06 Bf150 rough transition from idle

I just purchased a boat with t

I just purchased a boat with twin Bf 150s. When you put the engines in the foward or idle detent position the idle becomes noisey and rough. Acoording to the tach it is idling around 800 rpm in gear and 1000in neutral. If you move the throttle ever so slightly it clears up and is completely smooth. This occurs mostly on the port engine but intermittently on the starboard engine. These engines have 300 hrs each. I have replced the racor filters and wandering if the small filters on the engines might be part of the problem. Engines run very strong above the idle transition and idle very smoothly in neutral. It seems that when you drop them in gear the idle is too low. Any ideas?

Thanks

"Idle should be 650-700 in neu

"Idle should be 650-700 in neutral, and drop no more than 50 rpm's when engaged, and should be very smooth after warm up. First things first. Make sure you're using new, clean gas. If you are not sure, attach a portable tank with gas you know is new and clean. Then pull the onboard fuel-water seperator filters and clean thoroughly per manual. Then replace the onboard fuel filters per manual. Readjust idle to specs per manual. That should straighten it out."

"Thanks W D Neal,

One que

"Thanks W D Neal,

One question, how many onboard filters are there that I can service without any special tools. I have also been told by a dealer that I can just clean the low pressure filter and re install. Is that a good practice? Do you think spark plugs would be worth looking at at this point? Where is the best place to find the filters and O rings. As far as gas I'm guessing the boat has been sitting apprx. 9months - year. Since I have been running i have added 150gal of gas and the problem is still pretty much the same, except every once and while it is completely smooth. The original racors did have some water in them . I'll change the new ones and see what they look like now with a few hours on them.

Thanks

"

"There are three filters. Firs

"There are three filters. First on the fuel line is the fuel-water seperator/filter. Second is the standard fuel filter, third is the high pressure fuel filter. No special tools required for removing and cleaning/replacing any of them. I believe it's all covered in the user's manual. It does not sound like your high pressure filter is the problem because they would typically cause you problems at higher speeds. If plugs were bad, it's likely that they would first fail at the high RPM's, not the low RPM's. Honda says change plugs at every 400 hours. (However, not a bad idea to remove plugs, inspect and re-install using anti-size grease on threads to make sure they don't freeze up in the block - if plug extraction becomes difficult, take it to a dealer. You do not want to break off a plug in the head - big bucks to fix.) I've been using the Racors for years, and had no problems. Best source for filters (at least the first time) is your local Honda outboard dealer. After you know you have the exact ones and proper part numbers, you can order them on line. If you have water in the new Racor's, then you will need to drain the main fuel tank so it's totally dry and you get all the water out - that's a pain, but must be done if you have water in the tank. Also, if you see a brown, flakey/gummy material in the bottom of the Racor's, or in either of the first two onboard filters, then there has been a phase seperation in the ethanol laced fuel. Your fuel tank will need to be both completely drained and cleaned - that's a bigger pain. God bless our federal government and their stupid fixation with ethanol."

I just pulled the racors off a

I just pulled the racors off and poured the fuel in a jar. There was not one drop of water in either filter and no brown material . Ihave probally burned 60 gallons through the new filters. I will replace the the standard filter and see what happens. Any fuel additive that you would recommend.

"Personally, I use Sta-Bil Mar

"Personally, I use Sta-Bil Marine. However, many around here (Lower Potomac & Chesapeake) use SeaFoam.

Sounds like your gas tank is okay, so let me know what happened with the onboard fuel-water seperator and fuel filter replacement. While you're in there, carefully check all the fuel line connections to make sure they're sealing well and no leaks. Do you have the shop manual for those engines? If not, it's a worthwhile investment to get one. The manual recommends replacing the O ring seals every time you clean, inspect filters."

I think the tank is good as we

I think the tank is good as well. The old racors had some rust and water in them from sitting. I think some of that made to the low pressure filter as they are the same color as the crud that was in the racors. I'll be replacing those Wed and running the boat again this weekend.

Thanks for the help.

"My schedule changed and I got

"My schedule changed and I got run my boat with the new filters. Idling out from the landing it was still a little rough but much better. When I got the boat on plane they sounded like different engines, quiet, and silky smooth. After 70 mile cruise the idle was smooth and quite. I think I'm going to run a couple hundred gallons through it andf change the low pressure filters again and it should be as good as it gets.


Thanks for the help W D


Britt"

Britt - sounds good. I noticed

Britt - sounds good. I noticed that the Hondas tend to be a little rough on start up but smooth out once they've had a good run. Probably no need to change out the filters again. Just do a good inspection and cleaning at the recommended 100 hours. Sounds like you're good to go. Happy cruising.