1996 BF50 Honda Bogging out when trying to plane

[Noah4200]

So i did my carbs a few months ago and the boat ran great for 3 outings. It was giving a sputter at trolling speed every minute or so and I turned the fuel screw to 2 turns out and it went away (suspect it was a lean sputter?). Today after trolling around the creeks for a few hours it started the sputter again so i tried to get on plane and it was cutting out badly could not do it. I let the motor cool and switched fuel tanks and didn’t help. Got progressively worse to the point i barely made it back to the dock: The fuel is only 2 weeks old ethanol free with treatment in it. I did notice the middle carb seems to have a slight amount of fuel leaking from the float bowl seam/drain area (weird bc all new gaskets) but it didn’t seem to be coming from the vent (stuck float). Upon bringing it home i lowered the motor to flush and it started and ran great with a higher idle. Revenge slightly did not bog out but of course there was no load. Could be bad fuel (but unlikely) or moisture in filter but l looks like i’m going to have to pull apart the carbs which is crazy after less than 10 hours. Any ideas and would i have to get all new gaskets again? The look nice and new/green still. Btw i let the motor cool down on the water just too rule out an issue with heat (air leak/ignition coil) and it did not help.

 

[MattFL]

My first guess would be a fuel issue of some sort. Either dirt in the carbs, or maybe a stuck float, maybe an air leak in the fuel line somewhere. Is the under hood fuel filter clean? Did squeezing the ball resolve it temporarily?

 

[Noah4200]

matt i cleaned the carbs spotless all new gaskets and orings. felt really smooth out but still bogging today and won’t plane. feathered it and got sooo close. i really don’t think it can be carbs at this point i flushed the small passages like crazy and used compressed air. My only thoughts are that extended idling around sightseeing fouled the plugs…like last 3 trips all we did was idle around and i had the fuel screws at 2 1/2 turns out to combat a sputter. i foolishly didn’t check the plugs. you think on a 4 stroke it could be just a gunked plug or 2? we are anchored up fishing just trying to save the trip.

 

[Noah4200]

i bet that is it! Put some new plugs in and turned the fuel screws back to 1. Going back out tomorrow wish me luck!

 

[MattFL]

Those don't look terrible, and they're not wet. Looks like lots of idle or slow speed time. I doubt it's the plugs, I guess you'll find out tomorrow. Did you check for fuel in all of the carburetors, and try squeezing the ball to see if that helps? Also are you sure the choke plates are fully open? Does momentarily tapping the choke, or applying 1/2 choke have any effect?

 

[Noah4200]

Those don't look terrible, and they're not wet. Looks like lots of idle or slow speed time. I doubt it's the plugs, I guess you'll find out tomorrow. Did you check for fuel in all of the carburetors, and try squeezing the ball to see if that helps? Also are you sure the choke plates are fully open? Does momentarily tapping the choke, or applying 1/2 choke have any effect?

yeah i know they aren’t shockingly bad…adding any choke made it worse and pumping the ball has no effect. Low speed performance got worse and worse the warmer it got..sputtered back to the dock. But even a cold motor at the start of the day wouldn’t plane when low end still felt great. A few times the engine speed would increase on its own and sound much healthier like it was firing again for a few seconds. I’m wondering if it’s exciter, pulse or ignition coils. Or even CDI. I already replaced the delaminated flywheel that was tapping the coils and making noise. Wonder if they are damaged bc of that. We have 2 more days of fishing i screenshotted all the electrical diagnostic specs and procedures to try to get a multimeter on it in the morning. I can’t see it still being carbs i ran a ton of cleaner through all the passages both ways and covered ones with my fingers to build pressure and also compressed air. The small parts were put it ultrasonic cleaner and those needle jets are new .

 

[Noah4200]

The more i think about it…it was doing this somewhat with the flywheel banging when i first got it. My theory was that the magnets hitting the coils hundreds of times a minute would heat them up due to friction and performance would break down. When i replaced the flywheel everything was great but now it’s back. Is it possible the damage was done and the coil/s are now failing even though the flywheel is no longer hitting them?

 

[Noah4200]

Yeah guys i thought about it all night and the longer we idled the worse it got all around. At the end it was harder to even start and we barely made it back. There were 10 second periods where rpm would go up and boat would sound good. Once we were back in the driveway it started instantly and sounded great. It’s either electrical/ignition or has a ton of carbon buildup that’s causing excessive combustion chamber temps or something. I guess it could be the little diaphram fuel pump but idk. Not sure how i would even test the fuel output. My plan today is to test everything i can with the MM and check all grounds and connections

 

[Noah4200]

Ok tested everything except the CDI.. Everything checked out on all connections seem clean. I know things can test ok cold then fail hot. I’m about to try to decarb in the driveway. I don’t want to separate my new fuel set from the tank compression fittings so might just mix up a gallon of fuel and a can of sea foam in the second 6 gallon honda tank.

 

[Noah4200]

k!!! Huge break…did a plug drop again in the driveway and #2 made no difference. tested spark NO spark. Swapped coils…still no spark. This means CDI correct?!?!

 

[MattFL]

See if you can get a tester on the coil input for one of the cylinders that is working, and check what that looks like. Then repeat on the cylinder that isn't firing, see if it looks the same. If you have an oscilloscope, maybe you can wrap some wire around one of the spark plug leads a few times then connect that to an oscilloscope and perhaps get a clear signal, I'm not sure, haven't tried it myself but this is what I would try if you have a scope available. If you have to buy something, there must be a tool for this.

 

[Noah4200]

See if you can get a tester on the coil input for one of the cylinders that is working, and check what that looks like. Then repeat on the cylinder that isn't firing, see if it looks the same. If you have an oscilloscope, maybe you can wrap some wire around one of the spark plug leads a few times then connect that to an oscilloscope and perhaps get a clear signal, I'm not sure, haven't tried it myself but this is what I would try if you have a scope available. If you have to buy something, there must be a tool for this.

Are you saying like a DVA on the 3 pulser coil outputs?

 

[Noah4200]

Ok i guess the pulser coil does have 3 individual outputs so i guess it would be a lot more apt to be breaking down under heat and load then the robust CDI. It’s also cheaper and more available. So without guessing i need to be able to test pulse coil output. I’m guessing i need a DVA

 

[Noah4200]

Ok got the new pulser coils on and tried it out yesterday. The motor seemed really smooth and i went ahead and planed within a minute of launch and it got up nicely. I quickly noticed it would bog out above 3/4 throttle but when i pulled back to half it smoothed out. I dropped speed and tried to plane again- well it got worse and worse till it wouldn’t plane anymore. By the time i got back to the dock it was misfiring every 10 seconds or so even at a slow idle in gear. So IMO the pulser did nothing. It’s something heat related. Either ignition coil/s or exciter coil. The carbs have been cleaned twice this year i really don’t think they would be ok for awhile and then cause misfire. My problem when i got this boat was the flywheel magnets delaminating and banging the coils underneath. I replaced with a new factory flywheel but i noticed marks on the charging coils and i’m sure it wasn’t good for the exciter coil. I’ve tested resistance of the coils and everything checks out ohm wise in the driveway. I understand this does not tell the whole story tho. Compression is 180 on all 3 at 3-400 rpm off starter so great imo. Oil looks clean and clear no water or anything. I’m thinking of ordering a used tested 90 day warranty exciter coil off ebay for 25$ first? Just trying to decide how to proceed. Attached sounds similar to my symptoms and was due to an exciter coil collision failure

 

[Noah4200]

Ok i have a exciter coil and set of coils/plug wires coming all mint and tested with warranty for 80$. So i’m 100$ in and will have all major ignition components replaced except CDI. This should be a big leap forward. If this doesn’t work i will have to look at connections/grounds and the CDI more intensively. I can’t see carbs starting off running great then fall out 10 minutes later repeatedly. Two concerns- How reliable are these diaphragm fuel pumps? Should i throw a new one on just for peace of mind the old one looks peeling and old? I have pumped the bulb exceedingly during rough running with no change so does this 100% rule out fuel problems? Also- The top cylinder being 180-185 around water jacket/plug area vs the 2 lower being like 160-165. Is this a problem? Or does the heat just rise and this is normal I have a new anode and water jacket gasket but i see horror stories and can see buildup on the edge of the water jacket cover. I know it’s gonna be a mess and the bolts will be VERY hard to get out. Should i go ahead and open it up and clean it out? My boat pees great and never overheats but i’m concerned the top passage is heavily clogged. I do have a bolt-buster induction bolt heater that may be able to get the jacket cover bolts off smoothly. I guess my last theory is that the top cylinder is overheating 185+ causing these misfires but not triggering the alarm bc the overall water temp of the system is still 165….

 

[Noah4200]

those temps were in F btw

 

[MattFL]

I would not try to remove the exhaust anode cover. Instead, get some Rydlyme and flush the system, I posted a thread here about it somewhere on the 1999 version of the same motor, complete with instructions and photos. That will clean out more scale than you could manually scrape out anyway. To completely rule out fuel; when it starts running bad, immediately drain the fuel from each of the carburetors and note how much comes out. The general idea is make sure all 3 bowls are full of fuel. I don't think that the top cylinder getting hot would cause the problem, instead I think it would run just fine until it had a heat related hard failure (head gasket, seize, etc..).

Here's a link to my post: https://forums.iboats.com/threads/descaling-flush-motor-that-stops-peeing.747060/

 

[Noah4200]

Man i wish i would have read this earlier broke them all but the bottom 2. That’s with kroil and bolt buster heat. Not happy .

 

[MattFL]

Hey, at least the 2 that didn't break are the 2 to not break! It's an easy fix if you're patient. I've been there, see this thread:

Best method to drill out a broken off bolt

Can anyone give me your favorite method for drilling out a broken off bolt? The part that makes me nervous is doing it free-hand, not under a drill press. Are there any tips or special tools for trying to keep the drill bit centered? Maybe a collar of some sort I can slip around the bit that...

forums.iboats.com

 

[Noah4200]

Hey, at least the 2 that didn't break are the 2 to not break! It's an easy fix if you're patient. I've been there, see this thread:

Best method to drill out a broken off bolt

Can anyone give me your favorite method for drilling out a broken off bolt? The part that makes me nervous is doing it free-hand, not under a drill press. Are there any tips or special tools for trying to keep the drill bit centered? Maybe a collar of some sort I can slip around the bit that...

forums.iboats.com

i know! i was extra careful with those bc of the clearance with the casing! Today i’ve been spraying and heating. I was able to get the anode out so that’s good. Gonna borrow my father in laws mig welder and weld nuts on them. I’ve had great luck in the past with this. I’m going to u plug CDI and battery and then clamp the ground directly to the nut (basically hold the nut with the ground?) so nothing passes thru the block. Since it’s aluminum i think even the recessed one can be bloobed up for a nut too. The weld shouldn’t stick very easy to the Aluminum and i might use a copper tube. Sound ok? i’ll check your link out too! thanks