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1973 Evinrude 50hp Lark stalls when going into reverse.

C

Cvgkid

New member
I am new to the Forum and would really appreciate some help with this old outboard. I am trying to help my Son create an inexpensive fishing boat.
The motor runs well at fast or full throttle, but always stalls when going into reverse. It seems that an increase in idle speed might be useful, but not
sure if that is totally correct or how to properly do that.

Thank you.
CVGKID
 
Spark plugs should be Champion QL77JC4 plugs gaped at either .030 (long life) or .040 (super strong spark).

The 1973 50hp Evinrude model normally has a shaft length of 20" (Measuring from the underside of the transom bracket to the anti cavitation plate just above the propeller).

As such, running on a flushette, the idle should be set at 1000 rpm. When in the water, the idle rpm will drop to normal.

As Bobbie suggests... first thing to do is remove the spark plugs and run a compression check... then with the spark plugs still out, do a spark test.

What are the psi compression readings of the individual cylinders (top cyl is #1). Do not reply with generalities such as the compression is great... or good etc. Be specific.

The spark should jump a air gap of 7/16" with a strong blue lightning like flame... a real SNAP! Does it? Again, be specific.
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(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:

..........X1..........X2

.................X..(grd)

..........X3..........X4

This can obviously be modified to a 6 or 8 cylinder setup tester.
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Thank you so much for your suggestions. The top cylinder is just over 120lbs. Bottom cylinder is just over 135lbs. We will try the other things and reply.
Thanks again.
 
Simple stuff first. It may not be broken. Try setting the idle speed up a tad. And make sure the throttle cable is properly adjusted at the motor. Always adjust the cable to fit the motor, never adjust the motor to fit the cable.
 
Okay thanks, Racer.
May not pertain to this particular issue of stalling, but maybe idle is too lean? Does it restart easily after the stall? A motor running too lean at idle, may stumble/stall when shifted.
 
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