1998 90 hp

i have a 90 honda that will not run with out the choke on. Carbs have been cleaned. i did the cleaning but i did not mess with any adjustments. pulled bowls, did not take floats out. put each carb back exactly where i took it off. it is getting gas fine. can any one tell me why it won't run without being on choke. already checked pumps and filters. any suggestions? Doc

Most likely, the carbs are still not totally clean.

If you did not remove the float and needle I am assuming you probably also did not remove all of the jets and main nozzle and clean them individually. Also, you need to be sure that all of the passages are clean.

Check out 18, 20, 39 and 40 on the parts breakout below. They are the most likely to get clogged. 18 has an especially small hole through it. It is very hard to clean efficiently. Even when you think you have it cleaned, there is generally particles still in it due to the construction of the jet. The passage is smaller than a pin.

I generally replace them, especially on older motors.

39 is the slow jet. 40 is the main jet. 18 is used at idle and transition. 20 is the main nozzle.

Also take out the idle mixture screws, so you can clean that passage thoroughly.

http://www.boats.net/parts/search/H... JPN, VIN# BBBL-3000001/CARBURETOR/parts.html

When you put the idle mixture screws back in, screw them in until they lightly seat. Then turn them back out 2 1/4 turns.

Floats are set at 10.5 mm. Generally, if they are parallel with the base of the carb when the carb is held upside down, gets them pretty close.

Pay most attention to the bottom two carburators. Generally, the bottom is the first to clog.

Hopefully, you have replaced all of the o rings and gaskets.

Make sure the little hoses (about 1/4 od behind the carburators are not cracked.

The long skinny jet (#18) sometimes develop cracks at the base of the tubes.

It is helpful to have a Honda shop manual to do these.

After all the cleaning is done, they should also be vacuum balanced. But, as long as you put all the carbs back where you got them, the existing balance might not be disturbed. That still does not mean they are balanced. The motor will run, even if the carbs are out of balance, just not as smooth as it should. So, balancing is not your main problem at this time.

I just did a set of these today, and to do a thorough job, it does take a little time. So be patient...

Mike

Hi,
I just wanted to add to what Mike said that there is a passage in the bottom of the float chamber (or "bowl") that can get clogged with particulates and cause trouble. Make sure that you verify that the drain in the bottoms of the bowls are clear so that they will work for you when you need them and while doing that, you will see another passageway that is the vacuum break for the chamber and clean that thoroughly too.

Remember that all liquid fuel, no matter how carefully refined or filtered, will contain some moisture. That moisture will not mix with the fuel well and will eventually seperate and pool in any container, including your carburetor float chamber. It is that moisture that gets you if you don't drain the carbs REGULARLY. Use Stabil fuel stabilzer or dose your tank with Sea Foam and that will help. Do not use fuel that has been sitting for long periods of time, particulary if it isn't in a sealed container.
Don't worry, you'll get it.
Good luck.