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Discussion Starter · #1 ·
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).
 

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Thanks for this insight. I'm not having any problems right now on my 02 but this is easily done preventative maintenance.

Sent from my SM-N960U using Tapatalk
 
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It's great to have members posting the cures to their problems.
A lot of faults or problems get posted, other members come back with things to check,
but the starter of the thread dosn't always come back with what cured the fault.
 

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Did you buy the lines from Honda or can I just buy some rubber hosing from somewhere?

Also is there a way to test an Oxygen sensor? I have original headers but Delkevic pipes. My surging has recurred a bit worse after playing with my AIT Regulator box (Memjet Evo Prime).

I'd also keep the bike longer if it was smooth. Hopefully can sort out any issues.
 

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Discussion Starter · #5 ·
Did you buy the lines from Honda or can I just buy some rubber hosing from somewhere?

Also is there a way to test an Oxygen sensor? I have original headers but Delkevic pipes. My surging has recurred a bit worse after playing with my AIT Regulator box (Memjet Evo Prime).

I'd also keep the bike longer if it was smooth. Hopefully can sort out any issues.
I made the lines from some standard vacuum tubing. It has a 3.5mm inner diameter, but 5mm & 3.2 mm was all I could find locally so I got it from Ebay.

You can disconnect the o2 sensor to see if things smooth out. The system will enter an open mode (similar to cold start) and dump more fuel in, but it should give a clue. The 02 sensor has 4 pins, two for a built in heater and two where the sensor outputs 0 to 5v for the signal. It would be hard to test the signal without an oscilloscope, but a multimeter would show it the sensor completely failed. Disconnecting it will make the FI light come on.

There's also the throttle position sensor near the fuel pressure regulator; it's just a resistor, so it's easy to test as you open the throttle.

Then there's the MAP sensor and IAT on the airbox, both with 5v signaling.
 

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Part number for davidsilvers, you get 1 meter, its enough to replace all vacuum lines on throttle bodys, I just took them off one by one, cut to same length and repeat.
You will need a another meter to replace tank breather as well.... £11.51 GBP a meter.,, part number is, 95005-350-0120M
 

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Cheers I bought some from a place called JC Motor or something on ebay. Its quite hard and stiff, 3.5mm ID. I got 5 feet of the stuff. Let's see! Will change on weekend.
How did you get on with this? I've been contemplating replacing hoses for the heck of it, seeing as it's winter and bored, haha!
 
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