76 70hp evinrude dies at half thorttle

[Josedcr]

With the water muffs the motor runs without issues. In the water, the motor idles well after start, gets into gear fine, when the throttle is pushed past the half way point, it dies. If I run the motor in gear at very low speeds for several minutes and then slam the throttle forward, it boggs down but then it kicks in and runs at full throttle smoothly. After I throttle down it idles high. I have tried pumping the fuel bulb while throttling up but it does not make a difference. It has no thermostat or flow restrictors on the head (left them out on head installation) and the water has been around 65 degrees. Could it be that the motor is too cold to run? I have not check the compression.

 

[Josedcr]

Re: 76 70hp evinrude dies at half thorttle

Hi everyone,

I need some help on this one. I just did a compression check and all 3 cylinders are around 123. I also did a spark test and the spark was bright and blue at a 7/16 gap. The carbs are clean.

 

[ebauman]

Re: 76 70hp evinrude dies at half thorttle

same year and problem as mine. needs carbs rebuilt. Also try putting new spark plug boots on all three coil wires,this helped mine greatly. As for the fast idle after throttling down, try tightening fast idle screw on front of control box. Eric

 

[patrick4266]

Re: 76 70hp evinrude dies at half thorttle

First off the thermostat is there for a reason. Buy you a new one. Sounds like you need to rebuild the carbs, not just clean them. Do that and a link and sync and you should be fine.

 

[mrcj001]

Re: 76 70hp evinrude dies at half thorttle

. After I throttle down it idles high. .

The link & sync is out if adjustment....if you are getting erratic idle after throttling down, the cable is out of adjustment.

Do this first:
Be absolutly sure the carbs are clean and the jets are clear. Be sure fuel system is fuctional. Install the proper T-Stat...the engine need to get to 145* or so to run right. Running to cool, its not burning all the fuel right.

Start the engine and let it warm up. disconnect the throttle cable at the engine. Re-start the engine and adjust the idle (with the cable off the lever) to around 900-1100 rpm. shut off the engine and re-connect the cable to the lever. You may need to turn the trunion nut on the throttle cable to get the connection to match up to the new position to the throttle lever.

In other words, adjust the cable to the throttle lever....not the lever to the cable.

 

[Josedcr]

Re: 76 70hp evinrude dies at half thorttle

Thanks everyone for the info. I took all carbs apart (completely). Cleaned every orifice/jets and applied a good amount of sea foam spary. I checked all the fuel hoses and replaced the fuel pump (at motor) with one I had and know it was operational. I'll be looking for a thermostat and checking the linkages for alignment. I bought this motor a few months ago and it has had the same issue since I got it. I notices that the prop is an aftermarket stainless prop. The motor will go to full throttle if i let it run for a couple of minutes at very low speeds and then push it fast to full forward. I first thought that the motor was warming up during that slow period, but I'm starting to think that the speed of the boat (although little) is helping the motor get over the hump. Could the prop be the wrong type (angle, etc.), and how can I tell?