Hello first time poster and am bringing this back up as I have the exact same issue. 2002 Yamaha 250 OX66 with 560 hours. I have already decarbonized the engine, replace Oxygen sensor with NGK equivalent, 3 new Yamaha LP pumps, new vst filter and gasket, new pressure regulator filter, new TPS sensor adjusted to .5volts, full throttle shows 3.7 volts, new temp sensor, fuel pressure is 34 and does not change when it surges,new T stats, new poppet valve, new water pump assy, new yamaha primer bulb, replaced fuel injector filters, spark plug boots all within specs, checked continuity on all 6 coils, both windings are good, stator coils ohms out at 300 ohms on each side, 60 v output on each side,I do not have a diva meter, tested pulser coil, 300 ohms form each white wire to gas, cleansed the grounds, 125 volts input on each coil, new plugs,Removed the kill switch and alarm comes on.Reset all the connectors on the CDI box, cleaned the yellow get home wire on the bottom of the cdi, this did have some corrosion, changed from one battery to another, charging 14 volts,problem is still there....
The one thing that has me confused is if I remove the TPS sensor, the surging issue goes away, any ideas? Thank you ahead of time for your help, Rick.
The one thing that has me confused is if I remove the TPS sensor, the surging issue goes away, any ideas? Thank you ahead of time for your help, Rick.
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