115 Johnson sputtering/cutting out under load??

[docgreen9]

Hi, new member hoping for some help with a problem. I've got a 7 year old 115hp Johnson saltwater edition motor. It's carb'd model and had never, ever had any problems till last week. While cruising out to fish between 4k & 5k rpm it started to sputter/cut out, it would buck and jerk and loose power. I could see the tach fluctuate. We got it back home and started working on it. Plugs were a year old, wires too. Checked all the grounds for corrosion, pulled the coils off and the lower one was cracked really bad on the bottom. We suspected these. Ordered new coils ( 2 ) replaced them this weekend. Also replaced the plugs just for giggles, changed the fuel filter on motor, replaced spin on filter in boat, wires are only a year old. Took it out Saturday and ran great all day. Coming in for lunch started doing the same thing again. I tried pumping the squeeze ball to see if it was running out of fuel and no change. It won't get on plane when it's doing this, due to lack of power, but then it'll clear up and run great for several minutes and do it again. So it's hit and miss. Any ideas? Fuel pump? Carb issue? Hope it's not the power pack $$$$.

Thanks for your help.

 

[iwombat]

Re: 115 Johnson sputtering/cutting out under load??

Sounds like you've got a fuel delivery problem. Did you check the screen in your fuel pump?

A hard bulb would tend to rule out a problem in the tank, but you might try a portable tank and hose if it happens again just to rule it out.

 

[Walker]

Re: 115 Johnson sputtering/cutting out under load??

Also make sure the coil grounds are clean.

 

[docgreen9]

Re: 115 Johnson sputtering/cutting out under load??

iwombat ... I didn't check the screen in the fuel pump. I replaced the filter/screen thing ( cone shaped ) where the fuel line connects to the motor. I also read about some screens in the tubes that go down the outside of the carbs. The fuel bulb never has been hard when pumped up.

Walker .... I did clean them the first time. I was hoping that was it but it didn't help. That's when I noticed the coils were split all up on the bottoms.


I'll have to take a better look and see how the fuel flow is. I read in the service manual about putting a pressure gauge inline after the pump. I might try that next too or as suggested run everything off another fuel source.

 

[iwombat]

Re: 115 Johnson sputtering/cutting out under load??

"The fuel bulb never has been hard when pumped up."


Well, there's the smoking gun right there, you've either got an air leak, a fuel pump rebuild is in order, or your carb float needles aren't closing.