Wierd BF90 fuel problem - ideas?

[Chaps]

'98 Honda 90, about 1000 trouble free hours and running stronger than ever, however . . . lately the engine is exhibiting a fuel starvation stumble when taking off after restarts. <br /><br />Every time I restart the engine while I'm on the water it starts right up and idles OK but when I put it in gear and start giving it throttle it starts to stumble and almost die until I reach back and give the fuel bulb a couple of squeezes. <br /><br />The stumble clears up right away and the engine then runs like a raped ape with no problems until the next time I shut it off and then restart it after perhaps 20 minutes or more of being off. <br /><br />Something easy?

 

[khc1970]

Re: Wierd BF90 fuel problem - ideas?

Does it make any difference if you prime the bulb before a restart?

 

[Chaps]

Re: Wierd BF90 fuel problem - ideas?

If I prime it prior to a restart it will run OK. The carbs seem to be partially empty after sitting around a bit after a good cruise.<br /><br />This, on an engine where for 6 years I rarely, if ever, had to prime, even when stone cold and not run for a month. And never if it was warmed up.<br /><br />I was wondering about vapor lock. Also, the engine has 2 small fuel pumps, perhaps one of them is getting weak?

 

[Chaps]

Re: Wierd BF90 fuel problem - ideas?

OK, good input all around, thanks and I'll start checking these tips out

 

[khc1970]

Re: Wierd BF90 fuel problem - ideas?

If the engine run initially, that mean there's gas at the carb, the 'empty' is somewhere down the line, maybe the bulb isn't air tight?!

 

[MajBach]

Re: Wierd BF90 fuel problem - ideas?

Mine started doing this after 200 hrs, but i didn't relate it to the primer bulb. My bulb can be tight but after a few minutes of running, it's spongy. This seems normal however and this observation was present before the stalling on acceleration ( I know this because my first primer bulb had a faulty valve and I paid a lot of attention to the fuel line whilst trouble-shooting it). Anyway, after replacing the line, boat ran fine for the season and then the hesitation/stalling started. First thing I did was put a new line on- no difference. I learned last year that there is a TSB for that motor regarding an acceleration pump or vaccuum or whatever that causes this exact problem. I'd look into it. Try sustituting a fuel line from a marina and see if the problem remains. <br />MajBach

 

[rontbeamer]

Re: Wierd BF90 fuel problem - ideas?

Rebuild the carbs. The low speed jets are starting to clog. The first indication I had was had was stumbling on exceleration that later turned into a misfire periodically. The low speed jet is very easily clogged tube that is incredably small. Three out of four carbs were either partially or completely blocked in my motor. Rebuilding the carbs is pretty easy on these motors. Takes about two hours from start to finish. This typically becomes a problem on an engine that has sat for a period of several months and the carbs have been allowed to dry out.

 

[MajBach]

Re: Wierd BF90 fuel problem - ideas?

Personally, I'd wait for 'hondon' to reply to your inquiry before dismantling the carbs - he would know this problem likely. Maybe try 'Sea Foam' as well if the carbs happen to be clogged; it's supposed to make miracles.

 

[Chaps]

Re: Wierd BF90 fuel problem - ideas?

Roger on that, I'd like to get his input as well. As far as eventually going thru the carbs is that a procedure that is covered on the internet anywhere and does it require a parts kit?

 

[Redlake]

Re: Wierd BF90 fuel problem - ideas?

Hi all.<br />I am new here and see alot of help.<br />I have a 99, BF90 that I bought new in 2000. The motor had this same problem, or at least similar enough. I took it in to the dealer after 25 hrs and said that it started hard and that it would back fire at idle. When I would go to accelerate the motor would stumble and almost die unless I pushed the throttle up slowly. $ 200.00 later nothing had changed. I was so disgruntled that I have just lived with the problem till a month ago. I took the boat to a Honda guy in a different city and he said the carbs were way out of wak and the low speed on one was way lean.<br />$ 200.00 later the motor starts great but I still get a back fire at idle and until the motor is accelerating through about 1/3 throttle, it still stumbles. I have a friend with the same engine and he has had no trouble.<br />Thanks for any help.

 

[rontbeamer]

Re: Wierd BF90 fuel problem - ideas?

I bought the Soltec Manual and spent about $150.00 on parts. It took about two hours for the entire project. The engine runs better now than when I bought it new three years ago. The carbs are very simple to rebuild, really the simplist carbs I have ever cracked open. Pretty much just three jets to clean and a float setting. I actually had one bowl leak, opened it back up and put high tack on the rubber gasket sealed it back up and it was good to go. I actually got the original information to rebuild the carbs from a Honda Mechanic down here (Guiding season is over and they are swamped repairing boats. They are just happy to tell you how to fix the engine rather than getting more work they can't keep up with). <br />Anyhow this is the most common problem with these engines. I was told by one mechanic that 9 out of 10 problems with the Hondas are the low speed venturies clogging.

 

[Chaps]

Re: Wierd BF90 fuel problem - ideas?

Originally posted by MajBach:<br /> Personally, I'd wait for 'hondon' to reply to your inquiry before dismantling the carbs - he would know this problem likely.

Hondon, I've received some good input, was wondering if you might have anything to add?

 

[Lower Unit]

Re: Wierd BF90 fuel problem - ideas?

Replace the fuel bulb. They can go bad. By design, the bulb allows gas to flow only one direction. When the one-way-valve is defective, the fuel can actually drain from the engine........the instant remedy being to squeeze more fuel into the engine. Coupla bucks for a new one is the cheapest diagnostic tool you've got so far. Might also check the rubber hoses and connections from fuel tank to engine for cracks.<br /><br />Let us know.

 

[jobanf]

Re: Wierd BF90 fuel problem - ideas?

a problem thse engines can also suffer tho usually with higher hrs is the plunger return spring on the fuel pumps breaking.

 

[Chaps]

Re: Wierd BF90 fuel problem - ideas?

Thanks for all the help guys - I haven't solved it yet . . . am trying to find the time to work on it.

 

[MajBach]

Re: Wierd BF90 fuel problem - ideas?

Have you checked with the local dealer on the Service Bulletin {i.e. a recall that YOU have to have to pay for ) that this problem is typically caused by - as I first suggested? Might save yourself alot of time. ( I forget the name of the part - might be the plunger as suggested above. I know it's the big round brass thingy beside the carbs).