Help, light load missing

[1hotbusa]

HI there,

I did read the light load surge thread on the forum, but the op was not specific in what the bike was doing and when it was doing it.

I have an issue with what seems to be a slight missing at steady throttle at ~3000 - 3500rpm. This occurs at a steady throttle at a steady speed usually in 6th gear but have had it in other gears.

When this problem occurred I suspected the fuel pump. I pulled the pump and replaced the internal filter (2000 model), which had punched one end out. I also cleaned the wire gauze.

I have contact cleaned the fuse and relay in case it was intermittently cutting the fuel pump out with prolonged operation.

When the problem occurs, a twist of the throttle or changing down a gear makes it go away.

Can anybody help.

[Maj]

How long since you changed sparkplugs Graham, also if the filter was compromised follow the system thru and clean all , i'm not that familiar with the external pump models but i seem to recall Rev or Giddy talking about 4 filters and thats not the 4 individual injector screens

[1hotbusa]

How long since you changed sparkplugs Graham, also if the filter was compromised follow the system thru and clean all , i'm not that familiar with the external pump models but i seem to recall Rev or Giddy talking about 4 filters and thats not the 4 individual injector screens

Hi Greg
The spark plugs were replaced about a year ago. I have looked in the manual and I have only found 1 fuel filter, which is in the pump on the 99-00 model. Can anybody shed any light on where the rest of these filters may be.

BTW it was the end cap of the filter that died, not the filter material, however I agree that it was possible that the filter contaminated the fuel feed.

It also seems strange that it is precise on when it decides to miss, ie ~3000rpm. I might throw some fuel injector cleaner through it to see if that makes a difference.

[BUSGO]

I suggest you check the regulator connections Graham. They have been know to melt away on the early models and this causes specific electrical problems.
Yes there is only 1 filter on the external pump models but there are several screens as well.
I don't think that is your problem though.
The tip over sensor and regulator are linked in some way to the Fuel pump relay.
Maybe start there.

[1hotbusa]

Hi there,

I had the reg rec plug melt down on me last year, I managed to repair that. I will have to check the tip over sensor.

Would these symtoms explain why it happens at a set rev range, if either of these items failed it would be across all rpm ranges wouldnt it?

[andcad]

Hi there,

I had the reg rec plug melt down on me last year, I managed to repair that. I will have to check the tip over sensor.

Would these symtoms explain why it happens at a set rev range, if either of these items failed it would be across all rpm ranges wouldnt it?

If all else fails cut the PINK wire comming from the Gear Position Switch (GPS)

[BUSGO]

Graham, in addition to what Andy has just suggested, if the bike is revving out with no loss of power above the trouble zone, I doubt that it is anything to do with the fuel filters.
However, the fuel regulator is normally protected by a dirt screen and that may be blocked causing the fuel pressure to drop at certain revs.
Rev advised to remove this screen from all the external pump models many years ago as a precaution. The vacuum hoses servicing the fuel system and regulator may also be leaking very slightly or even be pinched somewhere around the tank. I found this problem once when I had my 99 bike.