Will not idle without choke- Fuel pump? 1998 40 hp

Motor is a 98 BF40A, starts ok but runs rough, needs choke on and fast idle arm up or it stalls. If I use the manual choke I can advance the throttle and it speeds up. I think it needs a carb cleaning but the mechanic at the marina says it needs a fuel pump. When it's running I can squeeze the primer bulb and it doesn't improve anything. New boat to me so I don't know the service history and I have no experience with the mechanic good or bad. I'm in a marina that doesn't allow outside vendors so I don't have a lot of choices.

Re: Will not idle without choke- Fuel pump?

Check my post to your other thread http://www.marineengine.com/boat-fo...8962-Whats-a-reasonable-charge-to-clean-carbs

Mike

carburator idle jet is clogged. leaves it running leen, not to due with the fuel pump.

one of the carburators jets could be clogged or a float could be hung so if you start it you can tap on the float bowl of each carburator pretty vigorously but not to damage anything. It sometimes can dislodge the float and allow fuel to that carb.

Turns out it was the fuel pump.

I am not a betting man, but I would have lost big money on that one.

Glad to hear it worked out and you can use your boat.

Mike

Put me down for a big "L" too. That's why some of us can't live in Vegas.

Premature celebration, it wasn't the fuel pump. Still has the same problem,not as bad but still not running right and on the verge of stalling. I was able to play with it and did a cyl balance test by pulling plugs while running. Top plug had no change in rpm, other two had significant rpm falloff. When I opened the fuel bown drain on that carb fuel ran out and the idle improved. When i shut it it returned to poor running. I pulled the carbs to take them home and will do a cleaning this week. For those betting i think it's a push and the money is still on the table

Pay close attention to the air passages as well as the idle passages on the top carburator. Check the long tube going up through the carburator. It is most likely plugged up.

Also, check all the long tubes (idle jets) for minute cracks in them...with a magnifying glass. The older 40's and 50's seem to have an issue with these. It will cause irratic or poor idle.

Once you think you have it cleaned, check the idle circuit by putting the idle mixture screw in just a little then take some brake clean with the narrow straw on it and stick it up where the idle jet seats in the upper part of the carburator. There are a few very small holes (pin size) at the top of the barrel of the rear of the carburator. When you shoot the brake clean, you should see it spray nicely out of all of those little holes. If they do not, you will have to take a small wire and probe back through them and clean them out. That is the path of the fuel for idling as well as transistion to faster speeds.


Good luck.

Mike

Thanks, all the help has been appreciated. How hard is the synchronzation? I'm lining up three vacuum gauges and trying to find adaptors. It looks like its a 5mm hose barb,is that right?

I do not know the size of the barb. You just have to be patient when you synchronize. It is very important to get it right. It will really help the way your engine runs.

Mike

It was the carbs after all! Took the off and cleaned them all. Thanks for the pointer on the port that squirts out the barrel. When i tried brakeclean at first nothing came out then after a while i got a dribble then a clear squirt. All in all four cans of brakeclean for three carbs ( in addition to a soak in carb cleaner and hitting it with an air hose).

Once on the boat it started up fine and ran pretty smooth. I am having a problem with synchronization. I got adaptors and three vacuun gauges but no snubbers. When i started the motors the gauges just went wild. I tried to crimp the hose but when it stabilized it was around 10 in/mm. Would snubbers show a higher vacuum or did the timing belt slip? Any way to verify the timing without pulling the flywheel?

Do not worry about the actual vacuum reading. The top two carburators, just have to be the same as the bottom carburator.

You can verify timing without pulling flywheel. You have to take off the plastic cover. There is a vertical line with a T next to it on the outer circumference of the flywheel. It should align with a mark on the top of the power head that doubles as the port side base of the lifting eye.

With that T is alignment, the T on the cam pulley should align with an arrow on the powerhead next to the other end of the lifting eye.

If they do not align at first, rotate the flywheel one rotation.

Remember to rotate the flywheel counterclockwise. Check the arrow on the top of the flywheel.

This is easiest to do if you remove the spark plugs.

Mike