evinrude 70 hp 78 throttle up dies.....

Folks I need help on further trouble shoot ideas...at the end of my rope. Motor sat for two years before I bought it (cheap)<br />Motor had good compression (will recheck this week),starts smoothly, has carbs rebuilt, new fuel pump, getting gas from tank, idles okay, but dogs on throttle up...<br /><br />Question: could this be an electrical problem ...power pack etc? It appears to get good spark on the cylinders...I have the manual but this is a weak spot in my understanding...can it still be a problem on throttle up???

Re: evinrude 70 hp 78 throttle up dies.....

Did you rebuild the carbs or have someone else do the rebuild? I had the same problem on my 70 Johnson. High and low speed orifices were gummed up. Air pressure and cleaner finally cleaned them out. Ran fine after that. Also, may be overpropped. What size and pitch prop and what size boat are you running it on?

Re: evinrude 70 hp 78 throttle up dies.....

slick, thanks for the reply....<br />I did the rebuild...twice perhaps not thorough enough but did take it all the way to the jets....<br />Prop is 17 pitch per recommend for boat and engine....<br />Have had her up before and planes well....<br /><br />If choked down I can coax her through....<br />wondering also if floats not set right may be the ticket....

Re: evinrude 70 hp 78 throttle up dies.....

DC,<br /> Here are the first things I would check in order:<br /><br />1 - Take air cover off so you can get a good look at the carbs and fuel lines, squeeze bulb till very hard and look for fuel leaks at all connection points, carbs and fuel pump. If all is dry then......<br /><br />2 - Start motor in the dark and look at the back side for any sparks jumping to the block from plugs, wires, coils etc. If nothing then....<br /><br />3 - I would suspect your high speed jets not to be as clean as they need to be. Did you pull them out and clean them or did you just spray cleaner through the holes? You can access them through the bolt on the lower front of the carbs without having to dismantle again.<br /><br />Hope one of these helps, let us know.

Re: evinrude 70 hp 78 throttle up dies.....

thanks for the reply, appreciate the site as my mech. skills are rusty and have gaps....yeah I sprayed them....will yank them. I bought a comp. gauge to double check....<br /><br />Engine is really acting gas starved ....changed tanks...have one more hose I will replace...<br />spark is okay.... bulb is new and hard. It does almost strike me as sucking air somewhere before carb or in float area.<br />Know just enough to be stumped. up date later. <br />Again Thanks.

Re: evinrude 70 hp 78 throttle up dies.....

GT150 is on the money with his suggestions. When I rebuilt my carbs the first time I only sprayed them down with cleaner, didn't do the job. Second time I used compressed air with cleaner, still didn't clean them all the way. Ended up running .032 wire through the orifices to clean them all the way. Those things will bugger up really bad if left sitting for a while. Hope you get it running good. Those little 3 cylinder 70s are almost bullet proof. I sold mine last month and miss it already.