Honda BF35 fuel problem?

Paulrd27

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Mar 20, 2011
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41
Hello everyone,

I picked up a boat a couple days ago with a honda BF35 tiller model. I took it out and it had a couple problems. 3 guy said the motor hadn't been run in 3 years. It was kept inside, the inside of the engine looks very nice and clean (looks like whoever owned it took care of it). There was bad gas in it so I took out the gas an put new gas in with some seafoam. The motor would start first time every time, but then when I would put the idle down low it would stop. The only way I could get it to go is if I bring the throttle down, put it in forward gear and then quickly bring the revs back up. Also, when I would be cruising full speed, it would seem to run better/faster if I pulled the choke out half way. I'm wondering, is this a fuel related problem? There is also a 10 foot clear hose that goes from the tank in the middle of the boat to the engine. I can see a couple air pockets in this hose. Is this a problem? If this is a carburetor issue, is there an easy way to clean them without getting to deep in it? Any information would be greatly appreciated. Thanks guys!
 

Paulrd27

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Mar 20, 2011
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Re: Honda BF35 fuel problem?

Update: boat runs really slow. Seemed like it was only running on 1 cylinder. Checked the plugs, 2 were dry. Looked like only bottom cylinder was running. Checked spark and only bottom was good. Bought new plugs and installed, took out on the water and it was still the same. The engine was jittering and only said I was going 12mph on my fish finder (motor is on a 16ft aluminum lund). Took off the plugs, looked like bottom 2 were firing and the top one still looked new. Checked spark on all of them and it looked like they were all firing. Could it be my coils?
 
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westcoaster90

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Re: Honda BF35 fuel problem?

sat for 3 years with most likely ethanol fuel in the carbs. pull the carbs off to clean. when you remove the air screws from the carbs turn them in counting how many turns. this way you know how many turns out to set them at. be sure to do this on every carb as they may be slightly different. the carbs are synchronized and being sure those screws are set exactly as they came out will ensure smooth running. keep the carbs organized separately and install everything exactly how it came apart and every part in the exact same place. I clean carbs by giving them a good brush in acetone then hit them with compressed air. once you have it all back together she'll purr like a kitten :rockon: I have done way to many carbs on Honda engines and more often then not the intake gaskets rip but there are times they can be saved.
 
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Paulrd27

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Re: Honda BF35 fuel problem?

Thanks westcoaster, I tried to post a picture of one of the cards. Things were caked up and looked like they weren't even getting fuel! Your right, it does purrr like a kitten now :cool:. Only thing is, I couldn't wait to get gaskets so I just used what was there. It doesn't idle too good in low gear. When I bring it down low enough to put in gear it dies before it engages. Do you think if I replace the gaskets this will go away? If not, what else could I do? Thanks again!
 

westcoaster90

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Re: Honda BF35 fuel problem?

did the gaskets actually rip? if they didn't rip I would just run it with those gaskets but if ripped replacing is a must. ripped gaskets can cause very fine air leaks which could make it struggle to pull gear. how did you clean the carbs? exactly how i said? it is possible that if you didn't use compressed air something got missed. where your at now i would make sure your choke is engaging and disengaging properly. if all is good, gaskets aren't ripped and you are sure you cleaned those carbs good with compressed air then i would synchronize the carbs. if the gaskets aren't ripped they will work fine. i have never had an issue reusing a non ripped gasket. oh ya and just for the hell of it you should replace the plugs. after 3 years of sitting i would do it even if they were near new when stored.
 

Paulrd27

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Re: Honda BF35 fuel problem?

I changed the plugs and none lf the gaskets ripped. The only thing I didn't do was pull the air screws on the sides of the carbs. I didn't want to mess with any synchronizing because I'm not sure how to do it. Also, how do I test if my choke is engaging properly? Thanks a bunch for the replies!
 

westcoaster90

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Re: Honda BF35 fuel problem?

what you would want to check is if your choke butterflies in the carb are opening fully when the choke is disengaged. if they don't open fully then it may cause a rich run condition if they are closed enough which would make it not want to pull gear at idle. you have to remove the shroud off the back of the carbs so you can see them open and close. while your add it check to be sure your throttle butterflies open at the exact same time. they are adjustable in the linkage that connects the 3 carbs together. I have never had a Honda not pull gear at idle. I've even seen them pull gear with dead cylinders fine. really how low of an idle are you doing? I would also make sure your plug wires and boots are healthy to be sure they aren't arcing. also inspect coils for cracks. I have never seen a coil on those Honda's crack before but it could happen. like I said. I have seen those Honda's pull gear with dead cylinders so I doubt it's your issue but it's good to check anyways. if it was a 2 stroke I would be telling you to do a comp test but I have never seen those honda's be more then a few psi out between the 3 cylinders. if you are still having issues and are absolutely sure you cleaned those carbs out good a synchronization will be in order which you could perform yourself or get a shop to do it. you just have to see if a shop will lend you there synchronization gauges. my local shop here lends me theirs when I need them. one last thing. do you notice it backfire out the exhaust at all? or is it hard to start? I have seen the valve lash in these engines way to tight before. probably not because of Honda but because somebody who didn't know what they were doing adjusted them. in the few times I have seen this issue it would backfire out the exhaust. pulled the valve cover to find the exhaust valves of 2 cylinders were being held open by the rocker. adjusted them and it ran fine. the thing still pulled gear though but just barely. I know this is a big list of things to check but I am just trying to get the idea's to you. if the motor has high hours it is a good idea to adjust the valves just for the hell of it and if you have a service manual it is a very simple job even for a person not familiar with it. it is very hard to diagnose something without being there but i'm sure we can get you going again.
 

Paulrd27

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Re: Honda BF35 fuel problem?

Checked the choke, looks fine. It does backfire a bit. If I get it in gear then move at low speed, it'll back fire ounce and a while. I took the carbs off again and sprayed some gum out in all the jets and put some compressed are in as well. I tried turning the idle screws in a bit further all a half a turn each to the point where I got all the way in and it still ran the same. Shouldn't the revs be getting higher as I turn it in? I changed the fuel filter and gaskets as well, still the same. I haven't changed the oil though, would that make a difference? I called the local marine shop, they wanted 200-300 for a carb sync. I don't know if that's what I should resort to or not, what do you think?
 

westcoaster90

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Re: Honda BF35 fuel problem?

sorry man been busy and didn't notice you post. if your getting backfires a carb sync wouldn't fix that unless your tuned lean to begin with. It is very hard to diagnose something like this without being there in person but I still feel like it is fuel system related. when you backfire would you say it comes out of the exhaust or intake? if so your valve timing will be off. if it just sounds like a backfire that goes no where it is more likely a lean misfire. I am not there so this is very hard to diagnose but I have owned and worked on many Honda's and like I said before I have seen them run on 1, 2, and 3 cylinders. to fix the issue you describe I only ever had to clean and resync the carbs. problem solved. you might wanna do a compression test on that engine also. I have never seen any of the honda outboards go out far enough to make them not run right but you never know. good luck on this as there isn't really to much more I can add without being there in person.
 
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