HELP 1968 7.5 evinrude PROBLEMS

[jonoman69]

I have a 7.5 1958 evinrude. And I cant figure out what the problem is with it. First off our biggest problem was that the person who had it before thought the fuel mixture was 50 to 1, but it wasnt ran much on this mixture, and was ran very little back in its day. Anyhow the problem is this.... We can get it to run fine set it up in a bucket with water, we had it idling for over half hour, rev it up a bit, it works good. But heres where the problem starts, we go down to the lake with the boat and motor to try her out in the water it starts up fine no problems, but when you put it in gear it runs fine but when you go to give it more throttle the engine doesnt really rev up and has no power, or its fighting something, either way it wont rev high up withthe gas and the speed doesnt change lol.

Then what happens is when you drop the throttle, it dies, wont start again for a while, and sometimes you cant pull it. Its almost like it seizes, but if you let it sit or take the coil off and play with the top end you can spin it backwards till spinning it proper frees up. I dont know a whole lot about this stuff havnt really looked at it yet, sorta looking for starting points. thinking maybe something jamming the gears, hoping nothing major lol.

Sorry for such a long confusing blog here, but i need help and any ideas or thoughts would be greatly appreciated. thanks Jon

 

[18rude]

Re: HELP 1968 7.5 evinrude PROBLEMS

Have you checked the compression?

 

[mikesea]

Re: HELP 1968 7.5 evinrude PROBLEMS

.Check that the timerbase under the flywheel is moving properly along with the carb getting throttle.If the timing sequence is off that could be a problem as you mention.That eng might have a locking device on a thin rod that allows throttle pickup .It may be a brass barrell with locking screws.Have you ran the engine with 25-1 ratio.I think?the extra oil helps with the compression.I once had an old engine and tried 50-1 it ran poorly.When i introduced the 25-1 it ran ok.Coincedence?the experts will know.If your problem is not as mentioned,I would check the carb for dirty internal passages cleaned only by removal and soaking.What kind of fuel tank.Is it external?if so is it double line?you may have a blockage in one of the double lines.Thats if its a fuel problem.That is a 2 cyl.you could have bad coil(s) whicch is very common in the older engines.they break down under load.pop the flywheel,inspect for cracking of the potting material around the coils.If you see cracking,I would change the coils.They are sold perhaps through iboats store.If not thay are not hard to find.You can do a spark test .You will need a tester.Simply grounding the plug is not a good enough check.Especially for the older points/condenser-coil engines.