Honda BF75D/BF90D Fuel System Troubleshooting and Maintenance 

Glad to help 😁

Thanks Abel - glad to help.

Absolutely- glad to help!

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Awesome - glad it helped 😁

Hey Jerry - What type of maintenance are you trying to do - are you trying to drain fuel from something on the motor? Also what type of manual are you using - is it the owners manual?

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Thanks - glad to help

Glad it helped!

Yeah ethanol based fuel is horrible on these motors especially if the are sitting.

Thank you!!

Hey Brian - yes mostly salt water in Florida.

Thanks!

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Glad to help 😁

Hey Ron - yeah sorry I can’t help with the carb motors. If you’ve eliminated everything on the boat side (tank, hoses, connectors, filter, gas type) then I would definitely say it’s something on the motor. Does it run rough at higher speeds or just idle? The tough part is, fuel issues often doesn’t produce codes to point where the problem is. So if your current shop is just looking for codes, then they might miss some things. Might want to get a second opinion from another shop - I learned this lesson the long hard way 😬.

Link to the manual and parts are in the description box

Yeah not everyone knows there are 2 filters

Hey Roger - well I can think of a few things. First option is to disconnect the hose before the external separator and siphon it out from there. Second option is to pump it out by hand with the bulb by disconnecting the low pressure hose after the LP fuel filter then connect a longer hose to dump fuel into and external gas can. Third option is to simply run it out with the motor. The fuel is probably fine if it’s non-ethanol with stabilizer. Fourth option is to have a marine shop do it for you. Good luck.

Thanks Dave. Ended up disconnecting at the external water separator and was able to siphon off the gas. Thanks for the suggestion. I just have to figure out what to do with old gasoline.

Good deal

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Glad it helped

Might be two separate issues if you’re having temp and fuel issues. Check out my other video for troubleshooting the cooling system. As far as the fuel issues, make sure to check/change out all the basic stuff first before digging into the VST. And don’t change your fuel injectors until after you are certain your VST is clean otherwise you will clog up your new injectors.

I have many of the part numbers listed on the video description area. I get most of my parts from www.boats.net/catalog/honda/outboard

Yes - the 75s and 90s are essentially the same motors. And yes boats are expensive, but just think how much you are saving doing it yourself 😁.

@@davecavanaugh66 Let me get this right: If the fuel strainer is cruddy it's because the pump and VST have crud in them? In other words the fuel flow is such that the strainer is the last stop before the injectors?

@@BegoneJonah - yes in my experience if the HP fuel filter is dirty, then I would definitely look upstream for other issues.

@@davecavanaugh66 ...and you have to remove the lower plastic half of the cover, to get the VST out, right?

@@BegoneJonah yes you have to remove the cowlings. I have another video that shows how to do that.

Good deal. Yeah I tried cleaning my injectors, but I decided just to replace them considering all the mess in my VST and filter - just didn’t want to play the guessing game.

@@davecavanaugh66 may do the same. 80 bucks or so a piece. I have done major work on motorcycles and used to be a place that blueprinted injectors but likely cost more than buying new.

Hey Brett - the parts for 75 and the 90 are the same. All are listed in the video description area. Not sure exactly what filter or hose you are talking about (high pressure, low pressure, or water separator). Maybe you can tell me which part of the video I show that in (minutes).

@@davecavanaugh66 thanks. The i saw the correct hose place in the video. It comes out as soon as the water water separator is pulled off. It tucks back in the frame at the very front of the motor.

9:45 , there's a hose almost blocking removal of the filter

@@brettbw1 ah yes that’s just a vent hose.

Interesting issue - I order my parts off Boats.Net - I believe they ship overseas to certain countries. You should probably call them +1-863-354-6377. As far as the diagnostic tool, having one is definitely handy but not 100% necessary. I use Healtech OBD-H01 Diagnostics Kit. You will need to also contact them to see where you can buy for your area.www.healtech-electronics.com/wheretobuy

Dave Many thanks for your Quick respons👍😊

Is this motor new to you or have you had it for a while? Other than the buzzer, are there any indicator lights? Does it overheat?

Hi Dave, thanks so much for your reply! We got the motor lightly used about 3 years ago. Everything seems to be running good, lots of tell-tale, oil's good etc. I replaced the thermostat and the temp sensor thinking that was the problem, but no cigar.. I've tried all the regular methods for pulling the codes, -shorting out the red plug etc. but that doesn't seem to work... We totally depend on our boats up here on the wild and remote BC Central Coast, -we have water access only to our house.. @@davecavanaugh66

Yeah it’s pretty snug in there because it has a plastic skirt around the pump, plus there is a nipple at the bottom. In my case I had a new one so I wasn’t worried about damaging it. Can’t remember for sure, but I think I grabbed it with some needle nose vice grips.

You're welcome!

All the parts are listed in the description section with link to boats.net

Well that could be a ton of things. Why do you think it’s fuel related? Have you checked for spark?

@@davecavanaugh66 There is no fuel discharged from the vst and HP pump.

@@stansronuc3934 the BF60A may be different than the BF75/90D, but I take it you pulled the injector rail hose and tried to see if you get a 2 second pump of fuel when you turn the ignition?

@@stansronuc3934 looking at the owners manual for BF60A and it looks like there is a 10 amp fuse for the HP fuel pump. Did you check that? cdn.powerequipment.honda.com/marine/pdf/manuals/00X31ZZ36100.pdf

@@davecavanaugh66 Thanks Dave, I will check the fuse. Thank you for the link.

Good question - most onboard fuel/water separators provide filtration as well as separation capability. Of course you probably could get away with not having one, but my opinion is it’s a good practice. That said, I have seen lots of smaller portable motors 30hp and below don’t have them onboard.

@@davecavanaugh66 I just bought a pontoon with a 2006 BF50 and it has the onboard filter but I am ordering a Racor 120R-Rac-01 filter, couldn't hurt. Thanks Dave

Yes the bulb should prime the system all the way to the VST. Once the VST is full, the float valve will close and stop the flow of fuel and your bulb should get hard. If your bulb is not getting hard then you have leak or air is in the line. The video shows how to bleed the line.

When you say it won’t start - does it beep twice when you turn the key? Do you get the 2 second pump from the High Pressure fuel pump? Does the motor turn over?

Sounds to me like clogging in the VsT and/or a high pressure fuel pump issue.

Hey Brett - I show what I use in this video. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-vqTWTTE3ag8.html

Yes - another dealer can do it.

I can think of several things, but first let’s start with the basics. Can you get the motor to rev up to 3-4k rpms when not in gear as a test to ensure the gauge is not bad?

Are you saying the motor runs fine but will not go over 4300 RPM?

@@davecavanaugh66 YES!!!

@@davecavanaugh66 And the engine is Honda bf80A.

@@tanja5261 so not sure about a Honda BF80A but max RPM is generally about 6000 RPM. If you are running the motor in a bucket or on a hose, without the prop engaged, then that’s what you should see. If you are on the water with the motor in gear running wide open, then it could be your prop size that is causing RPMs to be low. There are lots of variables to consider when it comes to props. Watch my prop video.

@@davecavanaugh66 Thank you for your answer! I have allready change my prop from Steel prop to aluminium prop. And it is a right size prop. Could it be somekind of electrical problem? Like a bad battery or wires. I'm getting out of options...

Not sure I can provide more help beyond what’s in the video.

Hi Gary - Intermittent issues like that are hard to troubleshoot. Can you duplicate the issue when you are at home running on the hose? Next time that happens, first thing I would do is check the water separator bulb on the motor to see if it has fuel in it which might be an indicator that the LP fuel pump is having issues pulling fuel from the boat. If that’s the case, then it could be the LP pump or it could be an indicator that’s something on the boat side. My other thought is the VST float might be having an issue (sticking closed) which would cause the VST to dry up and not stay full. If you just had the HP fuel pump replaced, then something that may have gotten messed up in the repair. Was this issue happening before you had the HP fuel pump replaced? Also have you done testing on the LP and HP pumps like I showed in the video?

Sorry so long. Hey we didn't get a chance to run the boat prior to doing repair and maintenance. A little history to catch you up. It had sat for almost 2 years during the pandemic. When we purchased the boat had 410 hours if that is correct. Other than running for just a few minutes without a load. That was it. Due to sitting we wanted to clean out or replace the whole fuel system. That's how we got into the vst HP pump. It was similar to your HP pump. Very dirt. However the tank was clean. All the fuel line, primer bulb, filters, oil, impeller pump and spark plugs. Really any regular maintenance. We did it. We are unable to duplicate at the house on a hose. Never does it at idle. Only when we are running did we see the issue of not full primer bulb. Which led us to the LP pump. I did replace LP pump yesterday. It did not stall. Primer bulb stayed firm. Not saying that fixed the problem. Think it has to help. Our old LP pump was the original. The hoses had to be flipped. Being it hasn't totally failed. I think it was just a weak fuel flow from the tank. Where we are at now. We have noticed the rpm will not go above 3000 rpm. Read several opinions on different reasons and parts that may be failing. Fuel injectors, neutral safety switch and possibly running hot to name a few. Our boat is a 2008 Sea Fox 187 CC with a Bf90d. It will run 35 mph at full throttle with our family of 4. Does that sound normal? Is something keeping it from going above. Does your rpm go above 3000? I have a plug in code reader. That flashes the light. No codes are flashing. If I purchase Dr H would that tell me anything. Sorry its a lot of questions. Gary

@@garymartin8316 so are you saying you can run 35mph at 3000rpms? Has it always run like that or is this a new issue. To me it sounds like you have more than one issue.

@@davecavanaugh66 Since we have owned it always ran like this. . Top speed is 35mph at 3000 rpm. The PO told me his top speed was around 33 mph at 3000 rpm also. Could there be a rev limit? Guess tach could be sticking at 3000 rpm. What rpm does your motor read at top speed?

@@garymartin8316 that’s a prop thing. Check out my prop video. You should max out between 5000-6000 rpm to maximize performance.

Thanks for the feedback

If no fuel is getting fuel to the rail? Then work backwards.

So that’s a loaded question because it could be lots of things. My guess is it’s a fuel related problem. Did you eliminate all the basics such as good fuel, good fuel flow, good hoses, good bulb, clean filters, clean water separator, air vent on the tank? Is you motor fuel injected or carbs?

@@davecavanaugh66 fuel injected. new plugs, new fuel filter. What is Bulb?

@@robertdickens6531 the fuel line bulb connected to the gas tank that you squeeze to manually pump gas into the motor. Sometimes the lines and the bulb valve cause issues restricting fuel. I show all this in the video. Is your fuel tank built in or portable tanks? Did you change both fuel filters - high and low pressure? Again, I show all this in the video.

Interesting - I haven’t had any issues with them - still flexible and no break down yet. I will keep an eye out in my filters.

All the info I have seen was from the use of ethanol fuel, I saw this in the fuel lines in my Hewes Craft so swapped them out. Great videos, thanks for your time and effort.

@@virgilblanton glad to help. Good point and that makes sense with ethanol based fuels breaking down hoses among other things. Yet another reason to stay away from it.

I totally agree about that fuel, but our current government is making non ethanol gas like 4.30 here in northern Idaho. And my boat tank is 40 gal, sad for sure! Take care Dave!

Interesting issue - could be several things. Does it only surge when you are under power? If so, what does the Tachometer read when it’s surging? Does it surge when you are at idle too?

@@davecavanaugh66 The problem is solved. I attached a clear tube to the float housing as suggested here. When the engine started to rev, I stopped it and opened the drain plug in the float housing. By then the floating house was almost empty. When I then started the engine at idle, the level rose slowly. At first thought it was the feed pump, but it turned out there was still air in the system after the water separator/filter was changed a few days ago. the conclusion is to get all the air out by pumping on the hand pump while the engine is running, until all the air is out.

@@rs4912 interesting- the VST does have a breather hose on the top that should allow air out. So I’m guessing your air in the line was on the low pressure side?

@@davecavanaugh66 That is correct. So there was no fault with components on the engine, only air was the problem. But anyway, a very good video you have made that you can follow the entire petrol system from tank to injection👍

@@rs4912 thanks - glad it helped 😁

publications.powerequipment.honda.com/details/61ZY900E3-BUNDLE

Didn’t have one and wouldn’t know what normal pressure is supposed to be. The shop that I took it to should have used one but obviously they didn’t know what they were doing. So I did the best I could with what I had. Just good old fashioned troubleshooting. Still would have had to clean the VST in the end and I learned a ton along the way, so I say that’s a win 😁.

@@davecavanaugh66 for sure it's a win. I only say you could save time. But maybe with less fun. You have the shop manual, with is beautiful to read and in there you can find really everything. Have fun with your fantastic outboard.

All the part numbers for BF75D/BF90D are provided in the description area. Also show this in the video.

OEM Part Number: 16450-ZY9-003

Would u know where I can order one off internet , and I thank you so much !!!

Boats.net

Thanks alot !!!

Triumph 1700 Skiff (closer to 18ft)

@@davecavanaugh66 I have a 87 Robalo 18 foot with that motor don’t seam big enough for mine

@@76whalen my boat weighs about 2800lbs with 2 men, fuel, gear, etc. On a good day, I get about 32mph top end speed at about 5300 rpm using a 4 blade stainless prop with a 13” diameter / 17” pitch. I also added smart trim tabs which helps lift the stern. It took a lot of trial and error (and money) to figure out how to maximize performance on my boat based on what I use it for which is mainly shallow water flats fishing in Florida. My point is there is a lot that goes into dialing in the right prop/trim setup depending on all the variables I mentioned above.

@@davecavanaugh66 mine will turn up about 7000rpms. With a 13” 15 pitch. Three blade. I just ordered me a four blade 13” 15 pitch. Hope it planes off quicker. And slow the rpm’s down a bit

@@76whalen yeah 7000 is way over. Book says 5300-6300 rpm. The 15 pitch put me at 6300 and the 17 pitch put me at 5300. There was really top end performance gain with the 15, so I elected to go with the 17.

I’m not a marine mechanic, but I can’t try to assist. Please record what’s it’s doing and post a link here.

Thanks - glad to help!