1998 Honda BF90A Won't idle.

1998 HondaBF90A. Rebuilt carburetors this summer and motor ran like a dream for severalmonths. Last time it was used was about a month ago and it ran good. Tried to start it this weekend and itsputtered and kept cutting off. It will run with full choke and partialthrottle but when throttle is increased it cuts off. When choke is pushed backin slightly it revs up and then cuts off. It won't start at all without choke even after warming up. It will run all day at about1500 RPM up to about 2500 RPM with full choke and partial throttle. Thought itwas bad gas so substituted new gas, no help. Used Seafoam and did decarb, smoked a lot at first but then cleared up, butstill didn't help. Maybe it just doesn't like cold weather! Any ideas?


(Carburetorrebuild this summer included new manifold and air box gaskets, new jets, newfloat valve, new O-rings, new fuel filter, and soaking and cleaning carburetor metal parts)

It's sounds like it's still a fuel problem. My guess is the carbs are gummed up again and need a clean out. Also check your fuel lines and fuel filter are flowing freely and replace the filter if not done for a while or no good. I have seen the inside of an old fuel line break down and turn to sludge then blocks up the filter. There are many small holes in the carbys and fine tolerances that can block or stick if fuel is left in there to evaporate. Do you drain the bowls when not in use? You could try filling the bowls and giving the carbs a good squirt all through with carby cleaner and leaving it over night before draining and running clean fuel. Or just pull them off and apart and cleaning thoroughly. Start with the easy checks though like filters and lines. Oh yeah, and make sure you have your fuel tank breather open and its letting air into the tank!

Thanks skronkman!
I agree,sounds like a fuel delivery problem. Just seems kinda unusual for carbs to be gummed up so soon after complete rebuild. These carbs were completely torn down and cleaned last summer, I mean spotless. New jets, new fuel filter, etc. Only things that were not cleaned or replaced were the two fuel pumps and the hoses from the fuel pumps to the carburetors. Also installed a fuel filter and water separator between motor and main tank. Motor ran like a champ for three months and last time used about a month ago. Only thing changed is the outside temperature. I've got a little 3 gallon gas tank that I use for decarb, I put fresh gas in that and connected it to motor to make sure it wasn't the gas in the main tank. I put Stabil in all my gas and do not use gas that contains ethanol. Maybe something that had built up in gas lines or fuel pumps over time could have worked loose and clogged up carbs but doesn't seem like it would have taken that long to break loose and doesn't seem like it would have clogged up all of the carbs at the same time. The carbs have gas mixed half and half with SeaFoam in them now. Hoping that if something is in there it might dissolve. I'm not looking forward to taking those carbs apart again.

If dirty fuel got in it could happen quickly. It happened to me once within an hour of swapping to a dirty tank with old fuel. Good luck with the seafoam, I haven't seen that product in Australia but I've heard good reports from plenty of people in the US. If no luck the I would consider pulling them off and soaking them over night in cleaner then blasting them carefully with an air compressor while in bits. You will have to rebalance the carbs when put back together and on the motor. Again, be sure to check all the easy things first before committing to pulling them down. If squeezing the fuel bulb helps then the fuel pump is another possibility and that is easier then the carbs to pull and check/clean.