1972 50HP Evinrude wont start

Hello iboats, im having trouble with my newly bought Evinrude engine, and i figures this would be the ideal place to get help.

So i have bought an 1972 Evinrude 50 HP, 50272C Electrical gear switch and throttle control.

I had been sailing for 1 hour or so, sailing with the engine on all different speeds min speed to full speed, and it ran and started flawlessly. Then after a good bit of sailing i was on my way into the harbor again, i was sailing slow as i was almost in there, when it suddenly started stuggling with keeping up i could feel the engine power going down and up for a little when it then turned off. I then couldnt turn it on again, when i turned the key its just made the cracking sound and nothing happended, also sometimes the starter didnt go enough up to attack to the main cranck gear and it would just spin like crazy. So i waited 15-20 min and when i tried there, it started. So i sailed slowly into the harbour thinking that it was just a random little issue and that its fine again, but 2-3 min after sailing in the harbour in stopped again, and this time for good, i havent gotten it started since.

When i try to start it, the starter goes into the cranck gear and starts turning it, but it only turns it for a little and then it stops, then turns it a little, and keeps doing that over and over.

A thing i have noticed is that i cant turn the proppeler, and i have heard from some people that it means that it is set in gear, and it cant start in gear. But i cant change the gear with my control box. Also when the cranck gear turns the little bit it does when i try to start it, the proppeler turns for a little aswell with it.

Things i've tried:
- Checked battery + battery poles.
- Checked ignition, its sparked small sparks so i think it works, though i dont know if the sparks have to be big, but they spark when i hold it on the metal of the cylinder.

Also, im not a boat veteran so i may

Thank you in advance, it would really be appreciated if you would take a little time to help me out.

Sincerly Mathias

Re: 1972 50HP Evinrude wont start

Is it possible that the slowing of the engine was due to overheating? Is the overheat warning horn functional? THe horn can be checked by doing the following:

Engine NOT running but have the key in the RUN position. Find the TAN wire protruding from the cylinder head and ground it to the powerhead. This completes the circuit and the horn should sound. If it does not sound, find out why as this is the only warning you'll receive before that engine seizes to a screeching halt!

Remove spark plugs. Try to turn the flywheel by hand. If you can turn the flywheel by hand, then obviously the engine is not seized now.

If the engine is not seized, remove and clean all cable and wire terminal connectors thoroughly that are associated with the electric starter which includes the actual battery terminals and the ground terminal at the powerhead, solenoid, starter, etc. Also clean the components that the cables/wires attach to.

Make sure that the battery is good and fully charged. If there is any question about the battery, replace it.

The lower unit forward gear is spring loaded, meaning the default when the engine is OFF, the unit is in forward gear (explained below).

Check to see if the engine is charging the battery..... connect a volt meter across the battery terminals with the engine not running and make a note of the voltage reading.... Now with the engine running at a semi high rpm, the voltage should increase somewhat if the charging system is operational.

(Hydro Electric Shift System Explained)
(J. Reeves)

NOTE 1 -The ohm reading of the individual shift solenoids should be between 5 to 6 ohms. The ohm meter should be set to low ohms. The shift wires leading to the solenoids must be disconnected when being tested.

NOTE 2 - The solenoid plunger measurement must be made with the solenoid placed within the lower unit. The measurement must be approximately 1/64" beneath the top surface of the solenoid... NOT above the solenoid surface nor any lower than 1/64" of the solenoid surface. This factory measurement is critical and will not ever change UNLESS someone has tinkered with it.

The shifting setup of the lower unit is what's called a "Hydro Electric Shift", which is quite complex consisting of voltage being applied to solenoids in the lower unit which in turn change oil passages via a oil pump that supplies various pressure on a spring loaded shifter dog. The wires leading to the lower unit (at the powerhead) are "Green" and "Blue". The engine must be running or cranking over in order to shift out of forward gear.

You CAN NOT use HI VIS lube in that lower unit. You MUST USE what OMC calls "Premium Blend" lube, commonly called "Type C". (A thinner lube)

Note: The engine must be running OR have the driveshaft turning by some other means in order for the engine to shift.

In neutral, you need 12v to the "Green" wire.
In reverse, you need 12v to both wires, the "Green" one and the "Blue" one.
In forward, there should be no voltage to either wire. (The spring loaded shifter dog forces the unit into forward gear)

To check the lower unit for proper shifting to make sure you have no trouble there, remove the spark plugs to avoid problems and to allow a higher cranking speed.

This next step eliminates the actual shift switch in case problems may exist there.... Disconnect the blue & green wires at the knife connectors (the rubber insulated boots) leading to the lower unit at the powerhead, then using jumpers, take voltage direct from the starter solenoid to apply voltage to the "Green" wire for neutral, then both wires 'Green" & "Blue" for reverse (Remember the engine must be cranking over in order to shift).
With no voltage applied, the unit should be in forward. No need for a ground jumper... the lower unit's already grounded. You may crank the engine with the key switch or by energizing the with a jumper wire.

Let us know what you find.

Re: 1972 50HP Evinrude wont start

Alright thank you, ill go try that as soon as i get the chance, hopefully monday. Ill let you know when i have tried it