Joined
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81 Posts
I've had fuelling issues for a couple of years (2003 bird). Multiple issues which I resolved over time, and each time I thought it was like a new bike, but never as good as my old 99 bird.
First issue was a failing o2 sensor causing surging, so I bypassed it and fit a power commander. A great improvement.
Manual tuning never got me where I wanted to be, so eventually I replaced the fuel pressure regulator. It wasn't leaking, but I think it was not moving smoothly giving some uneven running. Replacing it improved things a lot, and I could finally tune the bike by ear half decently.
Fuel economy improved, 42 mpg on the motorway, but the bike seemed to intermittently run a bit worse. It seemed like it was a bit raspy, making me miss the smoothness of the 99. Additionally fuel economy was terrible around town; at low revs, taking it very easy, I would see 25 mpg.
I finally replaced all the vacuum lines to the MAP sensor. It's the 5 way connector with a line to each cylinder and one to the MAP sensor.
The lines didn't have any major splits, but I could see cracks at either end in some, once I had removed them.
The difference is huge; the bike is now super smooth and I've changed my mind about potentially looking for something else.
I'm kicking myself it took so long; I had tested the voltage on the MAP sensor and it looked ok. It seemed to respond to airflow changes - but the voltages were very different after I fit the new vacuum lines (very being about -0.4V at idle).
First issue was a failing o2 sensor causing surging, so I bypassed it and fit a power commander. A great improvement.
Manual tuning never got me where I wanted to be, so eventually I replaced the fuel pressure regulator. It wasn't leaking, but I think it was not moving smoothly giving some uneven running. Replacing it improved things a lot, and I could finally tune the bike by ear half decently.
Fuel economy improved, 42 mpg on the motorway, but the bike seemed to intermittently run a bit worse. It seemed like it was a bit raspy, making me miss the smoothness of the 99. Additionally fuel economy was terrible around town; at low revs, taking it very easy, I would see 25 mpg.
I finally replaced all the vacuum lines to the MAP sensor. It's the 5 way connector with a line to each cylinder and one to the MAP sensor.
The lines didn't have any major splits, but I could see cracks at either end in some, once I had removed them.
The difference is huge; the bike is now super smooth and I've changed my mind about potentially looking for something else.
I'm kicking myself it took so long; I had tested the voltage on the MAP sensor and it looked ok. It seemed to respond to airflow changes - but the voltages were very different after I fit the new vacuum lines (very being about -0.4V at idle).