01 1150GS Never Runs the same??

[mickeymc]

There is a similar thread about an RT that never starts the same and maybe the same type issue. Here are some of the particulars. The GS has 110,000 miles. Just rode it to Sedalia and home 3000+ miles. Recent valve adjust, oil change, etc. Mostly interstate travel on the way out. Noticed bad vibration at 3800-4000 (and higher) rpm. Any gear. After gas stop engine ran smooth at same RPM's. Ok so it was the gas I thought, but, stopped for lunch, no gas, back to the vibrations. Same scenario for rest of trip, sometime vibration, sometimes smooth. Once on the trip on startup I heard a louder than usual "knock" and after that rough running. Is it wore out and time to retire the GS?

 

[biometrics]

Sometimes smooth running and other times not. That is not worn out... that is an intermittant problem and the first thing that comes to my mind is the HES. Have you ever had it replaced?

[Galactic Greyhound]

Got a cat fitted?

Might be a dodgy O2 sensor - disconnect it and see how the bike runs.

 

Intermittent lower fuel pressure due to ageing/leaking fuel pump hosing?

Simple test may be to check the return hose fuel flow but a better test would be to measure the fuel pressure from the pump to the pressure regulator - should be around 43 psi according to recent thread here by roger 04 rt.

[mickeymc]

While I was at the rally I heard someone talk about a failed HES. Never thought about one being intermittent, I thought the wires were what mostly sent bad but worth a check. Never been replaced.

 

[dirtrider]

Afternoon Ced

 

Having fuel pressure without enough flow is pretty meaningless when it comes to runability problems. To run properly the system needs ENOUGH pressure at a FLOW great enough to operate the engine.

 

The fuel return line test shows return fuel flow at maintained pressure. That means the pump MUST be making enough pressure to open the regulator (around 43 psi) SO, the amount that is returning is the fuel available at that 43 psi.

 

If only 1 once is returning every minute then that is way low on volume to run the engine under load but since there is "some" return flow it must be maintaining the 43 psi. On the other hand if 1 gallon is returning every minute that is 1 gallon flow at 43 psi (a very good thing).

 

[Galactic Greyhound]

Thanks Dirtrider - I'll remember that; Pressure AND Flow!

 

I'm learning a lot on this forum.