94 Johnson 112 SPL Power Loss

[rogerdckwrth]

Hi, 1994 112 SPL on an 1984 18.5' Hewes Bonefisher

I have a peculiar problem. Engine starts ok at dock, I idle 1/4 mile to open water, I accelerate to plane at less than full throttle, after 1/4 mile or so engine looses power but does not stall. I return throttle to idle and then accelerate again and usually have no problem thereafter. I have rebuilt the carbs, replaced the fuel line and filter. I read another thread where a guy with the same engine found the problem to be the anti-siphon valve--where is this valve? Any other ideas?

What does SPL mean?

 

[tashasdaddy]

Re: 94 Johnson 112 SPL Power Loss

the special means it, is basically a 115 with out the accessories, vro, trim & tilt. but now most come with TNT, a stripped 115. you mix you oil and gas.

anti siphon valve is usually at the outlet of the built in tank.

 

[rogerdckwrth]

Re: 94 Johnson 112 SPL Power Loss

Thanks--I have replaced the gas line from the tank to the filter and I have no valve in the system--any other ideas?

 

[tashasdaddy]

Re: 94 Johnson 112 SPL Power Loss

when it starts to slow have someone pump the primer bulb, and see if it will pick back up. this would indicate one of 2 things, weak fuel pump, or you may need an anti siphon valve. could be that fuel is siphoning back to the tank, leaving an air pocket in the fuel line. when you prime you are bring gas, but there is still air in the line. 2nd is an educated guess.

 

[Silvertip]

Re: 94 Johnson 112 SPL Power Loss

The anti-siphon valve is the nipple the fuel line is connected to at the tank. It should simply unscrew from the tank. It has a check ball inside that prevents fuel from siphoning out of the tank -- and no, it's purpose is not to prevent backflow from the carbs. I doubt that's the problem anyway since the engine runs ok after the throttle up down process is completed. I'm guessing there is either a throttle linkage, cable, or control box problem, or sticky advance mechanism.