to adjust fuel delivery accordingly) or O2 sensor, which can be a complete wildcard for symptoms.

I don't know where the temp sensor on the FJR is elevation-wise, but on my car it's almost at the top of the cooling system, so if the water level drops by a little bit, she runs like hammered crap. So I'd check the coolant level. The REAL level, not the overflow tank.
Good tip, I will check that after work. Thanks

 
Top