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Honda BF50D Surging problem

S

stedee

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Hello, I have a 2011 Honda outboard BF50D on a 18' pontoon. To describe the concern: running at RPM's above 3,000 it will soon begin to surge as if it is running out of fuel. I have to back off throttle and allow it to idle when this happens. It does not stall when this happens, and it will recover and run as it should if I keep the RPM's below 3,000. I have a factory service manual but not much experience in the marine field. I recently replaced the separator filter and the high speed filter. pretty sure water is not an issue. When I replaced filters, I drained some fuel out of the vapor separator and it was clean. Have no idea how many hours are on this motor. There is a Honda gauge in dash that shows a mil symbol that comes on and goes off (seems as if it is working correctly). Have not tried to pull any codes yet. When the problem is happening, no mil light on. I have noticed the primer bulb is very hard to squeeze, if at all, even after overnight (not sure about that). It seems as if it is not getting the volume of fuel it needs to run. Any ideas?
Thanks, stedee
 
Have you, or anyone else had the seperater apart? I ask as quite a few have had some trouble with a grommet that's used at the top of the fuel pump. If not installed correctly, it bunches up and blocks/partially blocks fuel pump output. It's natural to install this grommet into the top of the seperator, then push the pump into it securely. This is almost guaranteed to cause a problem like yours. The proper way to install is to slide the grommet on to the fuel pump, then install that into the seperator body. See part # 28 here:
https://www.boats.net/catalog/honda...-bbej-1300001-to-bbej-1399999/vapor-separator
 
Alan Hicks said:
Have you, or anyone else had the seperater apart? I ask as quite a few have had some trouble with a grommet that's used at the top of the fuel pump. If not installed correctly, it bunches up and blocks/partially blocks fuel pump output. It's natural to install this grommet into the top of the seperator, then push the pump into it securely. This is almost guaranteed to cause a problem like yours. The proper way to install is to slide the grommet on to the fuel pump, then install that into the seperator body. See part # 28 here:
https://www.boats.net/catalog/honda...-bbej-1300001-to-bbej-1399999/vapor-separator
Click to expand...

Alan, I bought the boat/motor last fall, ran it a dozen times or so. This year have had it out several times with no concerns until a few weeks ago. I have not had the separator off yet, but have been looking at the system in the factory service manual. I was hoping it was the high pressure filter needing replaced, but not so. OK with replacing it because of recommended service interval. Pricey little filter though. I need to go over base engine and check/adjust according to maintenance schedule. I have no idea how many hours or what has been done to it. Plan to check plugs, valve adjustment, and timing belt as part of normal maintenance. However, this symptom sure makes me think it is a lack of fuel at heavy load. Thinking about looking inside of the supply fuel hose that contains the squeeze bulb to see if anything could be blocking flow. I have not seen any sediment in the water separator bowl, but the bulb is very hard to compress. We have planned a weekend boating getaway at the end of the month and I don't want to pull and disassemble the vapor separator yet, for fear of needing o-rings or something to put it back together. I have looked and understand your post, and want to thank you for responding! Will keep this thread going until I find the problem. stedee
 
Alan Hicks said:
Have you, or anyone else had the seperater apart? I ask as quite a few have had some trouble with a grommet that's used at the top of the fuel pump. If not installed correctly, it bunches up and blocks/partially blocks fuel pump output. It's natural to install this grommet into the top of the seperator, then push the pump into it securely. This is almost guaranteed to cause a problem like yours. The proper way to install is to slide the grommet on to the fuel pump, then install that into the seperator body. See part # 28 here:
https://www.boats.net/catalog/honda...-bbej-1300001-to-bbej-1399999/vapor-separator
Click to expand...

Alan, I bought the boat/motor last fall, ran it a dozen times or so. This year have had it out several times with no concerns until a few weeks ago. I have not had the separator off yet, but have been looking at the system in the factory service manual. I was hoping it was the high pressure filter needing replaced, but not so. OK with replacing it because of recommended service interval. Pricey little filter though. I need to go over base engine and check/adjust according to maintenance schedule. I have no idea how many hours or what has been done to it. Plan to check plugs, valve adjustment, and timing belt as part of normal maintenance. However, this symptom sure makes me think it is a lack of fuel at heavy load. Thinking about looking inside of the supply fuel hose that contains the squeeze bulb to see if anything could be blocking flow. I have not seen any sediment in the water separator bowl, but the bulb is very hard to compress. We have planned a weekend boating getaway at the end of the month and I don't want to pull and disassemble the vapor separator yet, for fear of needing o-rings or something to put it back together. I have looked and understand your post, and want to thank you for responding! Will keep this thread going until I find the problem. stedee
 
NSDON said:
Old fuel line breaking down and clogging flow? Get new line and bulb, if not done recently.
Click to expand...

NSDON, Thanks for responding. I am suspect of a restriction here because of how hard it is to squeeze the bulb. Going to take a closer look, maybe try to disassemble it if I can, to see if there is anything inside that could be blocking flow. It is probably as old as the boat- 10 years. stedee
 
Not sure what makes that high pressure filter so expensive. If I were to find one comparable, I'd be scared of it for fear that the pump would blow the filter media apart.

The fuel pump should come on and run for a second when you turn the key on. If the fuel were directed into a container so you could see what's happening when that pump is running (maybe disconnect the line at the fuel rail?), you might try turning the key on while watching to see what kind of flow you're getting. If it's a dribble, you know you're problem is at the filter or somewhere inside the vapor seperater.

Regarding that fuel line, you may not be able to locate a restriction. Maybe remove the low pressure filter and see how difficult it is to use the primer bulb knowing there's no restriction on the motor end? -Al
 
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Stedee,

Good suggestions provided to you so far and I completely agree with you about going over the base engine... ie: timing, valve adjustment etc.

That rock hard primer might indeed be a clue and checking/replacement is a top-o-the-list item for sure.

Just want to point out that the MAP sensor is the primary load sensing device for the engine and is really easy to check with a hand vacuum pump and a multimeter. The specifics should be in your shop manual.

Good luck.
 
jgmo said:
Stedee,

Good suggestions provided to you so far and I completely agree with you about going over the base engine... ie: timing, valve adjustment etc.

That rock hard primer might indeed be a clue and checking/replacement is a top-o-the-list item for sure.

Just want to point out that the MAP sensor is the primary load sensing device for the engine and is really easy to check with a hand vacuum pump and a multimeter. The specifics should be in your shop manual.

Good luck.
Click to expand...
JGMO, Thanks for responding! I did spend a little time checking a couple of things today. Pulled all the plugs, looked good, gaps in spec, reinstall. Removed fuel hose at quick connect on motor. Held check in and squeezed bulb. Lots of fuel, did this 4-5 times. Went to separator, removed bowl, squeezed bulb and again, lots of flow there. Next, unbolted low pressure pump and checked plunger, seemed to work smooth, reinstall. Checked hoses and found vacuum hose for pressure regulator was just barely on the intake fitting. Not sure if there was a vacuum loss there, but reinstalled hose fully. Will take and run boat tomorrow. After doing all those checks, and just reading your response, I'm wondering if the MAP is faulty. I have replaced map sensors on motorcycles. My experience with valve adjustments on powersports engines is that they stay in spec for a long time, usually longer than the recommended service intervals. But I will check these since I have no idea how much time is on this motor. Fuel or electrical.......
Thanks, stedee
 
Fixed!!!
Yes, had the boat out on the water this afternoon, ran great. Vacuum hose from fuel pressure regulator was just laying against fitting on intake manifold. It appeared to be in place until I touched it and it moved away. Thanks to all who chimed in and offered their time and help! Important lesson, check the basics including vacuum hoses.
stedee
 
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