Rebuilt carb and now will not run at cruising rpm

[lost in translation]

Hello,

I’ve worked with a friend to rebuild my carburetor after the float sometimes stuck and it got so that it would only run with partial choke.

My friend installed the Moyer rebuild kit and now the motor starts and idles well but will not go over 1200 or so rpm. Any more throttle than that and the engine struggles and will die.

What did we do wrong? Any suggestions?

Thanks in advance.

[Dave Neptune]

Are you sure the float level was set to spec and still parallel to the housing?

What you state regarding the choke indicates either lack of fuel to the main jet assembly. Is the fuel pressure good and are the filters fresh?

What RPM did you get before?

Dave Neptune

[lost in translation]

Thank you, Dave. I am not sure on the float valve settings. Do you know what the spec should be for it and how to set it up?

The motor now starts and runs without choke up to that high idle, 1200 rpm or so. The partial choke was required before we did the rebuild.

[lost in translation]

I used to get to 2000 rpm or so in gear.

[roadnsky]

Thank you, Dave. I am not sure on the float valve settings. Do you know what the spec should be for it and how to set it up?

Here is a thread on the subject.
Another here.

And here is a quote on the procedure from Dave himself a while back...

"When adjusting the float, err to the high side of the setting, which is a lower fuel level.

Hold the top half of the carb upside down with no gasket and the float installed, check the height with a scale (good ruler). The factory setting is 1 5/32" to the bottom of the float, which is on top and resting against the needle which is resting on the seat.
Two things of import here...
1-Be sure the bottom of the float is parallel with the body (this controls the closing position of the float accurately) of the carb, or as close as possible.
2-When tweaking the tabs use a pair of needle nose or duckbill pliers.
DO NOT PUSH, PULL OR BEND the tabs by holding the float itself. Only hold the brass tabs.
Now you can bend the larger portion that attaches to the float for the parallel adjustment and the little tab that rests on the seat for the height.
This can be a bit frustrating so go slow and easy. I suggest that if anything, you set the float a bit HIGH @ 1 3/16~1 5/32.
These adjustments are important to control the emulsion wells that mix air into the fuel to break it up! The factory adjustment specs are 1 5/32 +/_ 1/32" which is why you need it to be as parallel as possible. I run mine at 1 7/32 and like the way it performs."


You might also want to invest in the $12 instructional video on the carb by Don

[Dave Neptune]

What kind of fuel pump are you using?

It seems that the performance of the carb did not change after the work. Does it still run better with the choke, IE more RPM's?

I would confirm fuel delivery at the carb with a pressure gage. Often you can have fuel flow out of the fuel line but not have enough pressure to actually feed the carb under load. This may be an easier check than another disassembly of the carb. If you have 2~4 PSI at the carb then I would consider looking at the carb again.

Did this problem sneak up or start all of a sudden?

Dave Neptune

[lost in translation]

Thank you both. I purchased Don's video which is excellent.

The problem encountered now with an inability to throttle up beyond 1200 or so is new and occurred immediately upon fitting the serviced carburetor. The reason why I wanted to do the carb service was two fold:
1) I had had the float valve stick on rare occasion.
2) The engine just started to need the choke pulled out a bit to run well.

Now the engine starts and runs well (but only up to 1200 rpm) without the choke. If I pull the choke out, it begins to stall the engine. If I throttle up beyond 1200, it begins to stall as well.

I have an electric fuel pump and can hear the clicking of it when the engine is not running. I do not have a pressure gauge and perhaps should buy one.

Watching the video from Don, I can share something else that may be important. We could not remove the float valve seat (the brass fitting here:

The slot for a screw driver to remove it got a bit mangled and I am wondering if that is what is causing the issue and also how best to remove this damaged part since it will not turn for us.

[ndutton]

Two tests in one

When you throttle up and the engine starts to stall beyond 1200RPM, does adding choke right then improve or degrade the stalling symptom?

[Dave Neptune]

RE the seat. If the buggering is not interfering with the needle IE no chunks interfere and are outside the finished diameter of the needle's hole there should be no issue. It takes something to catch the needle to cause problems with sticking. However the actual seat at the bottom of the hole where the needle end seats must look pristine NO NICKS.

Often the fitting can be removed with a small pair of mini channel locks, craftsman has a good one. Be careful not to mess any of the base of the carb where the seat screws in for a SEAL. If the actual seat for the point of the needle is good you may be better off just leaving it.

You can clear some of the destroyed part if it is interfering but the actual seat must be pristine. The seat can be dressed with lapping compound and a sharp dowel.

Dave Neptune

[roadnsky]

Here are a few pics to help the discussion and illustrate a little of what Dave is explaining...

[lost in translation]

The advice on this forum is so good. Thank you and thank you to Don for his video on typical carburetor issues. Well worth buying. Should have bought it earlier.

We found a missing piece in the reassembly and were also able to remove and replace the float valve bushing I spoke of earlier. I took a large drill bit for wood and made it a large slotted screwdriver by using a dremel too. Using a vice and impact mode on the drill made it easy to remove the old bushing.

The motor runs better than ever now. Feels good to be able to get enough power to make some good stern waves on the C&C 36 again.

[Dave Neptune]

What was the missing piece?

Dave Neptune