Runs when at fast idle but dies under load

[emtolandon]

I have a 1977 70 hp Evinrude. It will start when I have the choke up... I let it run for a few and lower the fast idle to idle. Most of the time it just dies out. Sometimes it will idle and let me give it power. When I give it power one of two things happen... it either dies or it will go... so I give it more and it runs great for about 20 seconds then it dies out... and it takes a second or two to restart. As long as I have the fast idle on it runs and runs and runs. Any ideas?

 

[jonesg]

Re: Runs when choked and only short time when not choked

Re: Runs when choked and only short time when not choked

When did you rebuild the carbs?

///bump

 

[emtolandon]

Re: Runs when choked and only short time when not choked

Re: Runs when choked and only short time when not choked

not sure when they were rebuilt. I just got this motor. I should have said fast idle instead of choke.

 

[steelespike]

Re: Runs when choked and only short time when not choked

Re: Runs when choked and only short time when not choked

Sounds like the carb(s) needs a rebuild.Idle circuit appears to be gunked up.

 

[rsimmons42]

Re: Runs when at fast idle but dies under load

i have the same engine and when I first got mine it was the same deal, carbs were in need of rebuilding, after that check you link and sink and you have a good chance of the problem being fixed, have you checked compression?

 

[tashasdaddy]

Re: Runs when at fast idle but dies under load

start at the beginning, and check yours spark on all 3 cylinders, and compression. spark should jump 1/2 inch, compression should be over 100 psi, and with in 10% of each other. if these are good, then go to the carbs. read this. http://forums.iboats.com/showthread.php?t=244013

carb kits iboats store. http://www.iboats.com/mall/partfind...gd_poid=109332&gd_row=54&**********=086765719

 

[jonesg]

Re: Runs when at fast idle but dies under load

With an unknown quantity , may as well do the whole thing ...
get a water pump kit too,
drain and change lower gear oil, order new seals for the drain/fill screws. Change the fuel filter,
remove prop and check for fishing line on the prop shaft.
Make a shopping list and include a factory manual,
not the aftermkt manuals, you'll save hundreds.
Any of these little projects can ruin your engine if theres a problem and left unserviced.
As Tash said, check compression and inspect the plugs, it will tell you a lot in 5 minutes. Then you'll know everything is as it should be.