Engine surges as approaching WOT???

[jsmendzi]

I have a 2004 40hp Johnson that I recently purchased. As I start to approach WOT the engine starts to surge, almost like it is not getting enough gas. I cleaned the cards today, and recently refitted them with a carb kit, have checked the fuel filter and fuel lines for blockages / leaks, checked the floats, and spent some time playing with the idle screws. When the engine is running the primer bulb is hard… I don’t think it’s b/c the engine is not getting enough gas (ie. fuel pump failure); when removing the fuel lines to the carbs the gas pours out. I have also tried spraying gas into the carbs when running to see if that helps. Does anyone else have any suggestions as to what it may be? I’m at a loss - I just don’t know what to try next?

 

[mark.aa]

Re: Engine surges as approaching WOT???

see (bogs down at WOT post.)

 

[Goodoleboy]

Re: Engine surges as approaching WOT???

Seloc manual says that surgeing at WOT is almost always caused by faulty fuel pump.<br /><br />Just because pump seams to be good at idel, Does not mean its still pumping correctely at WOT.<br /><br />Also a sticky needle valve in carb. can act the same way. A float that rubbs the side of bowl will give the same sympton,s.<br /><br />A air leak at the welch plug,s on carbs will cause power loss. The little lead shot seals can also vibrate lose and cause WOT problems.<br /><br />Good luck!

 

[jsmendzi]

Re: Engine surges as approaching WOT???

Thanks for your suggestions Goodoleboy. The motor doesn't only surge at WOT, it starts around mid throttle. I don't think it is a fuel problem b/c when I either spray extra fuel into the cards, of pull out the choke, it chokes the engine. I checked the floats yesterday and they definetly are not rubbing against the side of the bowl and I just fitted a carb kit on the carbs, and the needle appears to be working correclty. I will try checking again for air leak on the welch plugs, and let you know. Thanks again.

 

[jsmendzi]

Re: Engine surges as approaching WOT???

Fuel pump is only $40-$50, should I replace it, or could it be something else? I am replacing all fuel hoses today to see if that helps at all...