Yamaha 4 stroke 200hp misfiring

[isolamia]

I have two 2001 Yamaha 200hp motors, last time I went out my port motor will not accelerate when I increase the throttle. It starts misfiring at aprox. 1800 RPM, sometimes it will increase to 2ooo RPM or maybe 2500 RPM and then it will go down to 2000 and will oscillate in that range. The only way I can get it to operate correctly is to shut the engine off and as soon as it starts give it throttle and in most cases it will run properly. When the engine is misfiring I can hear something arcking and the engine will sputter. I checked the spark plugs wires and they all look good. The engine only has 400 hours. If I can get it up to speed the engine will operate just fine, its on the starts that it give me problems. Your advice is greatly appreciated.

 

[rodbolt]

Re: Yamaha 4 stroke 200hp misfiring

hello<br /> we have to isolate it to fuel or ignition. by the fact that it will run okay sometimes we can pretty much eliminate mechanical. make sure all battery cables are clean and tight, go from the battery,through any switches,splices and engine rigging tubes. the motor is EFI and the ign is TCI. all use 12 volts and are flaky with bad battery connections. depending on your seriel number there may be an update to the driver circuit. does the digital tach display do anything unusual when its stuttering?<br />what is the model number. my book shows the f200 starting in 02.you will need to test the high pressure fuel rail to insure adeqate fuel pressure. the tester is about 60 dollars at napa. to test the TPS will require the test harness from yamaha and a DVM. most times its something other than the motor. could be a low pressure pump failing. it cycles on and off at low speeds. I have seen some grounding issues cause problems like you describe. have you checked the fuel filter under the airbox ?<br /> if you hear the injectors clicking loudly it usually means they have no fuel. try rapidly pumping your fuel primer bulb when this is occuring.there is also a filter that needs maint in the vapor seperator occasionally

 

[isolamia]

Re: Yamaha 4 stroke 200hp misfiring

Thank you, for your quick responce. I will check these problems out. Your last observation seems to be a good posibility. You are right the engines are 2002.<br /><br />Again, many thanks.

 

[seahorse5]

Re: Yamaha 4 stroke 200hp misfiring

Inspect closely the battery cables where they attach to the motor between the intake "runners". Sometimes they are not flat against the bracket and are cocked at an angle, making an intermittent connection and causing the motor to misfire.

 

[rodbolt]

Re: Yamaha 4 stroke 200hp misfiring

seahorse.<br /> I did one a few weeks ago like that. seems whoever did the floppy bushing update pinced the rubber sleeve under the + cable lead. made it do funny things