1988 Johnson 70 hp spitting back out of top carb

[Grifftro000]

I have a 1988 70 hp johnson that's been spitting out the top carb. I've taken the top carb off and swapped it with the bottom carb and still got fuel spitting out of the top carb. I've taken the intake manifold off and checked the reed valves, and the top reed valve wasn't much different then the other valves. Any idea on how to tackle this?

 

[racerone]

Are you 100% sure that there is something wrong ?----How does the motor run ?

 

[flyingscott]

Sounds normal.

 

[Grifftro000]

The motor dies when i am trying to put it on the trailer. Only the top carb is spitting gas and its dropping rpms every time it spits gas. It's like the carb is coughing

 

[flyingscott]

Do a.compression test. I have had several of those motors and they all spit out of the top carb. How does the motor run when using normally? Is the cam roller in good condition?

 

[racerone]

The top and bottom carburetors are the same in the way they work.----So if the bottom carburetor spitted the same in the top position what does it mean ?

 

[flyingscott]

Does it spit.out of the throat or the low speed orifice?

 

[Grifftro000]

The compression was about 110 in all 3 cylinders, the bottom carburetor spit the exact same when it was put where the top carburetor goes. The carb is spitting where the main jet (I'm guessing that's the throat) is and comes out with a puff of smoke when it does. It spits with the throttle plates completely closed. The motor will idle on the ears just fine and won't die, but whenever it's just putting around in gear it dies and is very difficult to load on the trailer. Is the throttle cam the piece of metal that leans against the roller on the 2nd carb?

 

[racerone]

Up to you , but I would take the head off to have a look.----Head gaskets are cheap.

 

[Grifftro000]

Why do I need to take the head off? Is the compression not good enough?

 

[racerone]

I will bail out in trying to help.---Good luck with this motor.

 

[boobie]

Did you try any re-jetting in the upper carb ??

 

[Grifftro000]

Did you try any re-jetting in the upper carb ??

No, I don't think it's a carb problem as swapping them did the same thing, so I haven't tried to do anything to the carb

 

[flyingscott]

No the compression test is not good enough. Pull the head to look at the bores those can score on the exhaust side and cause problems like that.

 

[boobie]

Carbs could have the same jets in them so swapping them would make no difference.!!