Lack of power 140 hp Johnson

[bcamp2009]

I have a 1983 140 hp Johnson. It starts and idles fine. When I give it throttle it kind of boggs down and has no power and does not go very fast.

It ran awesome the last time I had it out.

I have checked the compression it is good. I checked the spark present at all 4 cylinders.

Not sure where to go from here any suggestions?
Thanks

 

[emdsapmgr]

Re: Lack of power 140 hp Johnson

I'd recheck for spark when the engine is bogging in gear under load. The ignition system is under most stress at that point and any weak component tends to fail. An inductive timing light is necessary. If spark is still strong you can divert your attention to the fuel system. A weak fuel pump can be overcome by constantly priming the fuel hose bulb. That will force extra fuel into the carb bowls, insuring it is getting enough fuel.

 

[kenmyfam]

Re: Lack of power 140 hp Johnson

Pumping the bulb is an easy and quick check and gives an instant answer.

 

[bcamp2009]

Re: Lack of power 140 hp Johnson

I double checked the spark with an induction timing light and all four wires are showing consistent spark.

Im thinking it might be in the fuel system. I noticed when i prime the bulb I can't seem to get the primer bulb to go hard it almost seems the fuel keeps coming back what would cause this I have tried 2 diferent gas lines and the same result?

 

[kenmyfam]

Re: Lack of power 140 hp Johnson

Will the spark jump a 1/2" gap on a spark tester ??
Is the bulb the correct direction on the fuel line ???
Did you check it when it was "bogging" as suggested ??
How is the fuel output from the pump to the carb's ???

 

[emdsapmgr]

Re: Lack of power 140 hp Johnson

Kenny is absolutely correct, you can connect the hose backward-check the arrow on the primer bulb for direction of fuel flow. The fuel primer hose bulbs have ball valves in them which control the pressure when you prime the bulb. Unlikely that both fuel hoses have a bad bulb. You might have a fuel leak somewhere under the cowling which will bleed off the pressure. You could remove the fuel hose end where it connects to the fuel pump and then repeatedly prime the hose bulb. If that procedure causes fuel to pulse out of that hose end, you are probably ok.

 

[bcamp2009]

Re: Lack of power 140 hp Johnson

Well finally had time to figure out the issue. It turned out the bottom Carburetor was completely clogged and the motor was running on top 2 cylinders only. Cleaned out carbs and she run's great again.
Thanks for the help and advice guy's.