94 Johnson 112 SPL Power Loss

[rogerdckwrth]

Motor ran great all Summer (40 knots at 5500 rpm). The other day the boat started fine but would not come up on plane. After a few times it popped right up but then engine would intermittently loose and then regain power. Rebuilt carbs and fuel pump, checked fuel lines, and replaced plugs. Problem still exists except is worse--will not show any signs of normal power but starts and idles fine. Checked compression and got 105, 100, 102, and 89. I thought that I might have a bad cylinder but that does not explain why I would occasionally have full power--does it?

 

[tashasdaddy]

Re: 94 Johnson 112 SPL Power Loss

is the vent open on fuel tank, have you tried to pump fuel line bulb, when it starts to loose power? have you check spark on all 4 cylinders, should jump 7/16 inch? have you pull individual plug wires to see if there is any difference in idle? have you clean or changed fuel filter?

sounds like it is either not getting fuel, or you have a spark problem. did you fully disassemble the carbs, removing and cleaning the jets, and reassembling with rebuild kits?

 

[rogerdckwrth]

Re: 94 Johnson 112 SPL Power Loss

replaced fuel filter, vent ok, rebuilt fuel pump, rebuilt carbs (all needed) and replace one suspect coil. Not boat will start and idle fine but has not power to get on plane. Spark looks good with a spark plug tester but have not tried the 7/16" test. I have pumped the fuel bulb when the engine was running poorly with no change so I am pretty sure that it is not a fuel problem. Are there any tests for the power pack? Trigger? Stattor?

 

[jonesg]

Re: 94 Johnson 112 SPL Power Loss

the 7/16th spark test will tell you a lot about the ignition system.
My power was bad and it showed on the spark test.