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Having problems with my 2012 fuel injected bf50D

J

Jayrudy

New member
Hi Newbie here having some trouble with my honda its a 2012 fuel injected bf50D it was a tiller when i got it and and had the dealer make it remote steering. So rite now iv been having problems for past 4 weekends where the motor would struggle an wouldn't go past 3800 or 4200 rpm . I have bypassed the fuel/water separator bypassed the main fuel line iv changed the primer ball changed the spark plugs ran it with the gas cap almost off to make sure it was getting air . I had a mechanic come look at it he checked the pressure on the high pressure fuel pump that was good he said he did find that a high pressure fuel strainer witch is the size of a quarter was black and gritty i called him back to put it back in and he never called me back so i put it in myself Took for a spin seemed fine but would only go up to 4600 to 4800rpm and not the normal 5000 rpm but it did not sputter so i thought it was good next day drove for 3-4 hrs Fishing in bay seemed fine did have 3 people on boat and it wouldnt get on plane would only go 3500 rpm but never sputtered than when i dropped my guest's off i could get back on plane and up to 5000rpm But the very next day took 2 people and some gear to little island came back took3 more ppl over and me and 1 person went to drop crab traps and it started puttering out at 4000 rpm and you had to keep it under that so my cousin said try to bypass fuel water separator an hose line so hose comes out of motor the primer ball than tank I ran it with me and 1 person for 10 min it went to 5,000 rpm seemed fine thought it was fuel line or fuel water separator but than 30 min later me an another person went out and it would start to putter our at like 3600 rpm The next day took out for 20 min ride by myself ran fine but would max out at 4600 to 4800rpm And took it out 2 more times and it did same thing Its so frustrating. I do feel like i hear an air noise but the mechanic said well you probably never recognized it because motor was fine but idk My cousin said mite be numeral saftey switch on motor starting to go bad so this weekend ill try that . I took video at dock of where i hear the loud air sound i sprayed some gum cleaner in it and it putterd than put in neutral and gave a lil gas not much but you can hear the air not sure if its normal or not. The motor only has 200 hrs on it . In march the shop put it on the machine and gave me print out of hrs and there has never been any codes on it either. but any other help in direction would be greatly appreciated Thank you
 
Did you fit a new high pressure filter or did you put the old one back.They should be replaced every 200hrs and they cause this very problem when blocked.The hissing noise is normal, that is air being drawn through the idle air control valve
 
iang6766 said:
Did you fit a new high pressure filter or did you put the old one back.They should be replaced every 200hrs and they cause this very problem when blocked.The hissing noise is normal, that is air being drawn through the idle air control valve
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Yes i put a new one in and changed the gasket as well . Friday im going to see if injectors are spraying rite. I know there is a 3rd filter that is very hard to change im wondering if i should take it to mechanic to have that one changed but my guy said no shouldnt be clogged i think its connected to the high pressure fuel pump .
 
Better just order the original from Yumbo Parts Japan. I've had one where the owner did similar and fried the fuel pump driver in the ecm.Just saying
 
iang6766 said:
Better just order the original from Yumbo Parts Japan. I've had one where the owner did similar and fried the fuel pump driver in the ecm.Just saying
Click to expand...
Fair point, and a genuine pump is indeed the cleanest fix — it's in the Notes of my write-up.


But the fried-driver case you saw was almost certainly a relay installed without the flyback diode (or wired so the pump current still ran through the ECM). An unprotected relay coil kicks back hundreds of volts into the FFP transistor on every turn-off — that will eventually kill it. That's exactly why the diode across the coil is a mandatory part of this mod, not optional.


With the diode it's the opposite: the ECM driver only sees a 117 mA load instead of the 1.7–5 A pump motor it was switching from the factory — far less stress on the FFP transistor than stock. Honda does the same thing themselves: every factory relay on this engine (main relay, power tilt relay) has built-in coil diodes, as shown on the TM035 diagram.


We have fully tested this setup — the engine runs flawlessly, priming is stock, the pump shuts off with the key/ECM exactly like factory.


One more important point: a genuine pump is not always a guaranteed fix either. Even brand-new OEM pumps sometimes show the same behavior — in the "2015 bf50 SFI not getting fuel" thread on this very forum, the owner installed a factory pump and the engine still fired up and died the same way. The relay + diode setup closes the problem completely in every case: the ECM never sees the pump current at all — aftermarket, OEM, or an aging pump with rising draw.


Official Honda wiring diagram (TM035): http://cdn.powerequipment.honda.com/pe/pdf/pubs/tm035pdf.pdf
 
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