135 hp 1974 Evinrude few seconds of power then bogs down

[lpesca]

I have a 1974 Evinrude 135hp. If I start and let idle and then put in gear and put throttle down to plane it will take off normally for a few seconds and then bog down. I can also run at intermediate speed and cover the choke plates and it will speed up for a while. The upper carb seems to function properly. I did take the carb apart and clean up and blow out jets which seemed to be clean for the most part. This procedure did help with idleing as it wasn't firing on one of the barrels before this was done. I can repeat the procedure of idleing and then taking off well for a few seconds. My thoughts are that the fuel chamber is running out of gas. Float is empty when shaken. Will needle getting hung up or float adjustment cause this problem - (fuel pump doesn't seem to fit here) Thanks for your help

 

[lpesca]

Re: 135 hp 1974 Evinrude few seconds of power then bogs down

I have a 1974 Evinrude 135hp. If I start and let idle and then put in gear and put throttle down to plane it will take off normally for a few seconds and then bog down. I can also run at intermediate speed and cover the choke plates and it will speed up for a while. The upper carb seems to function properly. I did take the carb apart and clean up and blow out jets which seemed to be clean for the most part. This procedure did help with idleing as it wasn't firing on one of the barrels before this was done. I can repeat the procedure of idleing and then taking off well for a few seconds. My thoughts are that the fuel chamber is running out of gas. Float is empty when shaken. Will needle getting hung up or float adjustment cause this problem - (fuel pump doesn't seem to fit here) Thanks for your help

no ideas on this?

 

[emdsapmgr]

Re: 135 hp 1974 Evinrude few seconds of power then bogs down

You may have a weak fuel pump. When you hit the throttle for WOT operation, have someone constantly prime the fuel hose bulb. This will force extra fuel around the pump, directly into the carb bowls. If the engine picks up and runs normally while you constantly prime the fuel hose bulb-likely the pump is weak.

 

[lpesca]

Re: 135 hp 1974 Evinrude few seconds of power then bogs down

Seems that lower carb (both barrels) are ones causing problem as I can squirt quick start while running and it will pick up when lower carb is hit but not upper - can fuel pump be dominate on one carb more than the other
thanks for you reply

 

[emdsapmgr]

Re: 135 hp 1974 Evinrude few seconds of power then bogs down

You did a nice test with the lower carb. Next time use a spray bottle filled with premix fuel for that test. Your quick start has no oil in it to lube the engine. One other test: prime the fuel hose bulb. Then open the bowl drain screw on the bottom carb and see if fuel runs out. It should. Sounds like you need to pull the lower carb off and check the float and needle and set. Not sure if that carb had original cork floats or the newer plastic ones. Some of the old cork ones loose their varnish and won't actually float normally in gas like they did when new.. Did you pull the jets out and visually inspect them when you overhauled the carbs?