78 evinrude 70HP acceleration problems

[ing]

This motor was running great and the last two weeks it has developed accelleration problems. It idles fine but when you throttle up it starts to go and then just bogs down as if starving for fuel. Ive rebuilt the carbs. replaced the coils, plugs, plug wires, power pac, fuel pump and filter, as well as the fuel lines to the tank. All this over the last year. This problem is somewhat intermittent as there are times it works fine. I am at a loss as to where to go now as it ran so well just a couple weeks ago. thanks for your help

 

[ondarvr]

Is the timing plate moving correctly, have you checked for spark when it's acting up, tried squeezing the primer bulb or hitting the choke as it bogs?

 

[F_R]

Check for a sticky timer base plate. If it lags, it will bog out big time when you try to accelerate.

 

[ing]

I have tried squeezing the primer bulb with no effect. it runs smooth even when it bogs down but I will check the spark. havent checkthe choke while running but have while sittling and it functions fine. I Will try it while it is runing.
If the timer base is sticking how do I fix it of do I need to replace it?
Thanks for your help

 

[ondarvr]

If it's sticking you need to remove the flywheel then clean and lube it.

 

[mrcj001]

When you give it throttle and starts to bogg, try "blipping" the choke....if it takes off that indicates it a lean condition.

 

[ing]

I tried engaging the choke while bogging down and no change. The engine while not under load and hooked to the hose seems to run fine and will reve up in or out of gear just fine. I did find some debris in the pump filter screen and cleaned it out but that did not solve the problem.. Is it possible some of the crud passed the screen and clogged the carb jets? thanks again for your help

 

[mrcj001]

When you rebuilt the carbs did you remove the high and low speed jets and the core plug? Sometimes its not the debris you can see, its the build up of varnish that starts to constrict the small fuel passages. If the fuel pump is old you may want to replace it.
Check compression and make sure the engine is in good shape before spending money on replacement parts.

 

[mrcj001]

If you do recheck the carbs...make sure the needle valve hanger doesnt get caught up in the float hing. It very easy to do and causes problems like stuck open or shut floats.