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BF 75 Oil Pump

JackB1

Member
While out boating today the oil light went on and engine went into low RPM mode. Thought it was low oil but found that was not the case. Someone has suggested it may be the oil pump. This is a 1997 Honda BF-75. Engine hours are relatively low despite the age. Is the oil pump the most likely culprit or should we look for something else first? Is replacing it a job for the DIY mechanic or best left to a pro? Appreciate any suggestions.
 
I would want to make sure it's the pump before entertaining ideas of replacing it. In my experience (mostly mid size Honda's) they aren't hard on oil pumps. My first move would be to have a look at the wire connection on the oil pressure sending unit. Any corrosion there could be the source of your headache.
 
I have a few of these older Honda motors.----As far as I know when the motor has oil pressure the green light should be ON and shining brightly !
 
As Racerone says, oil light should be on whilst engine is running, perhaps you have an overheat which would explain the limp mode?
 
I agree with the other guys. You need to properly diagnose what happened before considering doing anything major on your engine.

If you've never had a green oil lamp on while your engine is running that might be something you need to look into. Hondas typically always show a bright green light on when oil pressure is good. But it's possible that someone used a non Honda dash panel?

Was the warning light you saw red? Was that light labled "oil pressure"?
As has already been pointed out, it might actually be an overheat warning.

Think about those things and get back to us with what you find.

Good luck.
 
My bad. Long day yesterday. That green light should be on when the engine is running. I read the original post incorrectly (I was thinking the green light had gone out). Sorry for any confusion.

Engine may have just dropped a cylinder causing it to loose power, or one of a dozen other things.

My question would be when first fired, is it still in "limp mode"?
 
We wait patiently for Jack B1 to tell us more.----Trouble shooting wins out over --" someone has suggested " ---each and every time !!
 
I really appreciate the help. We are working on it but somewhat difficult. I am in Maryland and boat is now in Delaware although only a 20 minute ride away BUT due to virus restrictions keeps me at home. Boat was given to Grandson [college freshman] who may be joining the forum shortly. The first thing he is going to do is put a continuity tester on the oil pressure switch and test as per Honda service manual. One probe on switch body and second on middle wire connecting point with wire removed. Assume that s done with engine off?? I kept boat and motor pretty much in pristine condition but we do deal with saltwater leading to potential corrosion and it is a 1997. I had a suggestion of a clogged pick up screen but even though the boat had set for a while the oil still was amber colored and clean so doubt that would be the answer. Hopefully other questions above will be answered by new forum member and boat owner shortly. Thanks again all.
 
To test the switch, yes, you FIRST check it with the power wire removed and wire terminal taped or somehow prevented from going to ground. Ohmmeter should show infinite resistance in this "state" as it is "normally open".

SECONDLY, you start the engine and the ohmmeter should show continuity as the engine oil pressure closes the switch to provide a path to ground. It is this "path" that provides a ground for the green lamp to illuminate.

If the switch doesn't immediately close and provide continuity, immediately stop the engine. At this point you will need to perform an oil pressure test with a mechanical gauge. If the engine has proper oil pressure then your switch has failed. If no oil pressure you will need to find out why.

No oil pressure issues can be caused by a faulty or incorrect oil filter.. if you are using an aftermarket filter, try a genuine Honda filter before assuming the worst.

Good luck.
 
I am the grandson of JackB1 and in possession of the boat now. I have read the comments on this thread and I haven't seen the oil pressure indicator light green. The boat has been running great until yesterday when a red light came on the oil pressure indicator and an alarm sound putting the boat into limp mode. This happened last year and we thought we needed to add oil which we did and the light and alarm went away until yesterday.
 
Yeah racerone, I don't know that outboard so I apologize if I misspoke. I know that the old twins didn't have external filters and I have always thought that was a mistake on Honda's part.
Although, there are still plenty of them still out there working just fine every day! So, who am I to criticize Honda?
 
So sorry.-----I may be mistaken here is this a 2 cylinder 7.5 HP or a 4 cylinder 75 HP motor.---Even boats.net shows a 97 model 75 hp to be a 2 cylinder motor.----100HP also shows a 2 cylinder motor.-----You would think they would have updated their info by now !!-----Sounds like it might be first year production of big HONDA outboard.-Pictures and model # of this motor ?
 
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I have 2 90's (same engine as the 75 hp) of my own, and have seen and worked on quite a few others. My experience is that ALL have a filter mounted on the front of the engine. Near impossible to tell for sure what year these were built, so there is a chance some were built without a filter but I haven't run across one yet.
 
racerone,

For some time now, boats.net has listed the B75 (7.5hp little twin) under the 75hp heading. They have also listed the B100 (10hp little twin) under the 100hp header.

I don't know why they haven't corrected this MAJOR BLUNDER on their website because I have personally contacted them to point it out and asked
that they correct this.

I believe that many others that use the site have also asked them to straighten out this very confusing set of listings. It has been like this ever since they last "updated" the site a few years ago.

I have learned to just work around it when ordering parts or doing research to help someone.

Aggravating to say the least.
 
Just to be clear. The Honda BF-75 is a 4 cylinder with an external oil filter. It is basically the same engine as a BF-90 which has some carb refinements to get the extra HP. The engine is really a Honda Civic engine turned on its side. In the early versions of these engines some used Mercury lower units so one has to be careful when ordering parts and have the SN handy. Just a quick question for anyone with this engine. The dipstick has about 4 inches of Xs to indicate oil level. If the oil level is 4 Xs below the top about how much oil would it take. Full is 4.8 quarts. How far down would it need to get before throwing a signal or is there no signal at all for low oil?
 
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Okay, this is getting confusing now. Honda have never had a red oil alert, not even back in '97, it has always been a green light illuminated to indicate good oil pressure. Those engines if you have the correct original warning light panel, had two lights. oil- green and on with engine running and red only coming on when there is an overheat detected. You said you had a red light, that is an engine overheat, not an oil pressure failure alert. Given this engine is 23 years old and used in saltwater it would suggest you more than likely have an overheat issue.I would be looking at a full cooling system service
 
To answer your question about oil level, I have seen these engines with as little as 1 litre in the sump not showing on the dipstick at all and no oil alert. The pick up it at the lowest part of the oil pan so needs to be virtually empty to show an oil pressure failure.
 
Just to provide an update it was decided to take boat to marine mechanic for evaluation of the problem so will keep you updated. One comment from the mechanic that I question is one regarding the oil filter. For over 10 years I have used the Honda Civic oil filter from Napa mainly because it saves a lot of money and the engine is a Civic engine turned on its side. No problems all that time. The mechanic made a comment that he sees this as an issue that could have caused the problem. Said it should use the Honda marine engine oil filter. Any comment on that?
 
I will say that, in the last decade or so, we have seen some real issues in the automotive industry with using many aftermarket oil filters. For example, Fram filters were, at one time, a most trusted brand. But, the quality in that brand has been questioned by many mechanics and shops after researching lubrication failures in engines that were ultimately blamed on filter failure.

I have a good opinion of NAPA brand filters and don't know of any lack of quality testimonials regarding them. But I don't use them regularly and, like many techs I know of that work on Ford vehicles that recommend ONLY OEM filters for that line's latest engines, maybe your mechanic has seen something we haven't.

I use and trust WIX brand oil filters on all the engines I have based on evaluations I have read regarding materials and performance including bypass and anti drain back valves.
 
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Can't see a problem using a good known brand of oil filter if it's compatible, tho I personally feel the extra dollars every 100 hours or so for genuine with genuine parts warranty is money well spent. I do not use anything other than Honda branded parts on my or my customer's motors.Gives me peace of mind and takes away these sort of questions. I still think this problem has nothing to do with oil pressure just rereading your description of the problem although it's hard to diagnose accurately based on this information given in this particular case.
 
Ian,

I think that your "policy" of only using Honda filters is a good one. It gives you and your customers peace of mind. And, at the $3 or so additional cost for that "security on the water"...
....I would say that you are providing your clients with a true bargain!

Just sayin'...
 
After a marine mechanic looked at the engine he said the problem was a corroded thermostat. Go figure!! Getting some other work done as long as it is in the shop. Will let you know after dunking the boat if that cleared up the problem. I am curious, do the warning lights on the shift control indicate an over heating event?
 
Yes it apparently was an overheat alarm. Grandson learning a lot about engine issues. Thermostat was replaced along with water pump and spark plugs as long as it was in the shop. Boat running great on last report. Appreciate the help.
 
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