Honda BF90A Stalling Problem..help me diagnose

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.
 
busski":2xev4gn6 said:
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.
Click to expand...

I stand corrected and amazed-- 2 fuel pumps--hmmm? That sounds like double trouble when they pack it in and double the cost. My BF50-A fuel pump does not have an outer flange gasket - its the edge of the diaphragm itself the appears to double as a gasket.
Still scratching my head -- what in hell was the design engineering thinking when they placed 2 fuel pumps in that model motor. However, I will guess and say if they run off separate cams obviously they would pump double the amount of fuel- but why - who needs it.
 
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!
 
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?
8) 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?
 
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
 
busski":1786io70 said:
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
Click to expand...

Awesome, the previous owner had told me gas with ethanol was ok.

My boat does not sit around long, a couple of days at the max.

Thanks for the enlightenment !
 
busski":23qktwt2 said:
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
Click to expand...

Awesome, the previous owner had told me gas with ethanol was ok.

My boat does not sit around long, a couple of days at the max.

Thanks for the enlightenment !
 
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