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BF50D Cranks, pumps gas, wont start/runs rough

M

menogyn

New member
I have an early 00s Honda BF50D outboard running on a pontoon that is used multiple times a day throughout the spring, summer, and fall. Yesterday, while doing a regular run across the lake to pickup supplies, the motor unexpectedly cutout and would not start again.
When troubleshooting both immediately after and later in the day when it had completely cooled, the engine would either crank and shudder, or start and run for a couple of seconds (shuddering and coughing) before dying again.

What I have tried so far:
I have ensured that the engine is recieving CLEAN fuel (took apart all filters and pumped gas through all lines to rule out blockages/water in the lines). Battery is good, and I ensured all fuses were installed correctly and not burned out. Replaced the spark plugs even though I had just replaced them this spring. Noticed an oily substance and a higher than usual amount of soot in the spark plug block mounts. Cleaned the air filter. Prior to replacing spark plugs, engine had only started once during troubleshooting. It started and ran (again, roughly and only for a couple of seconds) 3/7 times I tried after I replaced the spark plugs.

My question is this:
I live very far away from a dealer, and since this motor is semi permanently attached to a rather large pontoon, I'd rather not have to tow it anywhere. Is there anything else I should try? Any last resorts? I have plenty of tools and experience working on land vehicle engines. Any help is greatly appreciated!
 
Hi,
Not an expert on these but I'll try to help you brainstorm it a bit.

First off, the 50 D is fuel injected so that's what my comments are based on.

Some basics to check would first be to check your kill switch and make sure it isn't partially activated or broken.

Can you hear the high pressure fuel pump run for 2 to 3 seconds when the key is cycled to the ON or Run position? (Not start!)

Does the fuel primer bulb stay firm? Have you tried squeezing the bulb to keep it running?

Is your fuel tank vent fully open and unclogged?

Try running with tank cap loose to allow air in. Check condition of fuel pickup tube.

Did you do any service to the Vapor Separator like draining it or cleaning the fuel strainer screen?

The sudden stopping is concerning because something may have broken. I wouldn't try running it anymore until checking under the timing belt cover and making sure that the belt is tight and the timing marks line up correctly.

There are other things to check but I have to run for now.
 
All of the above, w/2 thoughts. A timing belt issue on a motor this new would be pretty unusual, unless you're talking commercial use/really high time.

When it went down, was it like you shut the key off, or did it gradually slow/start puttering/runnig erratically before it stopped? The answer here COULD supply a useful hint. If it just shut down like you turned the key off, my bet is it would be an electrical issue - like the emergency cut off. If it gradually slowed or started sputtering before quitting, I'd be looking at a fuel supply issue. Best of luck....
 
Alan,
I don't put much faith in timing belt tensioners and their associated springs. I've seen 'em fail right out of the box.

Also, there was a recent case here on a twin (BF20 D... no tensioner) where the cam pulley inexplicably cracked and moved allowing the belt to jump off and the engine died instantly.

I would err on the side of caution....

....although ....

....I often do err due to "other things" :>)

.
 
jgmo said:
Hi,
Not an expert on these but I'll try to help you brainstorm it a bit.

First off, the 50 D is fuel injected so that's what my comments are based on.

Some basics to check would first be to check your kill switch and make sure it isn't partially activated or broken.

Can you hear the high pressure fuel pump run for 2 to 3 seconds when the key is cycled to the ON or Run position? (Not start!)

Does the fuel primer bulb stay firm? Have you tried squeezing the bulb to keep it running?

Is your fuel tank vent fully open and unclogged?

Try running with tank cap loose to allow air in. Check condition of fuel pickup tube.

Did you do any service to the Vapor Separator like draining it or cleaning the fuel strainer screen?

The sudden stopping is concerning because something may have broken. I wouldn't try running it anymore until checking under the timing belt cover and making sure that the belt is tight and the timing marks line up correctly.

There are other things to check but I have to run for now.
Click to expand...
I've checked/done everything you've described except listening for the pump and checking the timing belt. I made sure to clean out the seperator, and I also pumped fuel via my tanks hand pump as far as the fuel rail with no issues. As Alan asked, it was a slow puttering/coughing off, not an immediate shut off. I'll listen for the pump and post a other reply
 
Ok,
But could you clarify this statement you made?

"pumped fuel via my tanks hand pump as far as the fuel rail".

I ask because, if the "hand pump" is the primer bulb, I'm not sure that you should be able to push fuel to the rail doing it that way.

But, I suppose some fuel could sneak past the pump impeller since I believe it's a vane type pump and not positive displacement.

The low pressure system should only supply the VST reservoir and raise the float shutting off the Inlet valve. Like a carburetor works. That should stop the flow.
Then, the high pressure pump should pull the fuel from the reservoir and move it to the pressure regulator and injectors.

That's my theory anyway. But I'm still LESS than a rookie with these and trying to learn as we go.

It interests me because it might be a clue as to what is wrong.
 
jgmo said:
Ok,
But could you clarify this statement you made?

"pumped fuel via my tanks hand pump as far as the fuel rail".

I ask because, if the "hand pump" is the primer bulb, I'm not sure that you should be able to push fuel to the rail doing it that way.

But, I suppose some fuel could sneak past the pump impeller since I believe it's a vane type pump and not positive displacement.

The low pressure system should only supply the VST reservoir and raise the float shutting off the Inlet valve. Like a carburetor works. That should stop the flow.
Then, the high pressure pump should pull the fuel from the reservoir and move it to the pressure regulator and injectors.

That's my theory anyway. But I'm still LESS than a rookie with these and trying to learn as we go.

It interests me because it might be a clue as to what is wrong.
Click to expand...
Yes, sorry. Primer bulb is what I meant. Not sure how/why I'm able to manually push fuel that far. I wasn't finding any broken pieces of metal/plastic in the lines, so it must've just been able to flow past the pump
 
Regarding the belt, I didn't mean impossible. I meant darned unusual, and I should have mentioned "in my experience". I've messed with my share (100+?) of the mostly older 35-50 hp Honda's and have not had reason to replaced an idler or spring yet. Further, but not trying to beat a dead horse, if we all agreed on all points, this place would get boring quickly....

Regarding pushing fuel through the high pressure pump, I believe that will be possible IF the VST needle and seat are open. Otherwise, fuel flow will shut off right there assuming only it's functioning properly.

OP- The new EPA fuel hoses are known to collapse internally on occasion. Because you can push fuel through one with the primer bulb does not mean the pump will be able to SUCK fuel through it. I would be tempted to borrow another or bite the bullet and just replace it working on "easy stuff first" troubleshooting.....
 
Alan Hicks said:
Regarding the belt, I didn't mean impossible. I meant darned unusual, and I should have mentioned "in my experience". I've messed with my share (100+?) of the mostly older 35-50 hp Honda's and have not had reason to replaced an idler or spring yet. Further, but not trying to beat a dead horse, if we all agreed on all points, this place would get boring quickly....

Regarding pushing fuel through the high pressure pump, I believe that will be possible IF the VST needle and seat are open. Otherwise, fuel flow will shut off right there assuming only it's functioning properly.

OP- The new EPA fuel hoses are known to collapse internally on occasion. Because you can push fuel through one with the primer bulb does not mean the pump will be able to SUCK fuel through it. I would be tempted to borrow another or bite the bullet and just replace it working on "easy stuff first" troubleshooting.....
Click to expand...
I'll give it a try, thank you
 
Just a comment here, you cannot push fuel through the HP pump, if there is excess fuel in the vapour sep it will pour out the vent hose into the water.These engines don't have a water alarm, you haven't mentioned whether or not you physically removed the LP filter bowl to check for water???
 
iang6766 said:
Just a comment here, you cannot push fuel through the HP pump, if there is excess fuel in the vapour sep it will pour out the vent hose into the water.These engines don't have a water alarm, you haven't mentioned whether or not you physically removed the LP filter bowl to check for water???
Click to expand...
I was just thinking about pushing fuel trough the pump (dummy moment). In practice, the needle and seat are going to close well before the fuel level in the bowl gets to the point you are going to push fuel through the HP pump....
 
Hello, Has this issue been solved.
I’m having exactly the same issue with a 2006 BF225 with only 500 hours. I’m thinking it could be the ecm. Any thoughts?
 
2006 225's were renowned for main relay failures. If you don't know how to diagnose from the manual I suggest you get a pro. I've never had an ECU do this and a very expensive buy to see if it fixes.
 
Hi Bmbf,
I too would love to know if this issue has been resolved but I recommend that you open your own, new post.

The main reason is because this post is headlined as concerning a 50 hp. Because of that, someone that has a 225 hp and knows something that might help may just skip reading it.

You increase the possibility of someone helping you if you open a 225 hp headlined post and provide a detailed description of your problem.

Good luck.
 
Well, my own old post about possibly similar issue is there inactive since Sep 2021... (https://www.marineengine.com/boat-forum/threads/bf225-2003-malfunctioning.470517/)

I was just once again screening around old posts if I've missed some hints&tips&findings while running my BF225 still very fine with the 'temporary' direct HP pump power supply connection setup.

But yes you're right, I should have perhaps opened a new post to actively search for help... But you see on the other hand It's just that everything has been working great with the change for two seasons now and I must say I'm mad enough to actively forget that I'm supposed to bring the electrical connection back to original. I do recognize these kind of modifications includes risks, but so far I've not been explained perhaps what the risks exactly are ;)
 
Well, it sounds as if your "temporary" solution has had some success.

My old GranPappy always told me.....
....."Boy....you can argue about a lot of things.....
...... but you should NEVER try to argue with success"!
 
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