X720SE starting issue

250exc · Jun 17, 2016

"POPS" or backfires through the intake on first start of the day sporadically, any ambient temp., 570 hrs., valves have been adjusted 3x's, 91 octane ethanol free gas, spark plugs replaced every 200 hours, air filter clean, fuel filter been replaced. Just curious if anyone has experienced this concern with there Kawasaki FD750D EFI engine?
Thanks

Richard001 · Jun 20, 2016

Don't know about the EFI engine, but typically when the engine backfires thru the intake, it means that the fuel mixture is lean.

This thought also is reinforced by your comment that it only happens when the engine is cold.

Richard

Kish318420 · Jun 21, 2016

Have you check the intake manifold bolts for proper torq?

250exc · Jun 21, 2016

I agree on the lean and yes I have checked the intake bolts for torq. I even sprayed carb cleaner to see if it would suck in while spraying around the intake. Tonight I checked the air sensor, cylinder temp sensor and the pressure sensor. All are operating within parameters according to temp. and/or pressure/vac. Maybe I am using the wrong starting procedure, any suggestions??????

beenthere · Jun 21, 2016

Turn key on and wait for the pump to stop pumping, then switch to "start".. If you wait for pump, should be correct procedure.

250exc · Jun 23, 2016

I have cycled the key to allow fuel pump to run, tried no throttle, half throttle, 3/4 throttle, still does it. The other night I checked the resistance of the air sensor, cyl. temp sensor and the pressure sensor. All are operating w/in parameters according to temp., pressure and/or vac. My next step is to clean and apply di-electric grease to all harness connectors, grounds etc.

250exc · Jun 24, 2016

Tonight I checked the fuel pressure = 25PSI = OK. Will see how it starts in the AM.

250exc · Jun 25, 2016

Started OK this AM @ 3/4 throttle. Last night while I was checking fuel pressure, I removed the fuel pressure regulator and blew through it with compressed air!!!!!!!!!!

Kish318420 · Jun 25, 2016

Have you added seafoam or injector cleaner since this is EFI? It might take a couple of tanks for it to do the cleaning. If it then continues, ask the dealer if there is a way to check the control unit (computer test port to see what the software/firmware are doing)