Honda BF75L starts, high revs but stalls out at idle

[MaxGlide]

Hi All,

I have a Honda BF75L, four stroke, serial number 1602811.

Motor was running beautifully about a month ago. Yesterday, got it to start up on choke and it will stay running if we rev it and keep it in higher RPMs. As is it stalling out we can stop it stalling by cranking the throttle and revving it but it will stall out if brought to idle.
The only "filter" I can find in the parts manual is the strainer inside the fuel pump.
Some research I've done has pointed it to possible clogged needles, or such. My knowledge of carbs floats between very little to not-too-much. I guess my best bet is to take it to a Honda service centre.

 

[km1125]

Is this a 7.5 HP or 75HP? Might sound like a silly question, but it seems like Honda used BF75 for both. Not sure if that's just and "older" vs "newer" thing or if there was some other methodology.

If it's a 7.5HP, then it's probably very similar to my BF8A (8HP) and I had a very similar problem. Turns out the carb needed a really good cleaning. There's a little passage inside that handles the mid and low speed fuel circuits. Something in mine got plugged, so I could start it using the choke but it wouldn't stay running unless I was pretty much at full throttle. I took the carb off and cleaned it (once) and it didn't help. Took it off and cleaned it again (twice) by soaking it for a few hours in carb cleaner, and it still didn't help. Took it off a THIRD time and soaked it overnight and the problem was GONE.

If it's the 75HP, then I don't have any suggestions.

 

[presleymarkw]

Hi All,

I have a Honda BF75L, four stroke, serial number 1602811.

Motor was running beautifully about a month ago. Yesterday, got it to start up on choke and it will stay running if we rev it and keep it in higher RPMs. As is it stalling out we can stop it stalling by cranking the throttle and revving it but it will stall out if brought to idle.
The only "filter" I can find in the parts manual is the strainer inside the fuel pump.
Some research I've done has pointed it to possible clogged needles, or such. My knowledge of carbs floats between very little to not-too-much. I guess my best bet is to take it to a Honda service centre.

I have the short shaft version. That is a pretty typical symptom of needing a good carb cleaning and adjustment. If you are mechanically inclined it's not all that hard, I finally learned cause I got tired of paying for it. Watch a couple youtube videos. Take pictures before of all linkages and hoses so you put things back together right. This is a pretty simple carb. Good one to learn on.

Or you can pay to have it done.

 

[presleymarkw]

I have the short shaft version. That is a pretty typical symptom of needing a good carb cleaning and adjustment. If you are mechanically inclined it's not all that hard, I finally learned cause I got tired of paying for it. Watch a couple youtube videos. Take pictures before of all linkages and hoses so you put things back together right. This is a pretty simple carb. Good one to learn on.

The only needle valve I remember is on the outside of the carb. It can be removed just looks like a screw. You can run some thin wire (I used a guitar string) up from the end to make sure it is clear. Thats the pilot jet. It clogs easily but just usually makes the engine really hard to start in my experience.

Or you can pay to have it done.

 

[MaxGlide]

Is this a 7.5 HP or 75HP? Might sound like a silly question, but it seems like Honda used BF75 for both. Not sure if that's just and "older" vs "newer" thing or if there was some other methodology.

If it's a 7.5HP, then it's probably very similar to my BF8A (8HP) and I had a very similar problem. Turns out the carb needed a really good cleaning. There's a little passage inside that handles the mid and low speed fuel circuits. Something in mine got plugged, so I could start it using the choke but it wouldn't stay running unless I was pretty much at full throttle. I took the carb off and cleaned it (once) and it didn't help. Took it off and cleaned it again (twice) by soaking it for a few hours in carb cleaner, and it still didn't help. Took it off a THIRD time and soaked it overnight and the problem was GONE.

If it's the 75HP, then I don't have any suggestions.

Hi there,

It is the 7.5 hp and that is exactly what it needed, a good cleaning. Unfortunately, when it comes to carbs, I am not well-versed at all and had to pay the $195 an hour shop fee to have it cleaned. Now it runs perfect!

 

[MaxGlide]

I have the short shaft version. That is a pretty typical symptom of needing a good carb cleaning and adjustment. If you are mechanically inclined it's not all that hard, I finally learned cause I got tired of paying for it. Watch a couple youtube videos. Take pictures before of all linkages and hoses so you put things back together right. This is a pretty simple carb. Good one to learn on.

Or you can pay to have it done.

Yep, had to pay, my carb knowledge is zero to none! I did pull the Mercruiser 140 motor, do all the seals, gaskets, motor mounts, fuel line, exhaust flaps, and other wrenchy stuff but the finnicky carb is out of my league… for now!

 

[MaxGlide]

The only needle valve I remember is on the outside of the carb. It can be removed just looks like a screw. You can run some thin wire (I used a guitar string) up from the end to make sure it is clear. Thats the pilot jet. It clogs easily but just usually makes the engine really hard to start in my experience.

Anyone have good protocol to follow to minimize carb gum ups?

 

[presleymarkw]

Anyone have good protocol to follow to minimize carb gum ups?

When I'm taking the boat out of the water, if I don't think I'm using it I the next day or so, I pull the fuel line off rather than killing the engine. It will run until it drains the carb bowl. The idea being that very little is left in the bowl so when it evaps it leaves much less gunk each time. Rather than the gunk from a full bowl of gas evaporating.

 

[km1125]

When I'm taking the boat out of the water, if I don't think I'm using it I the next day or so, I pull the fuel line off rather than killing the engine. It will run until it drains the carb bowl. The idea being that very little is left in the bowl so when it evaps it leaves much less gunk each time. Rather than the gunk from a full bowl of gas evaporating.

Yep, I do the same. I try and judge how long it will run and pull the fuel line off as I'm coming back to the dock. While I'm tying up it usually just runs another minute or do and then dies.