I just rebuilt the carburetor on my 3.0 liter mercruiser because the
engine was running rough. Well I rebuilt it very meticulously because
this was my first time rebuilding it and I thought everything went
well. Now the engine is running smoother and not flooding but the
problem is that after 3/4 throttle the carburetor starts to bog. It
runs great up until 3/4 throttle but after that it starts to bog, not
a serious bog, more like advancing the throttle isn't making any
difference. Well this wouldn't bother me because I never go that fast
anyway but since it is only a 4 cylinder I need that power to get on
plane with people in the boat as the boat is really struggling right
now. So if anyone has any ideas on what would cause this I would
appreciate it. I am assuming it is the carburetor because I didn't
have this problem until I rebuilt it. Thanks.

"JamesE" wrote in message
oups.com...
I just rebuilt the carburetor on my 3.0 liter mercruiser because the
engine was running rough. Well I rebuilt it very meticulously because
this was my first time rebuilding it and I thought everything went
well. Now the engine is running smoother and not flooding but the
problem is that after 3/4 throttle the carburetor starts to bog. It
runs great up until 3/4 throttle but after that it starts to bog, not
a serious bog, more like advancing the throttle isn't making any
difference. Well this wouldn't bother me because I never go that fast
anyway but since it is only a 4 cylinder I need that power to get on
plane with people in the boat as the boat is really struggling right
now. So if anyone has any ideas on what would cause this I would
appreciate it. I am assuming it is the carburetor because I didn't
have this problem until I rebuilt it. Thanks.


Sounds like running lean. Check the float adjustment.

You pooched the power valve installation or the float level is too low.
JR
JamesE wrote:
I just rebuilt the carburetor on my 3.0 liter mercruiser because the
engine was running rough. Well I rebuilt it very meticulously because
this was my first time rebuilding it and I thought everything went
well. Now the engine is running smoother and not flooding but the
problem is that after 3/4 throttle the carburetor starts to bog. It
runs great up until 3/4 throttle but after that it starts to bog, not
a serious bog, more like advancing the throttle isn't making any
difference. Well this wouldn't bother me because I never go that fast
anyway but since it is only a 4 cylinder I need that power to get on
plane with people in the boat as the boat is really struggling right
now. So if anyone has any ideas on what would cause this I would
appreciate it. I am assuming it is the carburetor because I didn't
have this problem until I rebuilt it. Thanks.



--
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth

I must have checked the float level 10 times before I put it back
together. Of course I could be measuring it wrong however. On my
rebuild kit it had a note that said that with four cylinder engines
experiencing rough idle and flooding that it may be necessary to
change to a spring loaded needle. So I changed it from the original
solid needle to the spring needle and then readjusted the float
level. Could this be causing the problem? Also you mentioned that I
could have put in the power valve wrong. What could have gone wrong
with it? I just put the gasket on and screwed it in. Was there
something else I should have done? Thanks, James.

I'd go back to the original needle even though the spring one should work.
It may be it changes how you should adjust the float. A low float could
cause this. There is nothing else to do for the power valve. Did a new
power valve come with the kit? If it did then I'd try the old one just to
see if that changes anything. Also does the carb have a small filter at the
inlet? If so check that as well for being in in the correct direction.

"JamesE" wrote in message
ups.com...
I must have checked the float level 10 times before I put it back
together. Of course I could be measuring it wrong however. On my
rebuild kit it had a note that said that with four cylinder engines
experiencing rough idle and flooding that it may be necessary to
change to a spring loaded needle. So I changed it from the original
solid needle to the spring needle and then readjusted the float
level. Could this be causing the problem? Also you mentioned that I
could have put in the power valve wrong. What could have gone wrong
with it? I just put the gasket on and screwed it in. Was there
something else I should have done? Thanks, James.

On Sep 7, 7:28 am, JamesE wrote:
I must have checked the float level 10 times before I put it back
together. Of course I could be measuring it wrong however. On my
rebuild kit it had a note that said that with four cylinder engines
experiencing rough idle and flooding that it may be necessary to
change to a spring loaded needle. So I changed it from the original
solid needle to the spring needle and then readjusted the float
level. Could this be causing the problem? Also you mentioned that I
could have put in the power valve wrong. What could have gone wrong
with it? I just put the gasket on and screwed it in. Was there
something else I should have done? Thanks, James.

One other thought I had is did you make sure that full throttle at the
controls is really opening the carb plates all the way?

Also check your accellerator pump for proper adjustment and function.

Does it always bog no matter how slowly you advance the throttle? If
it bogs even when opening the throttle slowly that does suggest a main
jet issue.

jamesgangnc wrote:
did you make sure that full throttle at the
controls is really opening the carb plates all the way?

A linkage adjustment issue? Yep, that's the first thing that popped
into my head when he said "not a serious bog, more like advancing the
throttle isn't making any difference".

Rick

JamesE wrote in news:1189164531.137067.326800@
19g2000hsx.googlegroups.com:

I must have checked the float level 10 times before I put it back
together. Of course I could be measuring it wrong however. On my
rebuild kit it had a note that said that with four cylinder engines
experiencing rough idle and flooding that it may be necessary to
change to a spring loaded needle. So I changed it from the original
solid needle to the spring needle and then readjusted the float
level. Could this be causing the problem? Also you mentioned that I
could have put in the power valve wrong. What could have gone wrong
with it? I just put the gasket on and screwed it in. Was there
something else I should have done? Thanks, James.


Silly me, but have we checked our fuel pumping capacity? It may simply
be running out of fuel! Fuel pump, fuel filters, clogged lines,
restrictions, clogged tank vent?

Open the tank's inlet at WOT and see if it doesn't speed up...clogged
vent.
Temporarily install an outboard motor primer bulb at the inlet of the
fuel pump for testing. Does it collapse when the throttle is opened?
(vacuum on fuel line). If you pump it by hand when the engine bogs, does
the engine perk up and have more power? (bad fuel pump). With the engine
off, if you pump the bulb, does it pump a few times, then get impossible
to pump (float valve closing off)...or does it continue to pump? (fuel
pump diaphram has a hole in it). Great little piece of test equipment,
primer bulbs. Too bad it's not "legal" to leave them in the line all the
time on inboards.

Let's test the fuel supply before we tear the carb all apart for the 22nd
time, ok?

Larry
--
Search youtube for "Depleted Uranium"
The ultimate dirty bomb......

Let's read the original post before we make a bunch of off suggestions, ok?

"Larry" wrote in message
...
JamesE wrote in news:1189164531.137067.326800@
19g2000hsx.googlegroups.com:

I must have checked the float level 10 times before I put it back
together. Of course I could be measuring it wrong however. On my
rebuild kit it had a note that said that with four cylinder engines
experiencing rough idle and flooding that it may be necessary to
change to a spring loaded needle. So I changed it from the original
solid needle to the spring needle and then readjusted the float
level. Could this be causing the problem? Also you mentioned that I
could have put in the power valve wrong. What could have gone wrong
with it? I just put the gasket on and screwed it in. Was there
something else I should have done? Thanks, James.


Silly me, but have we checked our fuel pumping capacity? It may simply
be running out of fuel! Fuel pump, fuel filters, clogged lines,
restrictions, clogged tank vent?

Open the tank's inlet at WOT and see if it doesn't speed up...clogged
vent.
Temporarily install an outboard motor primer bulb at the inlet of the
fuel pump for testing. Does it collapse when the throttle is opened?
(vacuum on fuel line). If you pump it by hand when the engine bogs, does
the engine perk up and have more power? (bad fuel pump). With the engine
off, if you pump the bulb, does it pump a few times, then get impossible
to pump (float valve closing off)...or does it continue to pump? (fuel
pump diaphram has a hole in it). Great little piece of test equipment,
primer bulbs. Too bad it's not "legal" to leave them in the line all the
time on inboards.

Let's test the fuel supply before we tear the carb all apart for the 22nd
time, ok?

Larry
--
Search youtube for "Depleted Uranium"
The ultimate dirty bomb......

Check the fuel filter and pump. Make sure it's actually getting the right
flow.