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BF225 Loss of power top end

R

rmorry

New member
I was having an issue with full power on my 2006 Honda 225 (380 hours, well maintained). At full throttle the engine would go to full RPM (and boat speed) for approximately 15 seconds before dropping about 1500 RPM and approximately a 10 mph reduction at which point it would stay there for maybe 30 seconds and the process would repeat itself.

I searched for solutions but didn't find anything specifically related on this site although I did find this forum very helpful while troubleshooting. I could not post due to an error trying to create an account which itself was resolved after contacting the administrator.

This problem started occurring shortly after I took fuel at my marinas fuel dock. I checked for water, replaced the low and high pressure fuel filter, drained the VST, checked the spark plugs and tested after each check but the same thing was happening. I was kind of leaning toward an issue with the VTEC system or ECU. Then it occurred to me that my fuel tank vents to my fuel fill. I remembered putting the fuel cap extra tight last time I took fuel to deter theft (or at least make it more difficult) so I loosened the fuel cap and tested again and the issue has been resolved. Back at full power now.

Has anyone here had a similar issue? Specifically the fuel tank would have to vent to the fuel fill and not all (or probably many) do. My boat is a Sea Chaser 2100 W/A Offshore Series and the fuel fill is Perko brand.

I did order a panel to enable checking of codes since I only had the 2 lights near the key but it hasn't arrived yet. On that note does anyone happen to know where that panel plugs in? Which connector? I expect to get that panel Monday so I will be installing then.

Am hoping if anyone had a similar issue that this post is somewhat helpful.
 
Ok, so basically the fuel tank vent and fuel filling plumbing are connected ,where by tightening the fuel filler cap there was no air entering to compensate the fuel draw.
Therefore the system had difficulty drawing enough fuel to the engine.
By loosening the cap all is good.
I knew someone who once taped the fuel vent outlet so as to stop fuel loss through evaporation.
The pressure in the tank from the vapors blew the fuel filler hose from the tank.
Most tanks I think vent to the outside.
Good to know thank you.
 
Heligeorge said:
Ok, so basically the fuel tank vent and fuel filling plumbing are connected ,where by tightening the fuel filler cap there was no air entering to compensate the fuel draw.
Therefore the system had difficulty drawing enough fuel to the engine.
By loosening the cap all is good.
I knew someone who once taped the fuel vent outlet so as to stop fuel loss through evaporation.
The pressure in the tank from the vapors blew the fuel filler hose from the tank.
Most tanks I think vent to the outside.
Good to know thank you.
Click to expand...


Yes. Exactly. Under high load at full throttle there must not have been enough air let in to draw the fuel required. It was a bit of a difficult diagnosis but an easy fix.
 
Also to let anyone know who may be wondering Perko does not make a lockable fuel cap for a vented fuel fill. The only option to deter theft with this type is an insert that has less than great reviews.
 
I am surprised that you do not have a separate and distinct vent in your fuel tank. I was under the impression that it is a requirement for all gas-powered boats with internal fuel tanks in the US, and it has been that way for decades.

Those vents do tend to get clogged by wasps and other critters, so part of my spring procedure is to make sure it is clear by running a piece large monofilament line down it into the tank.
 
This is the fuel fill. https://perko.com/catalog/fuel_syst...ht_neck_vented_fill_for_1-1_2"_hose_marinium/

The larger connection is for the line going to the tank for filling. The smaller connection is for the vent from the tank.

I am not aware of any other separate vent. If there was the problem I was having shouldn't have occurred. I am very surprised that caused the issue but it was clearly resolved as soon as I loosened the fuel fill cap after about a week of diagnosing. Was really expecting a costly fix for this but it only cost me the price of 2 new fuel filters....and my time.
 
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