WOT sputter/popping...low RPM

[Tinlizzy]

Re: WOT sputter/popping...low RPM

Yes laddies I just used carb cleaner and compressed air to blow out the high speed jets. They looked clean though.

What ignition parts should I check? I am still with you and leaning towards running lean. I am getting ready to dump this thing over board. Why would it run fine up until the economizer collar engages and fully opens the throttle plates? Thats when I hear the sputtering/popping and loss of RPM. The distributor stops advancing before the economizer collar starts to turn.

Would idle mixture adjustments effect the WOT at all by chance?

 

[Laddies]

Re: WOT sputter/popping...low RPM

The reason it runs fine till the secondary pickup (Economizer) starts to open the butterflies is its running on the low speed circuit till then and we both think that the problem is lean high speeds

 

[Tinlizzy]

Re: WOT sputter/popping...low RPM

Ahhh, thanks for clearing that up laddies now it makes A LOT more sense. I never knew when it started to use the high speed circuit.

Should I pull the carbs again maybe? And rebuild them again. I did not pull out the welch plug when I rebuilt them the last time.

Any other methods for checking the high speed fuel flow?

 

[Chris1956]

Re: WOT sputter/popping...low RPM

Tin, Make sure the main jet and the main nozzle are clean. The main nozzle has many holes, which can get clogged. I never had to remove the welch plugs, but I did remove the brass screw in plugs, which provided access to the jets and passages.

I also smeared some auto silicone over the welch plugs and brass plugs to assure they were sealed.

 

[Tinlizzy]

Re: WOT sputter/popping...low RPM

Thanks for the reply Chris, I guess I will keep digging.

 

[Willyclay]

Re: WOT sputter/popping...low RPM

Before you start rebuilding carbs again or cleaning out high speed jets, you can try an in-water test that should verify that the high speed jets are blocked or partially clogged. Let the motor warm-up before you trying advancing the throttle. Then try a run at WOT and when it starts popping and bogging down, activate your choke/primer. If the motor catches and starts to run what sounds normally at the higher RPM range, then you know for a fact it is clogged high speed jets. I just went through this same problem with a 2004 Mercury 60hp three cylinder. Fortunately, we could clean the jets without removing the carbs. I used spray carb cleaner and a needle to clean them. WARNING: wear eye protection when you spray the cleaner in the jets because it will come out of the carb mouth. Good luck!