06 Apex runs rich

[highboy77]

My 06 Apex runs rich on a cold start up. Starts right away but then starts to load but will continue to run. Once warm it seems to run fine. The only other symptoms that i have noticed is a drop of 1-2 mpg and it will give a subtle backfire on decel after a long hard run. I have replaced the spark plugs because it was time anyway and the complete exhaust system is fine. Also went into the diagnostic mode and all values were good. Checked all of the sensors individually with a DVOM and all seemed to be good. I am getting a fuel gauge tomorrow to check fuel pressure, but beyond that I am stumped. Anyone have a similar problem? Any ideas? I read on this forum about adjusting the idle fuel mix but I think it is rich across the whole rpm range due to the mpg and backfire.

 

[APEX 06]

How did your plugs look, with what its doing sounds alot like bad donuts/cracked y pipe.

 

[highboy77]

Plugs are black. Loaded up really bad on my initial start for the season. Just cleaned them but can't ride it to clean it out due to lack of snow. Going to Michigan this coming weekend. The exhaust is good. I do a very thorough summerization which includes looking at the exhaust donuts and pipes. All good.

 

[APEX 06]

Seaform it, see if it cleans it up.

 

[highboy77]

I will give that a try this weekend. Do you dump the whole can in a full tank of fuel?

 

[APEX 06]

I do with a full tank.

 

[highboy77]

Thanks! I will let you know in a week.

 

[Maurizio Benelli]

I think my 06 Apex runs rich too. When I press the throttle fast it sometimes even shuts down. It smokes like hell and I´ve never been able to run over 124 miles with full gas tank.
Even when driving on steady throttle on trails. When the engine warms up it doesn´t shut down anymore with fast throttling, but it hesitates for a second or so.

I´ve just changed the donuts and y-pipes. Plugs start their 4th winter now, could they cause this kind of problems?

 

[whits-end]

Highboy77

Mine does the same on a cold start. At home it's kept in a heated garage so it starts and runs fine. If I'm away and it's been outside all night it acts a little funky. Fires up OK but after a short time it runs rich and sputters. Then after it warms a bit it clears up again. Runs fine after that. I assumed it was a sensor or connection somewhere, but I never dug into it because it wasn't a big problem.

I doubt your backfire on decel is connected. Sounds like a donut issue.

 

[highboy77]

I found a cracked flare end on the RH exhaust pipe. The donuts were just replaced about 1500 miles ago. The donuts were still good so I replaced only the pipe. Seems to run better but still kinda loads after about 10 seconds into a cold start and then it will eventually clear some. My other 06 Apex does not do this. I was checking vacuum at the fuel pressure regulator and could only get about 7 inches which seems very low which causes the fuel pressure to go high. I cleaned the hoses and the throttle body ports with no improvement. I would think that there should be more than 7 inches and the high fuel pressure may be the issue. Haven't had time to check my other Apex.