Motor Dies in Gear

[dblanton]

Hey everyone,
My 1981 75hp Evinrude dies when I put it in gear. I have rebuilt all three carbs, set the timing, synchronized, all by the manual, but when I set the idle to the recommended 700-750 rpm in gear in the water and unrestricted the motor will die. WOT is great top out at 5000 rpm, good acceleration, planes out good, no hesitation or bogging down when I full throttle out of the hole. Compression is 120 on all three cylinders. If I set the idle to 900 rpm in gear it will not die.
I am using the console mounted tachometer to set the idle rpm. How accurate is this type of tachometer, are there any variances in there readings.

 

[Joe Reeves]

Re: Motor Dies in Gear

On a flushette (hose) with the water on full blast, set the idle to:

1000 rpm if a 20" shaft engine.

1200 rpm is a 25" shaft engine.

The idle will drop to normal in the water due to back pressure.

Now, if that engine still dies when set as above, either the spark (ignition) is flawed, the carburetors are fouled, or the linkages are incorrect.

At what you consider a idle, in neutral, remove one spark plug lead at a time and note the drop in response. It should be exactly the same on all cylinders.

Let us know what you find.

 

[dblanton]

Re: Motor Dies in Gear

Thanks Joe for your responce,
I am assuming when you say "At what you consider a idle, in neutral" you are talking about having the motor in the water , not on the flushette (hose) when removing one plug wire at a time.
Should there be a difference from one cylinders to the other etc. what should I be looking at to correct the problem, Power Pack?

 

[tashasdaddy]

Re: Motor Dies in Gear

what joe is saying is when you pull the plug wire. that cylinder is not going to fire. note the sound and difference in rpms, when you replace the wire the rpms will pick back up. if the clyinder is not firing there will be no drop in the sound or rpms. and when replace the rpms will not change. that's the culpret. but still go thru all cylinders. then you need to isolate what is causing it. power pack, coil, pulg wire, plug, bad ground, low compression.

 

[dblanton]

Re: Motor Dies in Gear

Thanks , I will test this today.
Thanks again for your help.

 

[dblanton]

Re: Motor Dies in Gear

Ok,
I rechecked the compression on all three cylinders, all three are 120, rechecked the sync everything is synchronized according to the manual, all three carbs were rebuilt. With the motor running on the ear muffs I pulled each spark plug wire individually and watched the drop in rpm on the tach, the drop in rpm was the same on all three cylinders, but the motor will die if the idle rpm is set to the recommended 700-750 in gear, in the water and unrestricted, I still have to set the idle rpm to 950 to keep it from dieing in gear.
Can anyone help?

 

[tashasdaddy]

Re: Motor Dies in Gear

that may be the best we can do. as long as it shifts ok, make the shifts very direct, and intentional. don't try to slip it into gear, and listen to the cogs intermesh. damages the gears and clutch dog.