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When you say it looks like the lower carb is not atomizing the fuel, can you be more specific? What are you seeing that makes you think that?
Also, how did they look when you took them apart? Were they fairly lean on the inside, or in rough shape?
Have you done compression and spark output testing on the engine yet?
What kind of compression numbers did you get?
Also, on the spark test, there is a right way and a wrong way to do that. What kind of tool did you use to check spark output?
Got it. The next thing is have you run the engine off of another fuel source, a different tank? A well as trying pumping the primer bulb over and over and over?
If you run the engine and hold your palm flat against the bottom carb, do you feel suction or can you feel any spitting back at you?
On your engine are the fuel pumps part of the carbs or is it a separate pump? They make them both ways.
The pump has 3 lines on it. Fuel in, fuel out, and pulser. The pulser line runs between the pump and block. Is this the line you are seeing fuel in?
Do you have a fuel pressure gauge that you can hook up in order to measure fuel pressure while underway?
The only thing that is going cause fuel not to atomize is bad reeds or a clogged carb. we covered the reeds, if it had bad reeds you would feel it spitting back out at you. You said you rebuilt the carbs, I can only take you at your word that you know what you are doing and did the carbs correctly.
Have you ever seen this engine on the boat it sits on now make full power?
We can test if the carb is flowing or not if you have a good sized compressor. Do you have a good sized air compressor along with a decent blowgun?
If the engine has the wrong prop on it, it might simply be overloaded. What size and style boat is he engine on now? Between yourself and all the gear, how much weight are you putting on the boat? And what size prop is on there now?
Sounds good, let me know what you get for a prop size and then I will run all the numbers. .
The only test on the reed valve is hold your palm over the carb and see if you feel pressure. You should never feel pressure, only suction. And if you feel suction, then the engine would be drawing fuel in from the carb unless the carb is clogged. To see if the carb is still clogged. Take the carb back of, make sure it has fuel n the float bowl. Hold the carb in your hand and open the throttle all the way. And then hold the blowgun about 2 to 4 inches away from the throat of the carb and blow right through it. If the carb is flowing properly, you should see a fine atomized mist of fuel exit the other side of the carb. If the carb is clogged, you won't see anything. Does that make sense?
With the engine running.
Reving the engine in neutral does not mean anything, all its doing there is spinning it's own weight, not making horsepower.
I thought we established the fuel pump was a separate unit. Let me get the engines serial number that way I can run it and see exactly what you got there. These engines were made for 20 years and they came configured a dozen different ways.
Got it. There are no fuel pumps inside of the carbs. Pull the bottom carb and do the test with the blowgun and see if it shoots atomized fuel out of the back of it or not. That will tell you if the problem is still in the carb or someplace else.
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When you look into the bottom carb, do you see the black plastic nozzle?
yes is it there
When you saw the fuel pattern in the carb, what RPM was the engine at?
Did you use a timing light or just a flash light to look into the carb?
The fuel droplets that you have seen is what I was referring to.
I dont think that you are running on all 4. The bottom must not be able to burn that mixture going into it. Take the bottom carb back off and really inspect the area around where the tube come into the carb body. There may be a crack there, or the tube is not installed tightly.
Sort of, it is the brass tube that screws into the venturi.