ftpiercecracker1 Posted July 26, 2019 Share Posted July 26, 2019 Really hoping someone here can offer some advice because I'm about to toss this GD thing into the drink. Its an old Honda 4 stroke BF7.5hp. Was a great little motor for a while, then my dad used it one day, literally one afternoon, and it hasnt been usable since. Its running very rich, some smoke but turned new spark plugs black after just a minute or two of running. It will start fairly readily, but will not rev up or stay idling. Meaning the rpms drop over about 10 seconds until it stalls out. Even with the idle screw at max idle speed. If you give it gas it will stay running indefinitely, but as i said it stutters hard when you try to rev it. I have cleaned the carb with surgical thoroughness three different times and no change. I also tested the float to make sure it didnt have a pin hole, letting it fill with fuel, allowing it to sink and let to much fuel by. Still very rich, will not rev/stutters. I have tested the spark (old Autolite) and discovered that one of the plugs was not jumping the gap but actually arcing inside the spark plug. Eureka! I thought. Neither one seemed all that consistent so i figured i would replace both with a nice set of NGK pre gapped to .28 per factory spec. Tested spark again with new plugs. Very good, strong, consistent spark on both cylinders. Put it back together and no change. Still running like dog sh*t, stalls, won't rev, black plugs in minutes. I started the motor and disconnected one of the plug wires, wooden handle no shocky me, and noticed an extreme amount of arcing from the wire to the motor body. Which makes me think bad wires, but the wires and coil are made together. I tested the coil and neither lead has continuity from plug end to stud on coil. Which makes no sense seeing how i have excellent spark. I am at a loss, i don't know what to do. Also, I can't do a compression test because my assortment of adapters don't fit the plug hole. It just gets better and better. I will add some pictures for your viewing pleasure. Link to comment Share on other sites More sharing options...
Pete M Posted July 27, 2019 Share Posted July 27, 2019 what the heck? all those problems fixed and still no change? just use it as an anchor and install one of these: Link to comment Share on other sites More sharing options...
FrankTheDog Posted July 27, 2019 Share Posted July 27, 2019 Did you dump the gas out and try it with fresh gas? Link to comment Share on other sites More sharing options...
Old man with MJ Posted July 27, 2019 Share Posted July 27, 2019 I have a Honda motor on a lawn motor, the carb has several nylon or plastic parts, the float also, if those are purchased separately it cost more than a new carb, repair shop replaced the carb. Don't know if gas caused this, but I started adding the chemical stuff to my gas can when I fill it up. Link to comment Share on other sites More sharing options...
ftpiercecracker1 Posted July 28, 2019 Author Share Posted July 28, 2019 On 7/26/2019 at 8:52 PM, Pete M said: what the heck? all those problems fixed and still no change? Yes and its utterly infuriating. 19 hours ago, FrankTheDog said: Did you dump the gas out and try it with fresh gas? Bought 90 oct, Non ethanol the same day i started working on it. Hose ran directly into gas can. I have flushed gas lines all the way to the carb with good clean gas. Along with the carb, spark plug, plug wire issues i also discovered the fuel pump has a tiny filter in it that was darn near completely clogged with dead insects. Again i thought "Eureka! The problem has been identified." Only for my feelings of jubilation to be squashed when nothing changed after thoroughly dismantling and cleaning it. 9 hours ago, Old man with MJ said: I have a Honda motor on a lawn motor, the carb has several nylon or plastic parts, the float also, if those are purchased separately it cost more than a new carb, repair shop replaced the carb. Don't know if gas caused this, but I started adding the chemical stuff to my gas can when I fill it up. Only plastic bit in this carb is the float and the needle. Everything else os either aluminum or brass. I tested the float in a jar of gas to see if it would sink and despite turning it every which way while submerged i saw no bubbles. As far as I understand, there HAS to be something wrong with the carb. No two ways about it, if it's running rich it's a carb issue. Is this sound logic or is there another way for the engine to run rich without the carb being the problem? Link to comment Share on other sites More sharing options...
Manche757 Posted September 5, 2019 Share Posted September 5, 2019 Did you get it running? Link to comment Share on other sites More sharing options...
Eagle Posted September 5, 2019 Share Posted September 5, 2019 The other way for it to run rich is if the air intake is severely restricted. Link to comment Share on other sites More sharing options...
ftpiercecracker1 Posted September 6, 2019 Author Share Posted September 6, 2019 Nope, shelved it for now. I can't do a compression test because my compression tester doesnt have the right adapter. And i don't know how to test the electrical bits. It has two "coils" under the flywheel, an ign module and a firing coil that has the actual plug wires. Which are non serviceable too. Two of these under the flywheel One of these. Why is this needed? And one of these where the spark is actually generated. Link to comment Share on other sites More sharing options...
ftpiercecracker1 Posted September 6, 2019 Author Share Posted September 6, 2019 Why do i need an ignition module/power pack? My lawn mower doesnt have one Both of these engines are small and carburated. Actually the outboard is is half the size of my lawn mower. Maybe its just a packaging issue? Not enough room for the coil to be under the flywheel so the "powerpack" is simply a remotely located coil? Link to comment Share on other sites More sharing options...
cruiser54 Posted September 6, 2019 Share Posted September 6, 2019 You Tube the coil tests. Are there any diaphragms in the carb that mighta gotten messed up by old fuel? Huge vacuum leak anywhere? Is the needle and seat actually SEALING? Link to comment Share on other sites More sharing options...
JustEmptyEveryPocket Posted September 6, 2019 Share Posted September 6, 2019 22 minutes ago, cruiser54 said: Is the needle and seat actually SEALING? This is my thought as well. Have you tried putting some lapping compound on a q-tip, putting the q-tip in a drill and polishing the seat? Then polish the needle to match. You might also try tweaking the arm of the float so that is pushes the needle sooner. Link to comment Share on other sites More sharing options...
yxmj Posted September 7, 2019 Share Posted September 7, 2019 Just curious.....if you do an old fashion spark test....(pull the plug and ground it on the head) you say you have excellent spark......what color is the spark? Link to comment Share on other sites More sharing options...
ftpiercecracker1 Posted September 7, 2019 Author Share Posted September 7, 2019 Gentlemen i appreciate your interest, but i will have to get back to you on this one. Sorry Link to comment Share on other sites More sharing options...
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