Hi everyone,
I’m having a very specific and frustrating issue with my 2009 Kawasaki KLX250S and I could use some insight.
If I accidentally stall the bike under load (clutch stall accidentally at a trafiic light), and try to restart it immediately, it refuses to fire up.
Here are the exact symptoms:

• The starter motor cranks completely fine and fast. It does not sound weak or bogged down at all, but the engine just won't fire.
• This lockout lasts for about 10 seconds. If I just sit there and wait it out for 10 seconds, it will then fire up quite ok.
• It is NOT a hot-start issue: If I shut the bike down normally using the key or the kill-switch—no matter how hot the engine is—it restarts instantly. This happens exclusively after an abrupt clutch stall.
• Turning the key OFF and back ON to prime the fuel pump during this 10-second window does not bypass the issue; it still requires the full wait time.
• Full open thottle does not work either.

Since it cranks perfectly and starts fine under normal conditions, I’m ruling out the battery(new lithium), spark plug(new iridium), or CPS (Crankshaft Position Sensor). It feels like a temporary electronic lockout or ECU reset caused by the sudden shock of the stall.
Has anyone experienced this on a fuel-injected KLX or similar dual-sport?
Any help to fix this would be highly appreciated. Thanks!
PS. i have this issue from day 1(bought it used before 10 years or so)

 

After some search i end up suspect the vehicle-down sensor. Thinking maybe to eliminate it but it needs the correct resistor that i have no clue how to find it!

 

Often times when the bike stalls the cylinder may still be full of exhaust and requires some time for it to "air out". I had that trouble with my SR500 if I stalled, but with it I could hold the manual compression release and kick it through several times to clear the cylinder.

I don't know if it will work, but you could turn the throttle full open, not pumping, but wide open, and crank the bike a few times to try to clear the cylinder. Then try the normal starting procedure again.

 

I should ask if your bike cranks over a lot to get started when cold. If so, and it is a carbureted bike the jetting is lean You can use a Dyno Jet kit or do Kawasaki parts (what my brother and I did) to get the right jetting. Here is a web site with the information

 

Yes, tried that already with no any result. I have some updates with the vehicle down sensor actually. In first place the sensor was loose on the bracket(so maybe that could potential be the problem), then i canceled it tottally anyway to see if it makes any difference and it actually did. Tried to replicate the stall multiple times and it did work, though im not 100% sure because the bike was cold, and most of the times the issue happened the bike was hot. I need to replicate again when the bike is warm, ill do that soon.

 

Not really, it fires super fast and its an EFI.