WOT bogging down

[TC777]

Decarbed Friday. Saturday went to the lake. Performed great. Had a little bog when heading to the dock to load up. I thought it was running out of gas. Today went to the lake and when I opened it up, it would not even plane out. Did this for 20-30 min. Changed plugs, still same thing... Cleaned fuel filter out. Same thing. It cranks right up first try every time. Does not stall. After about 20-30 min it cleared up and ran good for about an hour and a half (28mph). Turned it off took a swim. Then it fired right up, got on plane quick, then started to bog down again. During this bogging it would get short burst of power, then right back to bogging again. It did this all the way back to the boat ramp. I would put it in neutral, then open it up, it would get power for the first few seconds then bog down again? Any suggestions? It is a 1975 70hp Johnson.

 

[BonairII]

Re: WOT bogging down

Carbs been cleaned lately?

 

[TC777]

Re: WOT bogging down

I was thinking it was probably the carbs. I was surprised that it performed so well the first time out. I haven't cleaned the carbs yet. Bought it 2 weeks ago, after it has been setting a few years.

 

[Solittle]

Re: WOT bogging down

Could also be air getting into the fuel line. When it starts fussin & boggin squeeze the primer bulb. If it smooths out start looking for an air leak.

 

[mherndon]

Re: WOT bogging down

Mine IS doing the exact same thing! I switched gas tanks with a buddy so those lines are good, but the lines in the motor may still have a leak. But either way, when I squeeze my bulb... nothing. I have replaced plugs, cleaned carbs, Seafoamed it... all to no avail.

So please, keep us posted! I am ready to break mine in half!

 

[TC777]

Re: WOT bogging down

It is leaking fuel somewhere. I can't figure it out. Took the air silencer off, took the air silencer base off, so I could get a good look at the fuel lines connecting the carbs together. The lines are clean, no fuel/oil on them anywhere. Looked at the lines to and from the fuel pump, clean. But, there is fuel/oil all underneath the air silencer. I am also getting fuel/oil in the air silencer, and at the bottom it had two nasty looking clots of oil/fuel. I did notice that the bottom carb had fuel/oil around the bowl gasket. Another question, can I clean the carbs without having to unhook them and rebuilding?

 

[Daviet]

Re: WOT bogging down

To clean the carbs properly you will have to take them off and disassemble them.

 

[mherndon]

Re: WOT bogging down

I am pretty sure our motors are similar and if they are, then yes. You need to take the carbs off to clean them. I can't take my bowl off without taking them off. Wipe everything down real good and make sure that your carbs our connected properly and when everything is together, prime the bulb and keep your head close to the motor. Listen and look for leaking gas and air coming thru the lines as you prime.

 

[TC777]

Re: WOT bogging down

Cleaned carbs. Changed all fuel lines to alcohol resistant. Took it out and it runs great. Gained 5mph.