by pabarlow » Tue May 25, 2021 10:20 pm
Hello friends, I have a 2017 CRF250L rally with 20,000 miles on it. It will not idle or run below 2000 RPM. I've attempted a lot of diagnostics and part replacements but can't identify the issue. Looking for suggestions before I finally give up. Thanks in advance.
The bike always starts instantly when cold, and correctly runs above 2000 RPM by itself briefly while it warms up. But as soon as conditions start sending the bike below 2,000 RPM towards its normal target warm idle, it quits. If held at higher RPM by throttle it will happily continue running, and can actually be ridden nicely indefinitely if you never try to idle.
When I bought it it had the full FMF exhaust, EJK fuel controller, and a modified air box. This issue existed then, too. I have since installed a stock pipe and stock tail pipe / Muffler, and sealed up the air box lid.
In trying to diagnose this issue, I have replaced the spark plug, air filter, fuel filter, fuel line, O2 sensor, the entire throttle body (complete with never-touched TPS amd IACV, and fuel injector) (and reset the TPS), checked valve clearances and valve timing, bypassed the fuel evap system (to avoid any vacuum leak at manifold), and tried plugging the exhaust port air injection system (though this should not affect idle).
While it feels like a fuel issue, I don't understand why it works fine at speed, and I've replaced the whole throttle body,
While it feels like a fuel issue, I have tried disconnecting the tip-over sensoR. ALSO, I feel like the coolant temperature sensor is working right as the bike knows when it is doing a cold start, and correctly triggers the fan when hot.
I haven't yet done a compression test, but again the valve clearances are good and the bike seems to make fine power.
Any suggestions? I am at my wits end.
Cheers,
Peter