1996 BF50 Honda Bogging out when trying to plane

[MattFL]

A few things; the Barnacle Buster is going to be exponentially stronger than vinegar, no need to bother with the vinegar. After you're done with the chemical flush, flush the heck out of it with clean water to get all the chemicals out, you don't want to leave that sitting in there.

To flush; just remove the lower unit, remove the thermostat and pump water into the water feed tube that normally goes to the water pump. That will get water everywhere it needs to go. If you got water in the motor, the most important thing is to get it out before anything rusts. Change the oil (any water will be sitting at the bottom of the pan) then run it on the hose or the boat long enough to get the oil hot for a while so any remaining moisture steams off, then you should be good.

 

[Noah4200]

Allright back together…engine runs great. Pee is strong AF. There was like a half inch of sediment at the bottom of the bucket. Pic is what was left after dumping…there was way more looked like a lake bottom. Thermostat housing looks great…confirmed that it opens. Just let run for 20 minutes on the ears and cylinder temps were 165 top 150 middle and like 140-145 lower. Way better than before i swear the top cylinder was getting to like 175-180. Gonna take it out for a test ASAP. Months of setbacks coming to and end it feels…

 

[Noah4200]

Look at this from november…I’m at 165 now guys…140 on the lower cylinders. 20 degree drop. It’s going to work. I know it. Overtemp is 190. I was hitting 185 idling…everything is making sense. The second i gave it rpm it was overheating. There may have been something intermittent with the middle cylinder plug cap too but we will never know. Thanks for all the help everyone!-this motor starts instantly now and is soooo smooth with the repeated carb cleans and syncs. I’m almost 100% the sea trial will be successful. Will let you all know

 

[MattFL]

Excellent! Please report back and let us know how it goes. It's amazing how much crap comes out with a proper descaling rise isn't it! My motor was the same. I flush the heck out of it, usually 15 min on the muffs while I scrub the rest of the boat, but apparently not all of it comes out with a fresh water rinse and after 20+ years of salt use there was a lot of stuff built up.

 

[Noah4200]

thanks Matt…hopefully go out this afternoon. I plugged back in the trim box in the back and the trim alarm was buzzing so i don’t understand why the overtemp didn’t buzz. The red light clearly worked. My only guess is that the trim connections disrupted the circuit? So i unplugged just the black single ground on the trim indicator box to stop the trim buzzer and reconnected the plug (which looks to have 2 or 3 connections). Would i just short the temp sensor to test the temp warning buzzer ?

 

[Noah4200]

Ok guys!!! NO OVERHEAT! Was able to plane and run around the bay for 20 minutes. Was low tide and late but i’m very relieved. The boat ran a little rough at certain throttle levels (mainly 1/3 and WOT) so i had to kind of hunt around but the gas is 6 months old and has been sitting out getting rained on and contracting and expanding with this georgia weather. I also DID NOT drain the float bowls again since my last carb clean 6+ months ago..although i did add a little treatment. Also my reverse flush mishap might have pushed some particle into the carbs . I’ve seen the fort lauderdale youtube guy who has a carb 2 part video mention he is cleaning them again after like 6 weeks and i know they are notoriously sensitive to contamination. So the plan is fresh gas and run it hard on a better day for a few hours and if it doesn’t clear up do the carbs again. I’m actually getting good at them and it’s no big deal anymore. Sound right? Thanks again! I have a working boat!

 

[Noah4200]

Allright i did a meticulous carb clean…i mean whole carb in ultrasonic with carb formula multiple times, air compressor, carb cleaner thru all fine circuits multiple times. Covered individual fine holes and flushed thru pilot circuit both ways and confirmed output. All needle jets were replaced last cleaning but i even made sure they were clear again. Checked float height…new oring with a bit of silicone grease. STILL bogging out and getting worse and worse with time to the point where even off idle to 1700 rpm is rough. BUT NO OVERHEATING (must have been a separate issue). Barely got back. Fresh ethanol free fuel. ALL new OEM hoses and prime line. I mean i checked dashpot and everything. Already swapped all 3 coils, pulser coil, exiter coil!!! Compression 190-195 PSI. All that is left is fuel pump and CDI. Fuel pump is original diaphragm pump from 1996. I mean 28 year old pump with rubber diaphragm. pumping the bulb actually seemed to make it worse. Should i go ahead and just do the fuel pump? Each time it seems to get worse and worse. Last time it was cold out and i planed right off the dock so i didn’t run it long enough for deterioration to happen. Here is a clue from this time- it’s intermittently trying to run strong. Every 5-10 second power will return. As if struggling for fuel or spark (deteriorated pump or CDI component deteriorated). Listen to this video-

 

[MattFL]

While it's acting bad, squeeze the ball. If that resolves it, then you've got a fuel delivery issue, such as the pump or clogged filter somewhere. If that does not improve it, immediately turn off the motor and drain each of the 3 carburetors to see if they are full of fuel or mostly empty. Or perhaps easier, try an external fuel tank and entirely different fuel line. What can happen sometimes is the inside liner of the fuel hose can separate from the rest of the hose, and that liner can collapse blocking fuel flow. Imagine stuffing a balloon inside the fuel line, it just clogs stuff up. I'm referring to the fuel line between the tank and the motor.

 

[Noah4200]

Well Matt…it’s a brand new OEM Honda line and bulb and a brand new tank pickup. Pumping the bulb does nothing and actually maybe even makes it worse (possibly). Can the fuel pump still be bad when pumping the primer has no affect? My theory is the inside of the fuel pump is heavily deteriorated and possibly partially clogging the output. I have not tried to empty the fuel bowls at the moment of problem but aren’t sure i’d be able to tell if too little was in there or not. I feel like nearly 30 years is a long time for a fuel pump…it looks heavily worn on the outside. For 90$ it would be nice to know it’s ready for decades more work regardless when this is all over The intermittent surging of correct running is something i didn’t notice before…just playing it in my head trying to decide if that’s an oscillating electrical or fuel. As bad as i want to say fuel i could see a weakened component on the CDI firing every so often too…similar to like a loose spark plug cap. I feel SO close to having this thing over with!

 

[Noah4200]

Also i did just pull the fuel pump off and pump the prime to see if it leaked…NO leak
There is a nice looking CDI on ebay for 290$ from a reputable seller. Fuel pump is 90$. i can see the finish line…tough call. I’ve gone thru this whole motor…timing and valve adjustment too…carbs spotless and synced. Looked at all plugs and grounds. If it was kill switch or something i dont see it progressively getting worse with run time. I have security torx and could probably take the fuel pump apart for inspection

 

[MattFL]

In the morning when it's running properly, drain the carbs and measure what comes out of each one. Then when it acts up, immediately turn it off and measure what's in the carbs. That will tell you right away if they're full or not. The gas line is new, but is it "new" or new-old-stock? Does it have a manufacturing date on it?

To test the theory that it's electrical and the heat is causing a problem; get a can of freezy spray or big can of compressed air. When it acts up, remove the engine cover and cool off everything electrical you can find. Does that resolve it?You might also try running it without the engine cover as that will allow the electronics to remain much cooler, and see if that improves the situation any. Or you can do the reverse, warm up the electronics with a hair dryer (heat gun might be too hot to be safe), and see if that immediately invokes the problem.

You can of course throw parts at it if your time is worth more than the cost of the parts.

 

[Noah4200]

Ok Matt..thank you for being there for me through this. Do you think a 27 year old fuel pump has reached its lifespan? I’m thinking of just ordering it regardless. Be good to have a fresh one out there

 

[MattFL]

It's hard to say. There's no harm in replacing it, the biggest risk is it might be an unnecessary expense, so if you're OK with that then go for it.

 

[Noah4200]

Ok i ordered a new OEM fuel pump 85$ shipped great price. BUT honestly this whole time my heart has said CDI. Have just avoided they are not available new really and 300$ used even. Mine cosmetically looks great (but i know that means nothing). Seems with a bad fuel pump after sitting and pumping the bulb until hard the bowls would have to be full and give me another brief period of running. The only exception is that failed diaphragm pump can send a TON of air into the carbs creating a frothy mess as soon as engine is started…but i would still think it would run ok for a minute. Yesterday i sat with the cowl off for an hour at anchor and it still immediately felt terrible upon starting. I would think that the CDI would be cooled down AT LEAST as much then as the 5 minute off plane cruise off the dock where i was still able to plane with full power breifly. So here are my options:
1: measure out float bowl volumes at cold start and then after problems and compare to rule out fuel.
2. Get some sort of tool to measure spark at each cylinder WHILE running poorly. Maybe some sort of inductance tool? Can you use a DVA while running? I need something capable of giving me an on the fly reading/indication. This would finally rule out electronics!!! Should have done this long ago.

IF both those check out ok…then i may be dealing with something very serious internally that is letting loose as engine expands. Not running right after an hour cool down concerns me…i would think fuel pump rubber and CDI would recover with that amount of time. Where as engine heat soak would not.

What is my best bet for on the fly spark test?

thanks

 

[Noah4200]

How about 3 off these and go for a cloudy day?

 

[Noah4200]

OMG!!!! I tested the thermo switch for the heck of it today and it was not working on the panel, so I confirmed that signal was getting up to the helm and ground and it was and it got me thinking about the CDI again so I decided to go ahead and pull it off and test it. IT FAILED EVERY SINGLE TEST miserably like we’re talking 5000 to 8000 ohms when it was supposed to be 10 to 500 some of the legs didn’t even have continuity. I’m surprised the boat ran at all. When warm i bet the measurements were off the charts! I guess because of the unavailability and cost I avoided testing it (also thought it would only show bad when hot) because I was also told from a lot of pros that they’re very durable and rarely fail, but this one is absolutely trashed. CASE CLOSED. Thank you so much MATT! A year of hell is over. My intuition this whole time has been CDI. I’m going to source one and get back on the water. I did see a place that looked to have a new one for like 550$. OUCH

 

[Noah4200]

I bet my the old flywheel magnet delamination contributed to the CDI failing. Sending junk pulses into the circuit with each strike. So if you have magnets hitting better address it ASAP

 

[MattFL]

I hope that's it, please be sure to post back and let us know the results!

 

[Noah4200]

Just for clarity…ALL my measurements on the CDI are showing 4-5 MEGA OHMS. The honda specs call for 5-500 kilo ohms. So we are out of spec by a factor of 10X!!! A few legs don’t even have continuity! These legs look to go to the front helm control and I believe this is why the warning buzzer doesn’t work as well as intermittent overtemp. I jumped 12v and buzzer is fine and shorted temp temp sensor and NO red light even tho signal and ground are good at the light plugs.

Hoping that it runs better than ever and warning system functions. With the 10x resistance at room temp on the Power control circuits i bet it’s gonna feel much better

 

[Noah4200]

CDI will be here friday. Paid 250$ but got the nicest one on ebay and from a 100% seller. I put the new fuel pump on today. After testing old one with less than 5 psi like on danger marine it developed slight leak near the corner security bolt so i’m glad i swapped it too -probably was close to failing. If i ever wanted to manually clean out my head passages to get 100% original cooling back do you think the head bolts would be as bad as the water jacket bolts? Or are they more stout and less prone to corrosion?