Johnson outboard bogs down [Repost]
 

[I've reposted this in hopes it was missed due to various disagreements
taking up everyone's attention the first time]

My son has a circa 1985 Johnson 70 HP two-stroke outboard motor. It ran well
until recently when it began "bogging down" when the throttle/shifter is
pushed full forward. Now, I'm no boating expert, so anything I say comes
from the viewpoint of a mechanic in another field and is subject to scrutiny
from those knowledgeable on power boating.

This is a 3 cylinder in-line outboard that my son got second-hand, so
there's no manuals to which we can refer. We did notice that when either of
the "lower" two plug wires were pulled the motor almost stalls but pulling
the "top" plug wire did nothing. So, we tried switching the coil paks for
the top two cylinders to see if the problem would "move" but that did
nothing to solve the problem.

Next we pulled the top carb and took it apart. I noticed the float bowl was
dry and the float needle was stuck closed. I was elated thinking this was
the solution and disassembled the float to clean the fuel varnish from the
needle and seat. I should mention that he confessed he hadn't sprayed some
sort of protective solution into the carbs when he stored it for the winter
and that that was probably the reason. Since the other two cylinders weren't
giving any apparent problems we didn't screw with them, we just re-assembled
the motor and took it out for a test. It ran ok for a few "starts" but then
returned to the same "bogging" problem when goosed.

He's played with the remote throttle adjustors with a little success, but
the problem still remains. He's also emptied the fuel tanks and added fresh
fuel.

There doesn't seem to be a way to adjust the fuel/air mixture on these
carbs, so we haven't been able to screw that up in any way, as far as I
know. The last thing we tried was removing the lower two carbs to
disassemble and clean them, but the problem persists. The linkage that
synchronizes the throttle to the carbs is pretty solid so we don't think we
screwed that up.

Also, the plate that I assume holds the pick-up coils for the magneto (or
which trigger an electronic ignition) seems to advance all the way as soon
as the throttle is moved up a little. That may be normal, I'm not sure, but
we don't know how to adjust it properly. I've looked for shorts in the
ignition system as far as I'm able without major disassembly and everything
looks ok. My next move was to pull off the flywheel which I assume must
contain a magnet(s) to trigger some sort of induction coils on that plate I
mentioned to see if there was something amiss under there, but we didn't
have anything big enough in my little service tool kit for that.

It seems to be one of those problems where almost anything you do "cures" it
for a short while and the motor runs beautifully. Then at some point, when
you go to take off the darn thing bogs down and almost stalls. He can get
going by exercising the throttle/shifter lever rapidly a few times and then
"babying" it into high speed. Once it gets going it runs fine at high speed.

If anyone has any suggestions I'd be very open to them, or perhaps a link to
somewhere with instructions for setting the throttle cables, fuel mixture
and/or timing. I've looked without any success. Sorry about the length of
this post but I wanted to include as much pertinent info as possible. If
I've left needed info out let me know and I'll try to get it.

Johnson outboard bogs down [Repost]
 

On Sat, 28 Jun 2008 10:24:30 -0400, "dvus"
wrote:

[I've reposted this in hopes it was missed due to various disagreements
taking up everyone's attention the first time]

My son has a circa 1985 Johnson 70 HP two-stroke outboard motor. It ran well
until recently when it began "bogging down" when the throttle/shifter is
pushed full forward. Now, I'm no boating expert, so anything I say comes
from the viewpoint of a mechanic in another field and is subject to scrutiny
from those knowledgeable on power boating.

This is a 3 cylinder in-line outboard that my son got second-hand, so
there's no manuals to which we can refer. We did notice that when either of
the "lower" two plug wires were pulled the motor almost stalls but pulling
the "top" plug wire did nothing. So, we tried switching the coil paks for
the top two cylinders to see if the problem would "move" but that did
nothing to solve the problem.

Next we pulled the top carb and took it apart. I noticed the float bowl was
dry and the float needle was stuck closed. I was elated thinking this was
the solution and disassembled the float to clean the fuel varnish from the
needle and seat. I should mention that he confessed he hadn't sprayed some
sort of protective solution into the carbs when he stored it for the winter
and that that was probably the reason. Since the other two cylinders weren't
giving any apparent problems we didn't screw with them, we just re-assembled
the motor and took it out for a test. It ran ok for a few "starts" but then
returned to the same "bogging" problem when goosed.

He's played with the remote throttle adjustors with a little success, but
the problem still remains. He's also emptied the fuel tanks and added fresh
fuel.

There doesn't seem to be a way to adjust the fuel/air mixture on these
carbs, so we haven't been able to screw that up in any way, as far as I
know. The last thing we tried was removing the lower two carbs to
disassemble and clean them, but the problem persists. The linkage that
synchronizes the throttle to the carbs is pretty solid so we don't think we
screwed that up.

Also, the plate that I assume holds the pick-up coils for the magneto (or
which trigger an electronic ignition) seems to advance all the way as soon
as the throttle is moved up a little. That may be normal, I'm not sure, but
we don't know how to adjust it properly. I've looked for shorts in the
ignition system as far as I'm able without major disassembly and everything
looks ok. My next move was to pull off the flywheel which I assume must
contain a magnet(s) to trigger some sort of induction coils on that plate I
mentioned to see if there was something amiss under there, but we didn't
have anything big enough in my little service tool kit for that.

It seems to be one of those problems where almost anything you do "cures" it
for a short while and the motor runs beautifully. Then at some point, when
you go to take off the darn thing bogs down and almost stalls. He can get
going by exercising the throttle/shifter lever rapidly a few times and then
"babying" it into high speed. Once it gets going it runs fine at high speed.

If anyone has any suggestions I'd be very open to them, or perhaps a link to
somewhere with instructions for setting the throttle cables, fuel mixture
and/or timing. I've looked without any success. Sorry about the length of
this post but I wanted to include as much pertinent info as possible. If
I've left needed info out let me know and I'll try to get it.

From an automotive engine/carb standpoint two things come to mind, and
I've experienced both causing bogging.
1. carb accelerator pump.
2. distributor advance.
This is all aside from proper timing which is checked first.
A dwellmeter, timing light and good timing marks get that right.
Sorry I don't know your engine or where to get a manual.
Maybe jamesganc(sp?) or gfretwell have some advice, as they appear to
have actual experience working on OB's.

--Vic

Johnson outboard bogs down [Repost]
 

On Jun 28, 10:24*am, "dvus" wrote:
[I've reposted this in hopes it was missed due to various disagreements
taking up everyone's attention the first time]

My son has a circa 1985 Johnson 70 HP two-stroke outboard motor. It ran well
until recently when it began "bogging down" when the throttle/shifter is
pushed full forward. Now, I'm no boating expert, so anything I say comes
from the viewpoint of a mechanic in another field and is subject to scrutiny
from those knowledgeable on power boating.

This is a 3 cylinder in-line outboard that my son got second-hand, so
there's no manuals to which we can refer. We did notice that when either of
the "lower" two plug wires were pulled the motor almost stalls but pulling
the "top" plug wire did nothing. So, we tried switching the coil paks for
the top two cylinders to see if the problem would "move" but that did
nothing to solve the problem.

Next we pulled the top carb and took it apart. I noticed the float bowl was
dry and the float needle was stuck closed. I was elated thinking this was
the solution and disassembled the float to clean the fuel varnish from the
needle and seat. I should mention that he confessed he hadn't sprayed some
sort of protective solution into the carbs when he stored it for the winter
and that that was probably the reason. Since the other two cylinders weren't
giving any apparent problems we didn't screw with them, we just re-assembled
the motor and took it out for a test. It ran ok for a few "starts" but then
returned to the same "bogging" problem when goosed.

He's played with the remote throttle adjustors with a little success, but
the problem still remains. He's also emptied the fuel tanks and added fresh
fuel.

There doesn't seem to be a way to adjust the fuel/air mixture on these
carbs, so we haven't been able to screw that up in any way, as far as I
know. The last thing we tried was removing the lower two carbs to
disassemble and clean them, but the problem persists. The linkage that
synchronizes the throttle to the carbs is pretty solid so we don't think we
screwed that up.

Also, the plate that I assume holds the pick-up coils for the magneto (or
which trigger an electronic ignition) seems to advance all the way as soon
as the throttle is moved up a little. That may be normal, I'm not sure, but
we don't know how to adjust it properly. I've looked for shorts in the
ignition system as far as I'm able without major disassembly and everything
looks ok. My next move was to pull off the flywheel which I assume must
contain a magnet(s) to trigger some sort of induction coils on that plate I
mentioned to see if there was something amiss under there, but we didn't
have anything big enough in my little service tool kit for that.

It seems to be one of those problems where almost anything you do "cures" it
for a short while and the motor runs beautifully. Then at some point, when
you go to take off the darn thing bogs down and almost stalls. He can get
going by exercising the throttle/shifter lever rapidly a few times and then
"babying" it into high speed. Once it gets going it runs fine at high speed.

If anyone has any suggestions I'd be very open to them, or perhaps a link to
somewhere with instructions for setting the throttle cables, fuel mixture
and/or timing. I've looked without any success. Sorry about the length of
this post but I wanted to include as much pertinent info as possible. If
I've left needed info out let me know and I'll try to get it.

Get a manual and rebuild the carbs correctly. There are tiny passages
in there that need to be cleaned well, I use thin wire. After a good
disassembly and cleaning the floats need to be adjusted properly.

Johnson outboard bogs down [Repost]
 

On Sat, 28 Jun 2008 10:24:30 -0400, "dvus"
wrote:

If anyone has any suggestions I'd be very open to them, or perhaps a link to
somewhere with instructions for setting the throttle cables, fuel mixture
and/or timing. I've looked without any success. Sorry about the length of
this post but I wanted to include as much pertinent info as possible. If
I've left needed info out let me know and I'll try to get it.

This might seem like an odd question, but have you pulled the plugs
and looked at them? Or better yet- change them?

Johnson outboard bogs down [Repost]
 

If you have an engine with a problem rule 1 is not to touch/modify anything
that does not have a problem. You have a 3-cylinder running on 2 cylinders; so
don't touch anything that's specific to the 2 cylinders that are working.
Meddling with the carbs of these 2 cylinders was a bad idea. Violating this
rule could easily leave you with umpteen intermixed selfinflicted problems,
that cannot be solved by anyone but a high-paid expert.
If you have a 3-cylinder running on 2 cylinders do not touch/modify anything
these 3 cylinders have in common; if 2 cylinders run with the current
ignition-timing and carburettor settings 3 cylinders should do the same
(fine-tuning comes later when all 3 are running roughly the same).
Be carefull when this is an old engine running on 2-stroke mixed gasoline;
when a cylinder gets no fuel it gets no oil. Crank-bearings and
cylinder/piston/pistonrings might already have been damaged; check this
cylinder for compression as a quick and dirty way to estimate engine damage.
When it is a modern engine with oil-injection, the third cylinder might be
soaked in oil; so get a new sparkplug, use it outside the combustionchamber to
check that there is a solid spark, and get the old sparkplug out.
If the old sparkplug is soaked in oil, try to smell if there is a strong
gasoline smell with it. If not, your repair of the carburetter failed; repeat
the repair and make sure it fills this time and check wether the jets are not
clogged up in the same way and with the same residue as the rest of the
carburettor was.
If the 3rd cylinder gets oil AND gasoline the cumulated oil from your earlier
attempts to start it without fuel probably got the sparkplug so dirty that
replacing it with a new one is the only quick solution.
When this fails check compression too. Failure to prepare the engine for the
winter stop might result in "hung" piston rings; you can try a strong
commercial engine cleaner (for internal cleaning!) here, to avoid a
cylinderhead pulling with risks for further damage (broken pistonrings or
worse).
After that get it to an outboard expert.

Mees de Roo

Johnson outboard bogs down [Repost]
 

dvus wrote:
[I've reposted this in hopes it was missed due to various disagreements
taking up everyone's attention the first time]

My son has a circa 1985 Johnson 70 HP two-stroke outboard motor. It ran
well
until recently when it began "bogging down" when the throttle/shifter is
pushed full forward. Now, I'm no boating expert, so anything I say comes
from the viewpoint of a mechanic in another field and is subject to
scrutiny
from those knowledgeable on power boating.

This is a 3 cylinder in-line outboard that my son got second-hand, so
there's no manuals to which we can refer. We did notice that when either of
the "lower" two plug wires were pulled the motor almost stalls but pulling
the "top" plug wire did nothing. So, we tried switching the coil paks for
the top two cylinders to see if the problem would "move" but that did
nothing to solve the problem.

Next we pulled the top carb and took it apart. I noticed the float bowl was
dry and the float needle was stuck closed. I was elated thinking this was
the solution and disassembled the float to clean the fuel varnish from the
needle and seat. I should mention that he confessed he hadn't sprayed some
sort of protective solution into the carbs when he stored it for the winter
and that that was probably the reason. Since the other two cylinders
weren't
giving any apparent problems we didn't screw with them, we just
re-assembled
the motor and took it out for a test. It ran ok for a few "starts" but then
returned to the same "bogging" problem when goosed.

He's played with the remote throttle adjustors with a little success, but
the problem still remains. He's also emptied the fuel tanks and added fresh
fuel.

There doesn't seem to be a way to adjust the fuel/air mixture on these
carbs, so we haven't been able to screw that up in any way, as far as I
know. The last thing we tried was removing the lower two carbs to
disassemble and clean them, but the problem persists. The linkage that
synchronizes the throttle to the carbs is pretty solid so we don't think we
screwed that up.

Also, the plate that I assume holds the pick-up coils for the magneto (or
which trigger an electronic ignition) seems to advance all the way as soon
as the throttle is moved up a little. That may be normal, I'm not sure, but
we don't know how to adjust it properly. I've looked for shorts in the
ignition system as far as I'm able without major disassembly and everything
looks ok. My next move was to pull off the flywheel which I assume must
contain a magnet(s) to trigger some sort of induction coils on that plate I
mentioned to see if there was something amiss under there, but we didn't
have anything big enough in my little service tool kit for that.

It seems to be one of those problems where almost anything you do
"cures" it
for a short while and the motor runs beautifully. Then at some point, when
you go to take off the darn thing bogs down and almost stalls. He can get
going by exercising the throttle/shifter lever rapidly a few times and then
"babying" it into high speed. Once it gets going it runs fine at high
speed.

If anyone has any suggestions I'd be very open to them, or perhaps a
link to
somewhere with instructions for setting the throttle cables, fuel mixture
and/or timing. I've looked without any success. Sorry about the length of
this post but I wanted to include as much pertinent info as possible. If
I've left needed info out let me know and I'll try to get it.


Could be the stator - big bucks...

Johnson outboard bogs down [Repost]
 

On Sun, 29 Jun 2008 00:42:39 +0200, "Mees de Roo"
d wrote:

If you have an engine with a problem rule 1 is not to touch/modify anything
that does not have a problem. You have a 3-cylinder running on 2 cylinders; so
don't touch anything that's specific to the 2 cylinders that are working.
Meddling with the carbs of these 2 cylinders was a bad idea. Violating this
rule could easily leave you with umpteen intermixed selfinflicted problems,
that cannot be solved by anyone but a high-paid expert.
If you have a 3-cylinder running on 2 cylinders do not touch/modify anything
these 3 cylinders have in common; if 2 cylinders run with the current
ignition-timing and carburettor settings 3 cylinders should do the same
(fine-tuning comes later when all 3 are running roughly the same).
Be carefull when this is an old engine running on 2-stroke mixed gasoline;
when a cylinder gets no fuel it gets no oil. Crank-bearings and
cylinder/piston/pistonrings might already have been damaged; check this
cylinder for compression as a quick and dirty way to estimate engine damage.
When it is a modern engine with oil-injection, the third cylinder might be
soaked in oil; so get a new sparkplug, use it outside the combustionchamber to
check that there is a solid spark, and get the old sparkplug out.
If the old sparkplug is soaked in oil, try to smell if there is a strong
gasoline smell with it. If not, your repair of the carburetter failed; repeat
the repair and make sure it fills this time and check wether the jets are not
clogged up in the same way and with the same residue as the rest of the
carburettor was.
If the 3rd cylinder gets oil AND gasoline the cumulated oil from your earlier
attempts to start it without fuel probably got the sparkplug so dirty that
replacing it with a new one is the only quick solution.
When this fails check compression too. Failure to prepare the engine for the
winter stop might result in "hung" piston rings; you can try a strong
commercial engine cleaner (for internal cleaning!) here, to avoid a
cylinderhead pulling with risks for further damage (broken pistonrings or
worse).
After that get it to an outboard expert.

Mees de Roo


Mees, in what part of the Netherlands do you live?

Johnson outboard bogs down [Repost]
 

Mees, in what part of the Netherlands do you live?
IJmuiden

Johnson outboard bogs down [Repost]
 

On Sun, 29 Jun 2008 12:53:38 +0200, "Mees de Roo"
d wrote:

IJmuiden

You are definitely close to the sea!

I have good friends in Stolwijk, just south of Gouda.

It is good to hear from you.

Johnson outboard bogs down [Repost]
 

dvus wrote:

[snip original post]

Thanks to everyone who responded, all comments have been committed to
printer for reference as we slog through this problem. If we find some
defining cause/solution to this situation I'll post it here.

Thanks again.

--
dvus

Johnson outboard bogs down [Repost]
 

IJmuiden

You are definitely close to the sea!

Ran until recently a (westerly) nomad from the marina. Am now looking for a
warwick - those few inches make a difference of ? 300 ($ 450) a year.
Good sailing for a solid boat from here.