55hp 78 Evinrude wont idle

[nc4z]

Runs ok at high speed<br />At idle speed it will idle for a short period, start slowing down and then stop<br />Restarting is hard. Throttle trim must be wide open and engine must be choked.<br />Low speed jets, holes ,chambers, are clear in carbs. I can run a small wire into them all with no trouble.<br />I wondering about the screw in face of carb which screws into the low speed chamber. Can this affect the fuel flow. Should this screw be turned all the way in?<br />Thanks

 

[fireman57]

Re: 55hp 78 Evinrude wont idle

Turn the screw all the way in and seat it very very gently. Back it out about one and quarter turns. start your engine and let it warm up to operating temperature then turn it one eight of a turn out and let engine run for a full 30 seconds for the new adjustment to take effect. Keep turning 1/8 turn until it starts to cut out then go back an 1/8th at a time until you find your best idle. If you have a tach you can set your idle by it. Someone will correct me but I believe it should be somewhere in the realm of 600 to 800 rpm.

 

[nc4z]

Re: 55hp 78 Evinrude wont idle

Thanks. Ill try it. It idles ok in yard but not in water.<br />Ive about come to conclusion its the fuel pump or low compression.<br />Fuel pump diaphragm is wavy looking , not tight. I dont know how its supposed to look when new. I think Ill take someone with me to squeeze the bulb constantly and see if it will idle then. If so I imagine its insufficient fuel.

 

[steviecops]

Re: 55hp 78 Evinrude wont idle

I have a 1980 55. They don't idle great at the best of times, but there are a few things I did to improve mine.<br /><br />Take the carbs off, clean thoroughly with carb cleaner or engine tuner, then blow out the jets and passages with compressed air. The rebuild with new OMC carb kits. Do a link and synch and be as accurate as possible.<br /><br />Replace all the fuel lines and clips to make sure you aren't sucking air anywhere.<br /><br />Change the thermostat to make sure that your engine is running at the right temp. If it's too cool, it won't idle properly.<br /><br />Check all earth/ground connections to make sure they are clean. Change plugs to champions and gap them at .040.<br /><br />Then do a decarb. I did mine with OMC engine tuner.<br /><br />My engine did idle 100% beter after I did those things, but even now, it'll idle all day but it doesn't like it! It shudders and shakes if you leave it idling too long.<br /><br />Good luck<br />Steve

 

[fireman57]

Re: 55hp 78 Evinrude wont idle

If your fuel pump diaphram is wavy looking then rebuild the fuel pump along with the carb.

 

[Joe Reeves]

Re: 55hp 78 Evinrude wont idle

The 1978 55hp Evinrude DOES NOT have adjustable jets. The jets are all brass fixed jets. The screw you speak of has a red fiber washer in back of it, and that screw is a plug which prevents air from entering the fuel passageway. The screw must absolutely be screwed in tight.<br /><br />The problem you speak of, assuming that the engine does idle properly for a short time, would be caused by either fouled carburetors, flooding carburetors, or a lack of fuel being supplied to the carburetors.

 

[fireman57]

Re: 55hp 78 Evinrude wont idle

Thanks for the correction Joe.

 

[nc4z]

Re: 55hp 78 Evinrude wont idle

Installed fule pump kit and finally was able to test today. Working ok now.