2001 Yamaha 90

Have a 2001 yamaha 2 stroke that sat in a dealership for three years and than was sold to the dealership I work at<br />Motor starts but runs rough.When it got to the shop it was missing the sparkplug ends and a few other items.<br />When I start the motor I can pull the plug wire off of the middle cylinder and it does not effect the engine at all.I can hear the spark snapping to the plug when I put the plug end back close but it seems to have good spark,the bottom cylinder is the same.The only cylinder that seems to be firing correctly is the top one.<br />I took botton two carbs off and checked,both carbs are clean and free of any dirt etc.<br />It almost seems as if the motor is starting in the RPM reduction mode.Oil tank is full<br />Compression is good all cylinders and just switched the plugs.<br />When running I can put my hand in front of the two bottom carbs and it is pulling gas into the cylinders.<br />Any suggestions...........

Re: 2001 Yamaha 90

double check the carbs and fuel pump. then index the flywheel and use a timing light to verify the spark is occuring at the right time. sometimes motors sit upside down in the crates and the old gas solidifies in places you dont normally see.<br /> good luck and keep posting

Re: 2001 Yamaha 90

Would incorrect sparkplug wire ends have an effect?

Re: 2001 Yamaha 90

possibly. if they are red test them with an ohmeter. also test the crank position sensor output. unplug the yellow emergency lead and see if the idle improves. also make sure the manual primer flag is in the auto position.<br /> good luck and keep posting

Re: 2001 Yamaha 90

Rodbolt,<br />Thanks for the info,the caps are black and I tested them with a ohm meter and they test at 5.75-6.00.I cannot find what they should be anywhere.<br />What yellow lead are you referring to?<br /><br />I cannot find if the plug caps should be a resister type cap in any service manual.My thought is that if the caps are a resister<br />type and the motor does not call for a resister cap,that will cause the motor to fire late,correct?

Re: 2001 Yamaha 90

hello<br /> probably not. the yellow wire is looped and comes out from under the CDI. it allows the engine to run on fixed timing in event of a micro-processor failure or a crank position sensor failure. the pulser coils will set ign timing .<br /> good luck and do you have a service manual for this engine?

Re: 2001 Yamaha 90

Rod,<br />Found the yellow wire and unplugged it,no improvement.Should this eliminate the ign system as a problem?Should I further search the carbs as a problem?<br /><br />No,do not have service manual......

Re: 2001 Yamaha 90

yes double check the carbs. but to do any electrical tests you have to have a service manual. index the flywheel marking TDC on 2 and 3. then verify spark occurs at the proper time.<br /> good luck and keep posting

Re: 2001 Yamaha 90

Rod,<br />Checked timing at all three cylinders and it was good.Pulled plugs again to check firing.top and bottom plugs black,middle plug still like new as if it never fired.The electrode was still white?<br />Motor runs,but runs poorly.<br />Found a black wire hanging under carbs that appears to be a ground for the oil level sensor.Hooked up to ground and now when I turn key on alarm sounds,and stays on while motor is running.<br />Help,please help...........

Re: 2001 Yamaha 90

hello<br /> your going to have to test the sensor, if you have a 703 side mount control look near the 4 wire trim sensor harness under the hood near the 10 pin main harness and see if the gray wires are hooked up. if they are unplug the gray lead at the bullet connector. some 703 boxes wont accept the gray lead and will sound the alarm with key on engine off. do you have the yamaha digital tach? if so does it show any visual alarms when its buzzing?<br /> if the porcelain is black change the plugs. I still think you have carb problems. remove them, remove the fuel bowl ,remove the black rubber plug that seals the idle fuel passage and remove the idle fuel jet. make sure the passage from the main jet well to the idle fuel jet is clear. then make sure the jet is clear. then using a can of carb cleaner and safty glasses spray into the idle fuel passage and insure it sprays from the idle ports at the top of the carb throat just aft of the butterfly. it just sounds like a fuel problem.<br /> good luck and keep posting

Re: 2001 Yamaha 90

Rod,cleaned the carbs,twice,still no good.The red manual primer flag is in the closed position.The only lettering on the carb for position is open and close.There is an enrichner on the motor so I closed the primer.<br />Still appears to only run on one cylinder at low end.(top cylinder)but does somewhat clear up at midrange.When checked plugs are somewhat oily.<br />It almost seem that there is something preventing the motor from firing correctly,such as a RPM reduction mode........

Re: 2001 Yamaha 90

hello<br /> rpm reduction would give no midrange or top end. I still think you have a fuel problem. what was the motor at the dealer for? is a a brand new or new to you motor?<br /> have you tried running it with the airbox removed and covering the non running carb throats with your hand to see if you can force it rich?<br /> did you solve the alarm problem?

Re: 2001 Yamaha 90

This is a brand new motor,it sat at a dealer on a boat for three years and was bought by this dealer after the first went broke.<br />I have had the airbox off while working on the carbs and kept them off.<br />When I place my hand in front of the carb mouth while the motor is running my hand will get wet but the motor speed or sound does not change.I have attempted to spray gas into the carb while the motor is running and it has no effect.<br />When I pull the plugs out they are wet to the touch,and somewhat oily.<br />I again checked to see if the motor is firing and it is firing on all three cylinders using a timing light.It fires at the correct timing marks indexed on the flywheel.<br />The alarm isssue is solved,thank you....