Slight stumble (throttle)

[Canadian FJR]

My 2003 has a slight stumble/hesitation around 1500-2000 RPM when in first gear feathering the clutch from a stop.

Idles perfect, runs smooth and acceleration is better than my 2018. Any suggestions? I have run some Ring Free through it. Maybe just in need of a throttle body sync?



Canadian FJR

[FJRoss]

Throttle position sensor, maybe?

[Canadian FJR]

Possibly, I’ll check that tomorrow



Canadian FJR

[raYzerman]

Well, if you wouldn't ride the freakin' thing like grandma all the time, you wouldn't have half these problems, jeez......... just kidding, I don't think you're even capable of riding like grandma.....

Could be a number of things..... what's the mileage on the old girl anyway?

Throttle body sync won't be much different than the last time you did it, would take a change in valve clearances to alter it. Even then, I don't think it the cause, but EZ enough to tweak it back, costs nothing. When's the next valve check due? Now would be the time you'd like to know what the clearances were on the last check.....

Just reflecting back on some Gen1 issues I've worked on this past year.....
To eliminate any water being a contributor, put two ounces of isopropanol in the tank in addition to the RingFree (Seafoam has 30% isopropanol, RingFree I don't think has any). RingFree should be a good injector cleaner, but takes time to work.

How old the spark plugs (mileage). Could be a coil problem, they'll test OK but save this for later. How about taking the spark plug boots off, trim 1/4" off the spark plug wires, spread the strands and push/screw them back on... but wait, check the resistance of the boots while they're off... inside there's a resistor and the connection may be oxidized.... unscrew, clean, reassemble, check resistance after cleaning... should be 10k ohms. If wildly off, it is a potential problem.

TPS.... never can properly diagnose these.... cheap to try adjusting it to get off a worn spot at zero throttle and a bit above where the throttle spends most of its time.... go into Diag, see what the low end reading is, should be around 12-14-ish... rotate it so it's up a few points to say 18-20. You can check to see how differently it idles at 18 vs. 14 if you want to play and go back into DiAG again. IF you had a spare (2003-2012 the same part) you could play with......?? If it's big miles and never replaced, well, maybe it's time....

[Canadian FJR]

Thanks Ray, I’ll check my records tomorrow and will know better the last time valves were checked and plugs changed. There’s only 280,000 kms on it.

I’m thinking the TPS may have been changed way back when due to a recall but I’ll confirm my notes tomorrow.


Canadian FJR

[Canadian FJR]

Just went through the archives;

Original TPS was replaced May 2007 - 75,258 kms

Valve check, TB Sync and plugs were done in 2017 - 251,000 km.

Currently at 280,000 km

Checked the Diag screen this morning
Shows 17-100 and no skipped numbers as the throttle is opened.

This bike went to a new home from 2018 until this past year but he only put 7,000 kms on it during that time.

I’m leaning towards new plugs and clean up the plug wires at this point.

I’m fine with replacing the TPS also just to eliminate that 100%.

Canadian FJR

[FJRoss]

Might not hurt to have the fuel injectors serviced. Have you checked the condition of the big white connector under the tank?

[Canadian FJR]

Fresh set of plugs NGK CR8Es and and a slight bump with the idle and the works seems to be good again.

Thanks for the input folks.


Canadian FJR