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Honda BF9.9A (4 stroke) Fuel not reaching compression chamber

S

Surfing fish

New member
Hello,
I am trying to get this old pull start outboard engine running again, I have no idea how long it has been sitting (at least 5 years). I have fully disassembled the carborator and it is clean. The fuel made it to the caraborator and into the next section where it splits the fuel intake to the 2 cylinders. However, the spark plugs are bone dry. I would figure if fuel was making its way into the chamber the plugs will have some gas on them when turned over without the coils attached. also, I haven't been able to get the spark plugs to spark but they might need to be replaced. any ideas? Thanks
 
Post actual compression values here----Have you checked-valve clearance?----Belt timing correct.-----Check spark at night-or in the dark.-----Or put 6 drops of fuel in each plug hole and pull cord 10 times and report the results.
 
Thank you for the quick response. valve clearance is .004in, belt timing is correct. I can't really check spark plugs in the dark right now but I took a voltmeter to the coils and got .004v on both no amps. I tried injecting fuel into the plug holes, and nothing happened after the 10 pulls, I am thinking the coils are bad or I am not getting enough current off the flywheel.
 
Hi

Do you know what year or have the frame number?

Is your kill/stop switch working right? It should NOT be grounded.

Is the advancer (pulser coil) making voltage? About 4 to 5 vac from the wire under the cam pulley to the CDI box.
It won't fire the coil if not.

You can throw a blanket over your head and the outboard to create darkness. Done it myself.
Having a helper makes it easier for sure.


I believe that the exciter coil should be making about 100 vac or more on the wire to the CDI box for starting. That might look like 50 vac on a multimeter if you don't have a DVA. No idea what amps should be but probably a very small milliamp number.

Is the green oil lamp coming on when you crank it? The exciter coil powers that too if enough oil pressure builds to close the pressure switch..(about 3 psi I think) Again, a blanket makes it dark enough to see.

When you cleaned the carb did you remove the low speed tube and make sure that tiny oring is still good? It's best to use a new oring and install it very carefully since it is CRITICAL that the tube is clean and it seals at the top of the carb throat. See items 1 and 11 in the link:



Good luck.
 
The engine should have responded / barked like a wild dog.----So you have no spark or spark at the wrong time.----And switching plug leads does nothing on the small 4 strokes.
 
Forgot to mention that, since this is a "waste spark" ignition where both plugs fire together every time, you should leave one plug still connected to the coil when testing the other for spark.
 
Thank you, The kill switch wire was disconnected. When I reconnect it I was getting about 18v 8mA on the exciter coil and about 1.5v 3mA on the spark plug coil. The green oil light hasn't turned on

When I cleaned the carb I checked the orings and cleaned any gunk that was in the carb.
 
Those voltage readings look pretty low. Are you using the AC volts scale on your meter?

Did you try checking the pulser coil voltage? Again, 1/2 wave ac volts.

On stored motors, rust can form and critters can build nests. Mud dauber wasps can coat surfaces of the flywheel magnets and coil core feet and keep the magnets from making full power.
If rust builds up under the flywheel it can cause "jacking" and dislodge or move the components enough to affect the air gaps in there.

The pulser cavity area underneath the cam pulley can have dirt, debris and water accumulate and disrupt the generating capacity too.
 
Ok, so I tested the spark plugs on another engine that I know runs and both plugs work, I decided that I would try to run the flywheel off a cordless drill and that worked wonders, no more pulling! The flywheel does have some rust on the magnets however, when I run the flywheel with the drill I can see visible sparks jumping from the sparkplug cord in-between the ignition coil and spark plug to the motor housing, so those need to be replaced. and I assume if the spark can jump 3-4 mm through the rubber insulation it can light off the spark plug

I also switch to an older multimeter and was getting about 150v at the plugs.

I even with the drill I still can't get a good mist of fuel in the chamber the plugs still are dry, is there a way to adjust fuel flow on the caraborator besides the air intake and choke? Thank you
 
Yeah, if spark jumps from the plug wires, change them!

Aa far as the carb goes, you may not have cleaned it as well as you think you did.

Does the primer bulb get hard and does fuel come out of the float chamber drain if you back out the drain screw a couple of turns?

If so, I have suggestions about how to use carb spray to get that thing cleaned. Carburetors operate MOSTLY on air pressure and air movement to make gas flow.
That is often overlooked in the cleaning process.

That should be a BG model carburetor. Look at the stamping on the body. Make sure it is a BG and no one has put an "Amazon Special" on it. They don't always work so great.

IF it's the original carb, it should have a "limiter cap" over the mixture adjustment screw. You'll probably need to remove that to check and clean that circuit You have to carefully drill a small hole in the cap to use a screw or pick tool to pull it off. It's glued in so a little heat from a soldering iron helps.

More later. That is, if you want it.
 
If that one has a limiter cap and you try to remove it, you might break off the top of the mixture screw. It was made to snap off (thank you American politicians and "air police")
If it breaks, you have use a SHARP pick tool to stab the edge of the screw head that's there and work it around counter clockwise to get it unscrewed.

BUT...
the oring acts as a lock to hold it in there. You have to turn the screw TWICE as much as you think it takes to disengage the threads THEN turn it a little more to be sure. Because, once the threads are backed out, you still need to pry the dang thing out against the force of the oring!
It's a TOTAL PAIN! But it's the ONLY way to clean out that low speed circuit completely.
Once it's out, you can cut a slot in the screw head if you want/need to reuse the screw for adjustment.
 
Hopefully it doesn't have a limiter and you can just remove the mixture screw and blast carb spray in there.

There are two holes on the forward flange of the carb body that aren't bolt holes. Those are the AIR JET passages. Those can get plugged and need to be blasted with carb spray. The carb won't move enough fuel if those are clogged.

It's best to have float valve, vmixture screw and emulsion tubes removed when spraying/cleaning.

There are atmospheric vents inside the top of the float chamber. Right and left. The holes are pretty tiny so look carefully. Make sure those will pass carb spray to the outside of the top of the carb. Without atmospheric pressure pushing down on the fuel in the float chamber, fuel won't flow very well.

At the top of the carb throat, on the engine side, there are several very tiny holes. You can only see one with the throttle closed but you can see them all if you prop the throttle wide open.

Use the plastic straw that comes with the carb spray to flush out EVERY ONE of those little holes. Do it more than once. I call that backflushing and it's important.

Lastly there's that little slow jet inside the little skinny emulsion tube. The one with the oring at the top. The jet is INSIDE that skinny little tube and it's very hard to tell if it's clean or clogged. If it's clogged, the engine might not ever start.
I used to replace those tubes because they're such a B|t(h to get clean. But now, they're mostly "unavailable" so you MUST get that internal jet clean.

Also, be very careful when tightening the plug that holds the tubes at the bottom. If you tighten it too much you can Crack the tube.

Same thing about bottoming out the mixture screw. Too tight ruins the screw taper and seat.
Be gentle!

Good luck.
 
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