Running Rich

[ozy2448]

I have a 2004 Yamaha FZ6 with 7,700 mile on it. In the last two weeks it has been running rich (2 others feel the same way) At 30-40 MPH in 3rd gear when cracking the throttle it sputters usually once and then jerks to full "response". At highway speed when downshifting or just accelerating it feels like its running at about 80% power. I can smell the extra fuel when driving. On down shifts the "rap rap" sound has increased dramatically, no flames though. Any feedback would be great. Thanks

 

[CHEMIKER]

Do you have aftermarket exhaust? With or without baffles?

 

[TownsendsFJR1300]

I would try a full throttle run and immediatly turn off the bike. Let it cool down then remove the spark plugs and inspect. It should indicate what cylinders are running rich.

You may have an injector with crap stuck in it leaving it open allowing extra fuel to flow.

You can get your injectors cleaned and tested for a lot less than a new injector...

Hopefully the ECU isn't toast sending bad signals to the FI system...

Good luck.

 

[Shamus McFeeley]

I would try a full throttle run and immediatly turn off the bike. Let it cool down then remove the spark plugs and inspect. It should indicate what cylinders are running rich.

You may have an injector with crap stuck in it leaving it open allowing extra fuel to flow.

You can get your injectors cleaned and tested for a lot less than a new injector...

Hopefully the ECU isn't toast sending bad signals to the FI system...

Good luck.

In addition to this, don't forget to test your T1 (intake air) sensor. Its an easy test, and will save you from chasing your tail. Are you getting a CEL?

 

[CHEMIKER]

Before you do all that stuff, let us know if you have aftermarket exhaust. Mine did exactly what you describe when I installed 2bros exhaust with no baffles. Gas smell, popping, delayed response on throttle roll-on...

 

[ozy2448]

I have scorpion slip on exhaust.

 

[ozy2448]

It was running perfect one day and started this the next. Nothing changed didn't run different gas or anything. there are no warning lights on and no codes being shown.

 

[TownsendsFJR1300]

Something to check, if one of your spark plugs is not firing (for what ever reason) it'll obviously misfire and smell of fuel (as the gas is not being burnt) but just pushed out the exhaust.

If you can borrow or have a thermal gauge, point it at each header and check the temps at various RPM's on each cylinder...

 

[novaks47]

I have the same exhaust. With or without baffles, you will get some decel popping. If anything, it's probably running a touch lean.

However, since your problem came out of nowhere, don't rule out bad gas! Even if you always go to the same station, and use the same pump, you can get some crappy gas. I *just* had a similar thing happen to me. I filled up, and the bike ran a little rough, felt like it was down on power, and backfired a bit more than usual. Once I burned off all that fuel, and got some fresh gas in, presto, problem solved.

My advice : Check over the bike for the easy stuff, mainly maintenance things.

1. Check your plugs, as maybe one them just bit the dust. Unlikely at 7K miles, but it's worth a peek. Make sure the plug wires are fitting snugly as well. Good time to test them to make sure they're delivering spark too!

2. Check your air filter. I've got 9500 miles on mine, and the air filter is getting replaced today.

3. Burn off that gas! Run it until it's good and low, then fill up, and see if the problem persists.

4. Go ahead and run some fuel injector cleaner. Just get whatever's cheapest, just make sure it's for fuel injectors, not carbs. Pour it into the tank once you get some fresh gas in, and ride!

5. Check the TPS sensor. There's a guide on the forum on how to do it. If the TPS is bad, it can cause the FZ to run bad.

That should get you going in the right direction. Do the easy, obvious stuff first, then progress to the harder stuff if necessary. :thumbup:

 

[FIZZER6]

I have the same exhaust. With or without baffles, you will get some decel popping. If anything, it's probably running a touch lean.

I also have the Scorpion SS pipes...I did not remove the Catalytic converter...stock fuel mapping, bike has always ran just fine (45-55 mpg). I rarely get decel popping around 6-7Krpms especially in gears 2-4 when the weather is cooler.

 

[Bates121]

Before you do all that stuff, let us know if you have aftermarket exhaust. Mine did exactly what you describe when I installed 2bros exhaust with no baffles. Gas smell, popping, delayed response on throttle roll-on...

My Two Bros has been doing this as well what did you do to fix it?

 

[CHEMIKER]

My Two Bros has been doing this as well what did you do to fix it?

I put in the P1X power tips. I'm assuming the additional back pressure is what really made the difference.

 

[Bates121]

cool thanks for the tip I have them i just havn't put them in yet.

 

[DefyInertia]

throttle position sensor changed out under recall for this low mileage 2004?

 

[Motogiro]

I'll 3rd checking the TPS

 

[FinalImpact]

Something to check, if one of your spark plugs is not firing (for what ever reason) it'll obviously misfire and smell of fuel (as the gas is not being burnt) but just pushed out the exhaust.

If you can borrow or have a thermal gauge, point it at each header and check the temps at various RPM's on each cylinder...

A squirt bottle works well also. . . Aim at the header / flange area. . . if you have dead hole it won't flash off as quickly.

I'd bet the TPS has a bad zone. That'd be my fist step. How long have the pipes been on it?

 

[Motogiro]

Though this may be a long shot. The kill switch allows 12+ vdc from the main switch to got to the ignition coils primary windings. When the ECU sees voltage coming out of the primary winding it sets the logic to cycle and do the self test and run the fuel pump etc. A faulty kill switch may allow voltage to trigger logic but be to high a resistance to pass current to the coils. Maybe jump the kill switch so that you know you have full current to the coils and take it for a test ride.

Don't discount disconnecting the battery for a few minutes to dump volatile memory. It may have learned a stupid trick from an anomaly.

 

[novaks47]

I also have the Scorpion SS pipes...I did not remove the Catalytic converter...stock fuel mapping, bike has always ran just fine (45-55 mpg). I rarely get decel popping around 6-7Krpms especially in gears 2-4 when the weather is cooler.

Yep, same here, cat still there. I did do the CO mod, and richened it a bit, and after some fiddling, I've got better throttle response, and minimal popping. Excellent gas mileage. I can make it pop if I cruise at over 6K for a bit, then roll off the throttle, then right at 5K it'll pop a bit, then settle down. Very minor though, sometimes hard to even hear it. Before richening the bike, it was louder, and very consistent. Now I have to "prime" the exhaust to make it happen. LOL

Syncing the throttle bodies can hep a lot too! Mine were a ways off, back when the FZ only had 6K on it. If one is way out of sync, that could cause issues as well. That was back when I had the Two Bros exhaust, and the amount of backfiring was cut in half after the sync. So there's something else to consider.

Oh, and the ECU reset that Motogiro mentioned!! Duh! Can't believe I forgot that one. LOL That's nice and easy one to try.

 

[ozy2448]

The pipes were on it when I got it and there was never a problem before other than the popping. Now that I think about it this did start after my last fill up, so I am almost on E, going to run it down and do the injector cleaner and use a different gas station. I am also going to check (maybe change) the plugs after inspection. I will be calling Yamaha to see if the recall was ever performed. Just wanted to say thanks for all the feedback from everyone, it is nice having a resource like this forum where everyone has the same bike and in most cases the same issues to bounce all this information around. :wav: