94 Yami 90hp stumbles at lower rpm's

[freetime99]

Have had carbs cleaned and rebuilt recently, the bottom cylinder has spark but is not firing until after getting on plane, then engine runs OK. Also have replaced fuel filters and spark plugs. When it's idling, it's rough, sometimes cuts off. You can remove the bottom plug wire and it makes no difference (shows that is the suspect cyl.) Spark chech shows all plugs firing.What would cause just the bottom cyl. not to get fuel at low speeds but run OK at higher rpm's ?

 

[freetime99]

Re: 94 Yami 90hp stumbles at lower rpm's

Hey RODBOLT , any help on this one?

 

[robert graham]

Re: 94 Yami 90hp stumbles at lower rpm's

Maybe bad fuel pump diaphragm causing fuel to get sucked directly into that cylinder causing very rich mixture. Check spark plug in that cylinder for fuel-wet condition. Rodbolt may have some other ideas on your problem also.

 

[99yam40]

Re: 94 Yami 90hp stumbles at lower rpm's

Too rich or too lean both will not fire, pull the pump off block but leave hoses attached and pump primer bulb to see if fuel comes out the pulse port. If pump is good the look at the carb

 

[freetime99]

Re: 94 Yami 90hp stumbles at lower rpm's

Hey RodBolt .......... can you lend your experience to this problem -Thanks