2000 90HP Johnson J90PLSSE Carb Problem

[Vin92]

With engine idling I pulled off one spark plug wire at a time and the lower starboard cylinder was the only one that didn't show a difference.
Swapped the plugs and wires and had the same results.
Swapped the lower carburetor assembly with the upper. The problem moved to the upper, followed to carb. Switched to port side and problem moved to port side. Completely rebuilt all 4 carbs (new floats, needle valves, gaskets, etc...).

Cleaned the "problem carb" 5 times. Check setup multiple times. All 4 carbs are setup the same exact way. Same issue. Running out of ideas.

......Any thoughts ????

 

[boobie]

Did you have the high speed jets out of the carbs ??

 

[Vin92]

The high speed jets are new, just replaced them on two of the four carbs when replaced the bowls (warped bowls).

 

[jakedaawg]

Is bowl vent clear?

 

[Vin92]

Not sure what the bowl vent is ?

 

[jakedaawg]

It is the passage that allows atmospheric pressure to reach the fuel in the bowl...its what makes a carburetor work.

 

[Vin92]

The air vent is totally clear and clean. It is not on the bowl on this carb. I believe it is called the intermediate orfice.

 

[jakedaawg]

Well something has been missed...are you sure your looking at the correct carb?

 

[Vin92]

UPDATE....
I ended up getting a carb from a blown engine from the local marine shop (I got lucky, free carb). Cleaned it up and transferred the jets from mine. Installed and started the engine. Problem solved!!!

I did clean mine again and I think the flow through the small tube (idle gas feed) may have increased. Hard to say, such a small difference. I will try it in the future.

Now I need to test it on the water with WOT. Hopefully I won't need to pump the bulb to get proper power

 

[jakedaawg]

Pumping the bulb is a fuel pump issue, not a carb issue. Check for air leaks in fuel supply. The cowl connector, both Male and female, dont last forever.

 

[Vin92]

Yes - I may have 2 issues. Last time when running on 3 cylinders I squeezed the bulb and the engine took off.
I will see tomorrow when back on the water.

Thanks

 

[jakedaawg]

Remember, no fuel = no oil, dont run with a lean issue or you risk your power head.it only takes a minnow...

 

[jakedaawg]

It.only takes a minute...darn auto spell

 

[Vin92]

Thanks !!!

 

[Vin92]

Took boat on the water. Idles nice but no top end power. Couldn't get on plane.

Float Height question ......
I setup my float height per the manual. Approx 1" from the gasket to the bottom of the float. This is not a 1" drop, much less. Does this sound correct ??
Some say a 1" drop and others say 1" from the gasket to the bottom of the float. Big difference.

Thanks.

Vin

 

[jakedaawg]

Has this boat and motor ever run well for you?

Time for a compression test before more dollars. Report results.

you will need to verify that the throttle plates are indeed opening all the way at full throttle.

you will need service manual for the link and synch. Need to verify timing and what not.

compression test is a must do first thing.

 

[Vin92]

Boat ran good last year. I have owned this boat for 8 years. Did compression test last month. All cylinders were between 105 and 115. I will look at throttle plates.