Starts fine, runs good, then dies when returning to idle

It's a 1993 90hp Evinrude and like the title says, it starts fine and runs fine... but occasionally after running on plane for ~10 minutes, when coming off plane and taking it out of gear, it'll abruptly die. Starting back up isn't too much trouble but it wants a little gas to do so. I have the same problem on a '76 50hp Merc. Any indications of what this may be a sympton of? Fuel filter? Fuel pump? or?

Re: Starts fine, runs good, then dies when returning to idle

If the eng.runs good at high speed,I wouldnt think a filter would be the problem,thus the fuel to the eng.is ok.Do yu have a tach?If so,the eng should be running about 700 at idle,in gear,if its too low ,it may stall,you might raise the idle a bit,if its not an idle adjustment,look to see the timing base under the flywheel is operating ok,see that it slides from open to idle ok,if none of that helps,your carbs could be out of sync,but I dont think its that,did the eng lay up for a while not running,you could have some crud in the low speed jet(s) in that case,you may need to have a carb cleaning,which meand total disassembly of the carb,soak the parts incarb solution and blow throuh all passages with compressed air,or at least using a carb cleaner spray with the tube attacheedblow into all passages.Look the easy look over first,then try the idle speed increase

Re: Starts fine, runs good, then dies when returning to idle

same operator, two engines, same problem, see a pattern developing here..........sorry, just kiddin.....if you have a carburetor needle valve or two leaking, could be flooding when you back off the throttle - when was the last time new carb kits were installed?

Re: Starts fine, runs good, then dies when returning to idle

Thanks for the replys guys. The in gear idle speed actaully fluctuates... and perhaps that's the real problem here. Seems like it idles in gear high cold (~800 - 900) but once it's warm it becomes lower, ~650 and is a little shakey. The other thing I could mention is it seems common to coming off plane abruptly from 3000 rpm's to idle (tubing)... which is really when you don't want it to happen! General docking / operating & gradual slow down doesn't seem to kill it.

jtexas - same operator, 2 engines, same problem... I hear ya! I've been questioning myself on this as well :redface: New carb kits have never been installed (to my knowledge) on either engine. I hate to mess with the '76 Merc because I've owned it for 7 years and have had to do nothing but change lube and plugs... it's been unbelievably reliable for a 31 year old engine. The Rude is new to me this year.

Re: Starts fine, runs good, then dies when returning to idle

The motor idles high when cold because if it has a QuikStart powerpack which advances the timing until the engine reaches 96 degrees F. or 1100 RPM.

When the engine timing and the idle are set, the mechanic has to make allowance for that or the engine will stall when returning to idle speed after warm-up. It is a little bit complicated, but your service manual has detailed step-by-step instructions.

Re: Starts fine, runs good, then dies when returning to idle

My 1981 60 hp johnson will do this also i figure it is flooding out but cant figure it out. I rebuilt the carbs but due to something not right i have switched the needles and seats several times and no longer know which set is the new and the old i always replaced them togeather though.

Also mine almost always will only die if i abrubly stop or if i just shove the throttle to idle. If you decellerate slowly it never seems to be a problem except on a rare occasion.

Also several weeks ago i had another problem that i read another poster had is the engine flooding after stopping which someone said may be inlet needle also. I stopped after about 1/2 hour running from (wot to idle to 3/4 throttle) then say 3-5 hrs later when leaving the beached location the motor would not start then i chocked it and still would not start so i increased the idle and it started and ran rough untill it burned extra fuel off (big puff of blue smoke). Then ran flawless all the way back.

-just letting you know your problem is not unique as i have thought mine was. But i kept telling myself there are so many of these things that there is no way i have a problem that no one else has and i have proven myself correct.



-nate

Re: Starts fine, runs good, then dies when returning to idle

Thanks everyone again. Yeah Nate... "misery loves company" as the saying goes... although this isn't really "misery", just slightly annoying. The slow deacceleration is the key. However, I've got a 4-5 year old daughter that has fallen in love with tubing and I want to keep it that way! Getting stopped quickly and pulling her back in quickly is critical to her continued happiness with watersports... which really equates to more boating time for dad! Already enjoying fishing and water skiing starts this summer!