1996 BF-75 Fuel Pump??

I noticed that I was making some oil when putting the boat away for the season. It was about 1/4" above the full line. It was suggested that the most likely culprit was the seal for the fuel pump. Would that make sense and, if so, can the O ring seal be replaced or does the entire fuel pump assembly need replacing? It seems there are two pumps on the BF-75. It appears to be an easy job to replace either. Is that true?

I can help. I just removed two fuel pumps from a 1997 90HP, which is the same as a 75.

The fuel pump would push fuel into the cylinder head. Change your oil, put the oil in a glass jar and see if the fuel separates. If it does see if the liquid is water or fuel. This is big!

The fuel pump o ring keeps the engine oil from leaking out of the cylinder head. O-rings are $3.

If the pump goes bad it pukes gas into the head.

EZ replacement. $70 each. Do both.......IF that's your problem.

Thanks. I don't see any oil residue around the pumps so I am assuming it is not the seals. Unfortunately I changed the oil after seeing the overfill and mixed the old oil in my 5 gallon waste oil container. I was also asked if I smelled gas on dipstick but after the fact. Can you tell me what is happening as a pump goes bad. The engine runs great. Will the failure be slow so I can check the oil more thoroughly in the spring or is it like a 95% chance it is the pump and being a 1996 model I should just go ahead and make the change? Where did you buy the fuel pumps?

Buy your parts thorough this site to support it.

If changing them will ease your mind just do it. It's cheap and EZ, like a good date!

Mike said to test pumps, remove the bolts holding pump in. Leave fuel hoses connected, pump the heck out of the fuel primer ball and see if pump leaks fuel out the back.

Thanks for the tip about testing the fuel pumps. Good info. I certainly don't mind buying parts on this site but when it comes to Honda their offerings are limited mostly to accessories like thermostats or multiple fuel fittings.

One other cause for "making oil" is stuck thermostats. If the engine always operates at too cold temperature it will cause poor combustion with the resultant gasoline vapor forced into the crankcase. Some of the vapor will condense and elevate the oil level. Running at below nominal temp also causes excessive carbon deposits to form in the combustion chamber and will exacerbate wear and poor performance.

Just sayin'.

If parts are unavailable here, use boats.net. Good HONDA selection at reasonable prices.

Thanks again. So how would one check for a stuck thermostat? Can temperature be measured at the pee hole when hot? I am guessing that fuel pump seals cause more issues than thermostats.

A good question.

One way would be to hold your hand on the bypass tube (item 14 in the parts page link) as the engine runs and begins to heat up. If the thermostat is operating correctly, there will be a point when, as the thermostat begins to open, the temperature of that tube will suddenly change.

A better method, that would yield more useful info, would be to use an infrared temp gun aimed at the cylinder head where the thermostat is located. The head should rapidly get hotter and hotter and then the temperature will go down a bit and back up a bit in what is called "modulation" as the thermostat opens and closes to maintain a constant operating temp. You would expect this "stabilization" to take place at around 160f to 170f if all is well. If it is a bit higher or lower than that, it's nothing to be concerned about. Heat transfer to the surface of the metal for the gun to read will vary greatly depending on several factors including what the water make up is.

The important thing here is that the head temperature goes up pretty fast from a dead cold start and then stabilizes as the stat begins to work. If the head temp goes up slow and gradual and never reaches a point over about 145f to 150f then your thermostat is most likely stuck partial open and the engine won't burn it's fuel properly.

Of course, if the temp goes significantly OVER 170f then you may have a stat that is not opening fully and you may experience overheat as the engine is worked harder.

http://www.boats.net/parts/search/H.../BF75 LA/INLET MANIFOLD THERMOSTAT/parts.html

As far as fuel pumps causing more fuel contamination than thermostats, MY experience has been just the opposite. I have seen more "making of oil" due to faulty stats than due to leaking pumps. It's why I mentioned it on this thread.

Typically a leaking pump will cause the oil to rise rapidly after an oil change as opposed to a stuck stat causing a very gradual rise between oil changes.

Neither is good for the engine and each should be eliminated as a possibility before further operation.

Good luck.

Well professor Jimmy, I liked your dissertation. But I'm just al old country bumpkin - the way I test it is to remove it. They usually stick in the open position, so it will be obvious if they are. On the other hand, if they are closed like they are supposed to be, I stick them and a pot of water and start heating it up on a propane burner and use an instant thermometer. It will start to open at 140 F and should be fully opened at 160 F. It only opens about 3 mm if I recall correctly.

Well, I was thinking he wanted to do a quick check that was "non invasive".

To ACCURATLY test the opening of a thermostat "on the stove" I do two things:

First, push the stat flange open and trap a brightly colored piece of thread in the opening. Then, SUSPEND the thermostat above the bottom of the container. This prevents direct heat transfer from the burner skewing the results. Then, as the stat begins to open, it is easy to see because the thread will float out of the "jaws" of the flange.

This is the Detroit Diesel method given in their service manuals.

Jimmy - good procedure. I forgot to mention that I do suspend the t-stat in the hot water, using a paint stirrer and a string, but I like your method better.

As for removing the t-stat, I always think it's a good idea to do it often in order to assess whether there is any junk or corrosion accumulated in that area.

Well, as usual, I can't argue with you chswk_man. Yours is probably the best approach there is for maintainig a reliably operating cooling
system. And, those that have been maintaining outboards for a time know that the thermostat housing is where corrosion and trouble are CONSTANLY brewing.

I do have a question though. Does your 225 specify 140f stats? That seems VERY low for an EFI engine to me.

Jimmy, I'm doing this from recollection, but I'm fairly sure the BF 225 t-stats start to open at 140F and are fully open at 160F. When I get a few minutes of spare time, I'll look it up unless someone else jumps in with a confirmation or different opinion.

OK - looked it up. Start opening at 60C (140F) fully open at 70C (158F). Page 3-9 Helm shop manual. OK, so I was off 2 degrees on the high end. Beat me with a wet noodle.

The 225 runs cooler than the older BF75's. The stat on the BF75A starts opening at 72C/162 F and is fully open at 82C/180 F.

Mike

Well. ...if I would have had to bet something substantial on it, I'd be DEAD BROKE! My background in truck and automotive engines has always tended toward "run the engine hotter and burn the fuel more efficiently" along with less carbon build up.

Almost sounds as if Honda may have had a cooling issue with that block and head arrangement. Got any thoughts about that? No big deal bur I'm always curious about this stuff.

Also, getting back to JackB1's outboard....am I wrong about what it is? I didn't find reference to a 75 hp so I just assumed it is a 7.5 hp. But I'm sensing I'm the only one that thinks it is a small twin. Please enlighten me if you will.

Thanks

Thanks.

75 HP. I did not think much about it, since after the second post, Hairdresser assumed it was a 75..."same as a 90 HP"....so I assumed the same.

Now that I look closer, one bit of additional info.....the 7.5 was only made through 1985....this is a 1996.

The new 75/90's have two different thermostats. One is the block and one (which is cooler) in the head.

Mike

Ok, that makes sense. I am at a disadvantage looking at this stuff since I don't have an "in" with Honda anymore. I looked on boats.net and they don't reference a 75hp until 1998 so I assumed it was the little one. One other piece of info I was missing was that I didn't realize they stopped the 7.5 that early....but I should have known.
Thanks Mike.

OK, now that it is Spring I am bringing this thread back after doing some investigating and with some questions. I removed both fuel pumps and pumped up bulb hard with no fuel leakage evident. My next thought was to remove and check thermostat but I noticed the gasket and thought I had better check about parts before fooling around with it. I can't seem to find a thermostat listed anywhere on the internet for my model which is a 1996 BF75A [BBAL whatever that means?] and SN 1000367. Apparently made in Japan. Can someone give me a heads up on this motor and where parts can be found? I know it is a Honda Civic engine turned on its side and that a Civic oil filter fits. Would a Civic thermostat also fit? I also don't know how to find the thermostat part number. Any help would be appreciated.

Here is a link to the parts for your motor. The 1996 and 1997 were BF75AT models. So, the parts are the same. Click on the thermostat link and it will give you the correct part numbers. I would not assume that it is the same thermostat as the Honda Civic. It may be, but go by the part numbers in the link and you can not go wrong. http://www.boats.net/parts/search/Honda/Outboard Engine/1997/BF90AT LRTA/parts.html


Sorry, I took so long answering this. I have video problems on my laptop at home with all my Honda programs.

Mike

Thanks for the reply. What was confusing was that in "year selection" one of the options is "pre 1997". When going to that section however they leave out 75 an 90 HP in the models listed. Can I assume for any part I need that the 97 listings would be accurate? I believe depending on serial number some models used a Mercury lower unit. Thanks again.

You should be good for 1996 and 1997. Both years used the Mercury gearcase.

Mike