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bf75 no spark need coil no fuel carb has been cleaned

D

Dognutz

New member
Hello All,
I got a used late model 1970's bf 75 was told it ran but it doesn't. It seems to have good compression. I took the carb off and cleaned it really well. I get fuel in the bowl but when I pull the cord gas doesn't seem to be available. The plugs don't get wet and there is no fuel going into the intake? I took off the fuel pump it seems to operate (the cam button moves freely) but don't know how to check it. I cleaned the fuel filter too. I pulled the tube from the pump to the carb and pumped the bulb and fuel flowed easily. I'm not sure what else to do any ideas would be great.

The motor also has no spark. From what I can see the timing was off. I set the punch mark aligned with the T mark on the flywheel. Still no spark so I checked the primary coil and checked out fine with book. Next I checked the secondary coil (with spark plug wires) and the meter would spike to about 17 for just a second and then go to 0. I also checked the rectifier by the book and it is also bad. The coil and rectifier have been discontinued. Does anyone know of options for these parts other then the used route? I have been looking for used parts without success so far. Are these motors trash since the parts are discontinued?

Thanks in advance!
 
Hi,
What type of meter are you using? A DIGITAL VOLT OHM METER (DVOM) works best. When you do the ignition coil secondary check, you have to remember to put your meter on the correct scale if it is not an autoranging DVOM.

The secondary circuit of the ignition coil should read 31.5 k ohms. Translated it means 31.5 THOUSAND ohm. So, the meter should be on a scale above 40,000 or 40k ohms to get a reliable reading. Also, you obtain that reading by placing your probe ends...black into one spark plug end and red into the other spark plug end. Are you doing all of that?

In addition to that check on the ignition coil, there is another for the "primary winding". That should be 1.5 ohm for the breaker point ignition coil. Although, it is my experience that anything less than 2 ohm will fire the plugs.

These old babies are GREAT engines! Don't throw it away quite yet. And, if you do, throw it my way!

Let's talk about it. I don't know everything but I have lots of "theories"! :)

Also, if you are checking the resistance of the "primary" coil, then that tells me that you have a breaker point ignition system. Is that correct? If so, then the timing mark for ignition is an "F" on your flywheel. The "T" is for valve timing.
 
Yes I am using a digital meter. I'm pretty sure I had the scale set correctly. Yes I tested like you said, I got 2.2 ohms on the primary. Yes I have a points ignition. I will reset the flywheel to F, I may have read my shop book wrong. Any ideas about the fuel?

I will call a local dealer today. I called an aftermarket place and all they would say is "part is N/A" and offer no suggestions.
Thanks again!
 
Well, like I said, I'm "chock full" of theories.

First off, yes, re-read the point set procedure and you will see that the points need to be OPENING just as the "F" mark on the flywheel comes to the punch mark on the starter case.

Also, the spark from these engines is actually VERY faint looking and many people have ADEQUATE spark to fire the engine but think that they don't when trying to look for it in a brightly lit setting. One sure way to make sure is to check at night or in a darkened garage. Or throw a blanket over you and the engine to make a sort of "dark room". Awkward but it works.

As to your fuel delivery, it sounds like your pump is working ok. But, the pressure should be 2.5 psi. if you want to check it. That is almost nothing. If you remove the delivery line from the carb and pull the starter rope, if there is a "gurburbble" of gas coming from the pump then it is, most likely, doing it's job.

The carbs can fool you. They are harder to get "reliably" clean than most people think and if I had a nickle for every guy that has told me "I cleaned the carb real good" only to find out the carb was still in need of service/cleaning well...I'd have a BUNCH of nickles! So, many questions about that. But first, some basics...

Are you opening the vent valve on your fuel tank all the way and is it clear? No pinholes in an old fuel line that could "suck air"? Ok? Now back to the carb.

Did you take the idle mixture screw out and flush the circuit forward and back and make SURE that carb spray would come out the idle passage orifice at the top of the carb throat just behind the throttle plate?

Did you take out the "emulsion" tube and main jet and spray up into the orifice the emulsion tube feeds and VERIFY fluid comes out of orifices at the top of the carb throat IN FRONT of the throttle plate?

Slow jet? Did you take it out, clean the passage and replace the little "o"ring?

There are two ATMOSPHERIC VENTS at the top of the carb and little critters like to get in there and set up house when an outboard is left sitting for long periods. These vents are CRITICAL to fuel movement within the carburetor. Make sure they are completely clear.

As to the availability of parts for these, yes it is true that the ignition parts for the breaker point style system are no longer available. But, the CDI parts are still serviced and I THINK a CDI coil would work with your outboard. I'm sorry, I have never ACTUALLY tried it so it would be a $110.00 gamble for someone that wanted to.

Below is a couple of parts links from boats.net with your ignition system depicted. You can readily see thaqt the parts are OBSOLETE. But I will also include a link to a CDI model and you can see that the coils LOOK identical. I've ohmed some out and they do have slightly different primary coil resistances (1.5 ohm for breaker point coil as opposed to 0.8 ohm for the CDI) but they are pretty close and the secondary is exactly the same at 31.5 k ohm.

Breaker point coil page:
http://www.boats.net/parts/search/H...B75K1 LD /IGNITION COIL + FLYWHEEL/parts.html

Breaker point ignition points page:
http://www.boats.net/parts/search/Honda/Outboard Engine/0/B75K1 LD /CAM PULLEY + POINTS/parts.html

CDI coil page with pricing:
http://www.boats.net/parts/search/H...A /C.D.I. IGNITION COIL + FLYWHEEL/parts.html

Fixing one of these old engines can be a frustrating experience at first but they are great old outboards and run like tops when you get them all sorted out.
 
Wow! I read some of your other posts thank you for chiming in! You have given me hope and many things to test. I will test my electronics again before trying to get new parts. I saw the CDI and points type were similar but wanted someone to confirm, maybe I will be the guinea pig. I'm not familiar with carb'ed small engines so I may have to check my terminology. I soaked the carb in cleaning solution over night and removed the main jet (the one under the float). I only took out the main jet the piece under that (I think it the emulsion tube), and the plug screw. I then took a wire and poked in ever hole and then blew it out with air but, I didn't take out the idle mix circuit screw. I don't know where the slow jet is or how to take out the slow jet. Can you tell/show me where and how to remove it? Are the Atmospheric vents little ball bearing looking things set in the body of the carb? I saw those and they seemed to be painted/stuck shut and didn't want to force them to move. I didn't check the fuel tank vent, I'm new to boat motors and didn't realize there was a vent. It sounds like you are right about needing to clean the carb more. I will try and verify that spray comes out in front of the throttle plate. I will report back after some more investigation. Thanks again for all your help!!!
 
Glad to be of some assistance. Most people struggling to fix their outboards need MORAL support more than anything else. Staying positive and not giving up is key to "gettinerdone". Most of the "helpers" on this forum are pretty good at that and do so happily. That's why I hang around. I learn something at least once a week from somebody here on this forum so it is only fair that I try to give back.

Anyway, back to your baby.

Before I get ahead of myself, it would be best if we know what carb model we are dealing with. I am sort of assuming you have a BC but, if I'm wrong, we could make some major mistakes getting you squared away. Please look near where the carb bolts to the intake runner and see if there are some letters stamped on a portion of the mounting bolt passage. Look at all the "corners" of the carb if you don't see it right away. You are looking for two letters. I predict you'll find BC but let's see for sure.

The little "ball bearing thingys" are the caps for the passageway drillings and are NOT to be disturbed!! But, if you are looking at them then you are looking at the vents and that is good. Just go to the other end of the little "tunnels" that those balls seal off and that is the opening of the vents.

When you can get back to me on the carb model letters then we'll explore a little more deeply.

And, don't forget...it's a boat! So have fun! And...spend lots of money! Well, a little anyway.
 
The carb number is you guessed it "BC inside circle followed by 01cBsh7 B inside box" I took apart the carb again and removed the idle air mixture screw this time and cleaned. I didn't see anything else that could be removed (minus the parts removed above). I blew air in all orifices and everything flowed fine. I had a leaking line going to the carb and when I tried putting a clamp on it I broke off the barb which is now being JB welded back on. I checked the points and they were almost always closed so I set the gap to .013 max opening, the range per the book .012 - .016. The procedure for the timing belt says to "align the mark in the T and the punch mark" maybe I'm reading the wrong procedure. I will update when I get the carb repaired and back on. I'm stressed at all the nice days no sailing lost to no motor. I hope I can with your help get back on the water.
 
Hi Dognutz,
I'm looking at page 22 of the Helm Inc. Honda shop manual for ignition timing. Are you saying that your flywheel doesn't have an F stamped on it? It should be just to the left of the stamped T. as you are looking down on the flywheel. Yes, the point "gap" should be around .015" but the points should BEGIN to open at approximately 15 degrees of rotation before top dead center (BTDC). One other component that is often overlooked with spark problems in a system with breaker points is the condenser. It is actually a capacitor and if it is shorted to ground, the coil won't spark. These use a 0.24 MFD cap and they are no longer serviced. But, a substitute can be found through electronics stores.

My computer is acting up so I'll get back to you later about the carburetor.

PS. Love sailing and sailboats. I own a few. Health issues keep me off the water these days so I know how you're feeling.
 
Thanks for your support! After setting the timing to the "F" mark, setting the points, new carb and fuel line and cleaning the fuel system she fired right up and purred. I checked my values again for the ignition bits and values were strange so I just put the ignition pieces back on and tried it and she worked. Another note I couldn't get the nipple to stay attached where I broke it off so I ordered a new carb. It looked like a newer design but works perfect.
Thanks again.
 
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