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Throttle response slow 8hp

M

merc200dalarna

Contributing Member
When cold I can't move the throttle reasonably fast without stalling out the motor. It immediately dies.
("Cold" is after it runs without choke, maybe like 3 minutes into running)
Is that common on honda? Any gesses what it is?

When fully warm it's better but not fully OK, it is still very sensitive to fast throttle.

Thankful to any advice since the company that sold it to me says its just when cold, but it's not.
 
What is the serial number for your motor?

There are a couple of different models of 8 HP and each has its own design to aid in accelerating.

Either one does have to be fully warmed up to idle and accelerate correctly.

Mike
 
hondadude said:
What is the serial number for your motor?

There are a couple of different models of 8 HP and each has its own design to aid in accelerating.

Either one does have to be fully warmed up to idle and accelerate correctly.

Mike
Click to expand...
BEAAJ 1005614 is the numbers on the transom bracket (or whatever its called) (different numbers inside)
It has the carb with "accelerated" or "assisted" throttle. Don't know the name for that lever that "multiplies" throttle movement.
 
While it's very likely the issue IS carb related, it occurred to me while reading your post, that I've had a few of the BF8D outboards in my rental fleet exhibit similar symptoms and it ended up being a desd cylinder.

These little Honda twins will start and run SURPRISINGLY well on only one cylinder! Of course, they will be down on power and hesitate when accelerated but can be so "smooth" that I know I've been fooled by them at first.

So, I just thought I would mention it and a quick and easy cylinder drop out test would confirm or eliminate the possibility. That is if you haven't done it already.

Good luck.
 
jgmo said:
While it's very likely the issue IS carb related, it occurred to me while reading your post, that I've had a few of the BF8D outboards in my rental fleet exhibit similar symptoms and it ended up being a desd cylinder.

These little Honda twins will start and run SURPRISINGLY well on only one cylinder! Of course, they will be down on power and hesitate when accelerated but can be so "smooth" that I know I've been fooled by them at first.

So, I just thought I would mention it and a quick and easy cylinder drop out test would confirm or eliminate the possibility. That is if you haven't done it already.

Good luck.
Click to expand...
That would surprise me too, because it runs as you say very smooth.
OK, so I'm no mechanic, but "drop out test" is when you pull one sparkplug (cap) at a time while it runs?
 
Yes! Exactly! Raise the idle about 4 or 500 rpm and lock the throttle. Pull a plug wire and see what happens. If it is running on only one cylinder, if you happen to pull the wire to the running one, the engine will stop immediately. If you pull the wire to the dead cylinder, there will be absolutely no change.

And, while this isn't the best way to do a "cylinder contribution" test, it could also tell you something about an engine that has BOTH cylinders firing. If you pull the wire to the top cylinder, for example, and take note how the engine sounds and how much the rpms drop off.....the sound and rpm drop should be pretty much equal when you pull the wire to the bottom cylinder and leave the top connected.

The effect won't be identical but there should be no large discernible discrepancy between the two. If there is a noticeable difference in run quality of one to the other, then the lesser cylinder may not be contributing as well as it should for some reason. This might be due to a worn spark plug, a valve adjustment problem or some other mechanical issue and should ultimately be investigated.

But, for now, we are just interested in knowing if both cylinders are firing.

Good luck.

PS...This chore is easier to do if you first disconnect each spark plug boot with the engine off and smear a small amount of DIELECTRIC (tune up) grease on the inside of the boot. Sometimes spark plug boots will stick hard to the plug enamel and make it difficult to pull them off.

Also, make sure you protect yourself from getting shocked from a leaking wire or boot by using a DRY rag or even an insulated pair of pliers to handle the spark plug boot. There are specialty pliers for doing this sold at most auto parts stores but a pair of regular needle nose held in a DRY shop towel or rag will work ok as long as you take care not to damage the wire or boot by pulling too hard with the hard jaws. The "pregrease" technique listed above will aid in doing this without damage.

Good luck.
 
Last edited:
jgmo said:
Yes! Exactly! Raise the idle about 4 or 500 rpm and lock the throttle. Pull a plug wire and see what happens. If it is running on only one cylinder, if you happen to pull the wire to the running one, the engine will stop immediately. If you pull the wire to the dead cylinder, there will be absolutely no change.

And, while this isn't the best way to do a "cylinder contribution" test, it could also tell you something about an engine that has BOTH cylinders firing. If you pull the wire to the top cylinder, for example, and take note how the engine sounds and how much the rpms drop off.....the sound and rpm drop should be pretty much equal when you pull the wire to the bottom cylinder and leave the top connected.

The effect won't be identical but there should be no large discernible discrepancy between the two. If there is a noticeable difference in run quality of one to the other, then the lesser cylinder may not be contributing as well as it should for some reason. This might be due to a worn spark plug, a valve adjustment problem or some other mechanical issue and should ultimately be investigated.

But, for now, we are just interested in knowing if both cylinders are firing.

Good luck.

PS...This chore is easier to do if you first disconnect each spark plug boot with the engine off and smear a small amount of DIELECTRIC (tune up) grease on the inside of the boot. Sometimes spark plug boots will stick hard to the plug enamel and make it difficult to pull them off.

Also, make sure you protect yourself from getting shocked from a leaking wire or boot by using a DRY rag or even an insulated pair of pliers to handle the spark plug boot. There are specialty pliers for doing this sold at most auto parts stores but a pair of regular needle nose held in a DRY shop towel or rag will work ok as long as you take care not to damage the wire or boot by pulling too hard with the hard jaws. The "pregrease" technique listed above will aid in doing this without damage.

Good luck.
Click to expand...
Sounds like I could do all that,and the honda plug-boots have such nice "handle" to grip hold of.
It will be day or two Before I can test it, I'm about to launch my lil boat, so I will do it then.
will be back with update
 
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