Honda BF90A Stalling Problem..help me diagnose

ssobol · Posted: Mon Aug 10, 2015 10:29 am Post subject:

On a previous boat I had a Yamaha engine that had carbs. If the primer bulb was pumped up hard the engine would be flooded. Just took 2-3 squeezes before starting when cold. Never had a hard bulb and the engine ran fine.

I've never actually checked the bulb on my BF90D. Engine starts every time, and I never have to mess with it.

Kushtaka · Posted: Mon Aug 10, 2015 2:14 pm Post subject:

I have a similar motor, 2 years newer, with the opposite problem: I lose power at higher rpm, and it runs fine at lower RPM. I have two fuel filters with bulbs downstream from each. I need to regularly pump the first bulb to fill the second fuel filter. My honda tech says it's commonly a bad bulb in this situation and is replacing it, as well as all fuel filters. His list of possibilities were: bad bulb, old filter, clogged high speed jets, but a bad bulb is by far the most common culprit.

If it turns out to be something else I'll post here (still in the shop), but I suppose I'll never know if it was a bad bulb or old filters, as they will all be replaced at once. If it's the high speed jets I'll know, because the new bulb and filters won't work.

Blueback

Avidmagnum12 · Posted: Mon Aug 10, 2015 8:01 pm Post subject:

The carburetor version of the Honda 90 has 2 fuel pumps. Don't ask me why.

Wandering Sagebrush

busski · Posted: Tue Aug 11, 2015 12:35 am Post subject: Fuel pumps

It definitely is odd that there are two fuel pumps on the BF90a carbureted engine.

As for the high rpm issues, I recently started to have the issues at high RPMs as well. Suspected it might be a bad bulb, and replaced, but no help with the problem.

I would go step by step from cheap to expensive (bulbs, tank senders, fuel filter, fuel pumps) but what you are describing sounds exactly like the problem I had which was only solved (and immediately) when the fuel pumps were replaced.

Oh, and my pumps did have a gasket to make a seal with the flange. They didn't include them with the replacements so had to reuse. Was easy to miss as quite small and look "mounted" on the originals.

Blueback · Posted: Tue Aug 11, 2015 1:15 pm Post subject: Re: Fuel pumps

waterworld · Posted: Tue Sep 15, 2015 3:24 pm Post subject:

Hi guys...real newbie here.

My Honda 2001 75HP (4 stroke) stalls at idle and occasionally when accelerating over 2000rpm

The season here (Ontario, Canada) only has about 1 month to go.

I am planning on changing all sparkplugs and maybe carbs rebuild / cleaned in the off season.

In the meantime, I will try seafoam is the gas tank.

I am hoping to learn how to maintain the outboard as much as I can.

Does my logic make sense?

PS: Btw, does anyone have the Service Manual (PDF) for that beast? I have the Owners Manual, but it does not cover much from the servicing side. Wouldnt mind knowing where the idle screw is, etc...

Thanks!

busski · Posted: Thu Sep 17, 2015 9:28 am Post subject: Diagnosing a hesitation stalling

I would suggest a carb tune as one of the last steps in diagnosing an issue with the BF90A. There can be lots of reasons for stalling issues with this engine. The first and most common are fuel delivery issues. The last would be carb issues, and fixing those can be expensive as there are four, and they need to be synced after adjusting which requires a proprietary tool.

I would start with:

1) gas (is it new or gummy water infused ethanol blend?)
2) fuel lines from tanks to engine fully sealed at junction points?
3) sending unit from gas tank working properly?
4) primer bulb working properly?
5) In line water separator need replacing?
6) fuel filter in bottom starboard side of engine clogged/old/have water in it?
7) fuel pumps working as intended?
Cool

has the "BF90A Fuel bog" been addressed:
http://www.boats.com/reviews/boats/outboard-expert-honda-bf90-bog-cure/
9) spark plugs gapped and clean?
10) carbs cleaned with sea foam?
11) carbs adjusted and synced?

waterworld

busski · Posted: Thu Sep 17, 2015 10:11 am Post subject:

Ethanol can be a big problem for marine engines:

http://www.alloutdoor.com/2013/06/25/fishermen-beware-ethanol-fuel-deadly-outboard-motors/

And buying premium fuel won't help the problem, as it still contains ethanol, it just also contains higher octane gas and additives to help clean engines. You need to seek out ethanol free gas stations, which are often marine locations:

http://pure-gas.org/

Finally, always use a fuel stablizer if you're going to use the engine infrequently or keep gas for more than a month or two. I use:

http://www.goldeagle.com/product/sta-bil-fuel-stabilizer

waterworld · Posted: Thu Sep 17, 2015 10:24 am Post subject:

waterworld · Posted: Thu Sep 17, 2015 10:36 am Post subject: