Logo
FULL SITE MENU

Please help... its not the carbs 2007BF30

D

DRK66

New member
2007ish Honda BF30 carbureted. I took the boat out of winter storage recently. She ran well when put away with float bowls empty.
Filled the tanks with fresh premium.
Primed the bulb and she started and sounded normal for about a minute. Then she started to labor. And got progressively worse.
She will now only run for a brief time on choke. Not at all under increased RPM.

I have considerable experience with carbureted 4 stokes of other types and i have serviced carbs successfully dozens of times.
To date i have: Thoroughly cleaned the carb several times. Main jets, idle jets (no they are not cracked. yes i know about the holes on the side. they are clean)
emulsion tubes, By starter circuit, intake and vacuum tubing. new line from tank, new filter, no leaks. The idle jet plugs easily i know, but the last time i took it all apart they were clear. I tested the mechanical fuel pump. One way valve and diaphram appear to do what you would expect. I tested the bystarter with 12 volts and it appears to be working. i did a compression test (cold because it wont run long enough to warm) 160 psi at all 3 cyl.

When it does run (always on the verge of stalling) i pulled the plugs. in all three cases there was an effect. So i know that i am getting some kind of spark in all 3 holes. Its like its running badly out of time. What have i missed? some sensor gone bad? timing belt looks perfect?

Any and all help would be appreciated.

Thank you
 
Might sound crazy but check and make sure the emergency stop is fully deactivated by the lanyard.
 
Do you have the service manual? Have you checked the timing marks? Your instincts may be accurate. They do jump time even when the belt looks ok.

You sound like you're pretty well versed on the carbs but I know how tricky the later edition Keihin carbs can be. I wouldn't rule fuel out until I knew it was something else for sure.

There's a guy here, Alan Hicks, that I would call the resident "multi carb guru" for this site. Hopefully he chimes in with his wisdom on the subject.

I know that he dislikes the by starter system and he has spoken often of the importance of keeping the tubing system arranged "just so" on these set ups.

Did you get your vent tubes put back EXACTLY as they came off? See items 1,2,3 and 4 in the link below.

Honda Outboard 30HP OEM Parts Diagram for Carburetor Tubing | Boats.net

Buy OEM Parts for Honda Outboard 30HP Carburetor Tubing Diagram
www.boats.net www.boats.net

Sorry, no cure but I think it helps to talk through a problem. It often helps the LIGHT BULB come on.

Good luck.
 
Thanks for the excellent feedback. i am confident all tubing was replaced correctly. I also ordered the idle jets as a precaution. Today i will confirm the timing by marks and i will manually add fuel while it runs to see if it alters the pattern.
 
Does anyone happen to have instructions for timing alignment for a bf30? i see all the marks but i am unsure what is my landmark for the flywheel T.
 
i believe i have confirmed timing is correct. By way of the alignment shown in the photos. Also confirmed no.1 piston is at top.

timing 1.jpg


timing2.jpg
 
i've checked every electrical connection now. It starts up everytime. But only half choke. Will idle there for about a minute then stalls. Happy to fire up again immediately to do the same thing. I half to revisit fueling because there seems to be not much else. If i disconnect the linkage and work it to increase the RPM it does increase and then surges back and forth until it finally stalls again. spraying fuel in the ventury has zero effect. I suppose it wouldnt if it is indeed flooding itself. Which is what i now consider.
 
If it runs at half choke it is probably flooding itself. I would suspect the CDI is weakening or has a bad ground if it runs for a few minutes and stalls out when the ignition demands a faster spark cycle.
 
Do CDI's weaken? i thought they worked or they didnt? i have been checking grounds etc. Ill try to find that one.
BTW checked the carbs again. all clear. The floats float and move freely.
 
Yes CDI's weaken they are basically a circuit board and are affected by heat and internal connection loss. It is quite common to have one work fine for a short time and then fail only to cool off in minutes and work again for a short time repetitively until failing completely.
 
I have never known a Honda CDI to weaken, they either work or they don't. Have you had the carbs apart since pulling out if storage, if not I would be revisiting them. Just one more thing to check before you do, try disconnecting the temp sensor, it could be putting the ecm into gaurdian. However, I am almost certain it 's a fuel issue, that's pretty much all that goes wrong with these engines
 
Wait a minute!

You previously posted "I tested the bystarter with 12 volts"

Now, you're saying it only starts at "half choke"....I don't understand that at all.

The bystarter that requires voltage to "turn off" cannot be set to "half choke". it has no manual control....it's "automatic"

The electric bystarter is ONLY used on outboards with electric starter and defaults to full on when the engine is cold.

So is this a pull start only engine then?
 
By choke i meant fast idle (partial throttle) at the control box. It electric start with power trim.
While i had the bystarter off, i just hooked a 12v battery to it and it warmed and extended around 3mm (1/8") in a few minutes.
ill try the suggestion regarding the temp sensor. Can anyone tell me how to check the ground to the cdi?
 
The more i think about it, the more it makes sense to me that my motor is in protection mode. It start instantly but stalls with the same consistency.
When i pull the plugs they are black which seems consistent with the cdi limiting spark despite all my encouragement. By disconnecting the temp sensor am i bypassing it? Or does that create a permanent danger call to the cdi?
 
Temp sensor is open circuit when temp is normal, therefore disconnecting it will make it redundant. Black sooty spark plugs is usually a very rich condition. Did you measure the float levels correctly. I still think this is a carb issue
 
update: With the temp sensor disconnect she does not stall. So i believe it is the cdi causing that. Maybe for good reason. Ive been running this thing on earmuffs that don't seal super well. The water coming out of the pee hole has always been underwelming. sometimes ill put a wire up there and the flow increases. Every time i pull the intake manifold there is alot of debris in the water ways. Sand and salt. Ive only got about 12 hours on her all fresh water. When i ran her today there was no pee. i had a new impeller kit so i put that in. Still no pee. So i pulled the therostat.
And put her in a tub. (This motor did not have a thermostat when it came to me). Still no pee and she's getting warm. Even the lowers. So it seems i have a cooling problem. It doesnt necessarily mean the temp gauge was correct. The motor never got warm in those trials cause she didnt run long enough.

Anyways i am encouraged that progress is finally being made thanks to this great forum. i suspect you might now tell me to pull the cooling jacket on the port side of the motor? One other thing: the new impeller was fricken stiff. like hard to get in there stiff. Made me wonder. Also direction of
blades i gave it a clockwise bias.

As always please chime in with your thoughts i am super greatful for any and all input.
 
Impeller will right itself when engine starts. If it has never been done I would definitely remove the water jacket for a clean out, especially the little slotted hole at the bottom, and replace the anode whilst you're in there.
 
Question on the internal waterways: if i plug a hose into the wash plug and pump water in should it reach the motor? I did this with the water jacket off and no water was present in the motor from the hose below. I did also run water directly into the thermostat orifice and that water did seem to work its way through. i am wondering if i have a blockage at the pipe from pump to motor?

coolant flush.jpg
 
Ok The cooling system has had a full service. Now she pees like a race horse. I have discovered that she is running on 2 cylinders at the most.
i made a video but its too big to upload. Its basically running on cylinder 3. Not at all on cylinder 1 and only partially on cylinder 2. That is to say pulling plug wire 1 makes no difference. pulling plug wire 2 makes little difference. but when i pull 3 she keep running barely. So i suspect that cylinder 2 is doing something. I am starting starting to suspect the cdi as someone had suggested. Again thoughts are appreciated.
 
Have you synchronised carbs, don't jump to conclusions, you will spend money for nothing. Anyway, one cylinder out can also be a trigger coil or ignition coil. My guess without looking at your engine is fuel related. If you don't know how to diagnose a simple engine like this then it would be way cheaper to get a pressional to look. I see so much money wasted on this forum due to online diagnosis.If the engine is running, when you pull the plug cap off and hold it 1/2" away you should hear the spark clearly, if you can, then believe me, the ignition system is fine.
 
Mr Ian you are correct. (again) I switched the coils around to check them. But number one was still the bad one. So then i started to consider your thoughts on fuel delivery. And then i got a call that my idle jets were in. So i put new jets in 1 and 2 and the difference is major. She's not 100% but we are clearly on the right track now. To be clear. The temp guage is fubar and she still wont run with it connected. So that caused alot of confusion here.
But now that i know she's getting coolant and i can keep her running, Its now possible to diagnose. After adjusting the idle screw she will now idle. And she will spin up to 4k or so without much effort but it doesn't yet sound 100% right so i will source an appropriate sync gauge and tackle that next.

My thought on the fuel issue is that it may have been the o-rings on the idle jets. I looked at the jets under magnification and there were no cracks and the passages were clear. but the new jets make an undeniable difference so who knows. One thing for sure it was an issue of too much fuel.
Every thing is black. The tub water. The back of the motor. She was uber rich!.

On a side note the issue with the water pump is that the shaft key ejected during assembly. So make sure you see it find home when you put the housing on the shaft. After several attempts i resorted to the original key with success. A worthy exercise to know what is now flowing end to end.

If you have any more thought on tuning the pesky Kiehin cans i'd love to hear them.

D.
 
Balancing carbs is vital and should be done with a set of vacuum gauges. I also suggest you check that the enrichment element needle is in the fuel tube and not pushed over to one side allowing a rich uncontrolled fuel flow.Set your air screws to 2 1/4 turns and tune as per manual.
 
Vacuum gauge ordered. My honda carb manual says 3 turns for the bf30. Do you recommend i remove the limit caps to check them prior to the balancing? if so heat is the secret?
 
No, I very carefully drill a small hole in the centre, then pry them out with a pick
Then with the engine warm and idling, I turn the screw in until a missfire is noted, screw out slowly until that cyl fires again, then an extra half a turn from there. Do this on all cylinders after balancing and you'll find she runs very smoothly. The original factory screw settings are usually to lean and you can't get her to idle sweetly
 
So my next question is do i risk messing with those caps or just adjust to the best option with them in place. Which allows me less than 1/4 turn of adjustment. i would like to settle that before i do the balancing. moving them within the limit cap allowance make little difference if any.

Since i have to wait a week for a new temp sensor i decided to test this one. There is plenty of good info test resistance while bathing it in a know water temp. And according to those tests the unit is good. So i began to wonder if the whole temp sensor issue was a phantom. But its not.
The motor now runs on all cylinders and will idle once warm without fail. Plug the sensor back in and she will stall within a minute. Every time.

I also checked the connection from the sensor to cdi. Its spotless and well connected. As is every connection i have investigated on this power unit.


Makes no sense.
 
Just wrap up this thread. There were 2 things wrong with the BF30. The temp sensor was bad. Even though all the common volt meter test said it wasn't. i finally replaced it this week and the boat no longer stalls after a minute. The second thing was the idle jets in 2 carbs. Even though they looked fine even under magnification. Once replaced made an immediate and lasting improvement. Sea trials new week. Too bad summer is over.
Hopefully this will help someone avoid some of my frustration. And i would still be at it if not for this forum. Thank you.
 
Back
Top