Rode bike to bar. After an hour or so, started bike & left & within one minute engine starting popping, sputtering, & backfiring thru throttle body. Barely made it home.
Things done so far.
1. Drained all gasoline & refilled fuel tank completely. Still running like crap.
2. Replaced spark plugs & gapped to 0.040”
3. Confirmed good stator AC voltage output & well over 13VDC charging
4. Even tried a good battery from another bike just to rule out possibility
5. Replaced positive & negative battery cables. Cleaned chassis ground & replaced 10ga wire from battery to frame.
6. Replaced engine temp sensor on backside of front cylinder
7. Replaced Crank Position sensor
Plugs are getting black & sooty looking but haven’t fouled. If I take leak, wouldn’t plugs be much more whiter?
What next? I may spray carb cleaner all around intake to check for leaks but seeming how issue happened so quick, I tend not to think intake leak.
OH, haven’t got a single engine DTC. I’ve checked several times using trip reset button method. No codes.
HELP, please. Thanks

 

Do you have a tuner?

 

Did someone mess with it? Make sure the connections for the map on the throttle body looks OK.

 

No I don’t. Stock ECM.

 

Put away the parts shotgun and diagnose it. At the very least do a fuel pressure test and a compression test. Check for breaks at the injector wires.

 

Like ed said, check the fuel pressure.
M

 

Whats the best way to check fuel pressure without having to use special test tooling?
Was thinking about connecting pressure gauge to nipple out bottom of tank. Isn’t there a quick disconnect type fitting there?

 

No one has worked on bike in a long time. This issue started suddenly. I’ve got the air cleaner & backplate removed. The wiring to injectors, intake air temp sensor, map sensor, & idle/air control valve look good. I was thinking about removing the IAC valve & cleaning/inspecting. Something about a possible needle sticking.

 

UPDATE: Ran engine, mostly at idle at first, and sprayed almost an entire can of carb cleaner all around intake, throttle body, MAP sensor, injectors,.... everywhere & motor actually started running better for nearly half a minute or more, even with throttle & let it idle till eventually started popping back thru throttle body again. I’ve now got throttle body & intake removed. No obvious leaks noted but I’m replacing intake seals. I’m also suspicious of IAC valve. I’ll clean it & check it’s operation when I get engine running again. I’ll use petroleum grease on seals & o-rings & injectors.

 

Still backfiring & popping. Seems that when I spray carb cleaner around MAP sensor & IAC valve, engine smooths out. I’m still in need of advise.