1986 90 hp Evinrude dies at a low idle

[Leifawilkinson]

I have been working on a 1986 90 hp evinrude that I got not to long ago and it starts up great and runs like crazy when I first start it with the lever up by the ignition but as soon as I put the lever down to the run position it dies before I can even get it in gear. I just replaced the thermostats because I had it out and it over heated so it's running cool now but I'm not sure even where to start looking to adjust for this problem . Any suggestions would be greatly appreciated.

 

[interalian]

When was the last time the carbs were rebuilt? Could be clogged idle passages. Or it could just be needing to warm up a bit more while gradually lowering the fast idle lever, before dropping to low idle.

 

[Leifawilkinson]

I don't know if the carbs have ever been rebuilt. I let it run at fast idle for 10 min and it still died when I lowered the throttle. I think I'm letting warm up enough but I could be wrong.

 

[emdsapmgr]

If the idle rpm's are too low, it won't be able to sustain itself when idling. You need to try to set the idle first, then decide if the carbs need rebuilding. The idle rpm's need to be set by the following. 1. Dunk the boat in the lake to normal float level. 2. Start the engine. 3. Shift into forward gear. 4. set idle rpm's to between 650 and 750 rpm's. You can't set the idle when the boat is on the trailer in the back yard. Once the engine runs at idle speed-then note what the engine is doing. Runs ok? Has a "lean sneeze"?

 

[Leifawilkinson]

Ok thank you. I will try that out when I get my boat in the water this weekend. Thanks for the suggestion

 

[racerone]

Compression test needs to be done.

 

[Leifawilkinson]

so i finally got my boat out on the water still had trouble so i took it home and pulled off the fuel pump and sure enough the membrane inside the pump had a tear in it. it was one of those pumps that mixes the fuel and oil. put on a normal new pump and the thing works great. thanks for the info and the help.

 

[Fed]

You have to put oil in the fuel tank from now on.