I have a '77 140hp Evinrude on a stand that I picked up for cheap last fall. Winter blahs setting in so I decided to get it running. Compression is low in all four, 60 - 65 wet but at least consistent as far as I can tell. Problem showed up...when all the plugs are out it turns over fast and smooth. When the plugs are installed it barely turns, almost like it's fighting itself. There is a hefty blue spark on all cylinders and if I spray ether in the holes it will fire on one cyl. I do not have any fuel line running to it, just want to see if it fires up. a couple squirts in the carb usually does the trick for at least one go-round. A PO must have done something with timing because on the flywheel in sharpie they wrote "24deg start" with the 24deg flywheel mark and the block arrow highlighted. I know that timing should be set running at or near WOT but there has to be some initial set up. Wondering if this is the problem with the turnover situation. Battery is full, I even tried another good batt so I know that isn't the problem, all connections were pulled and sanded clean. With that low compression it should spin like a top.
Would a weak starter be the problem? how would I test that.
Good to find that in the shop and fix it before having a failure on the water. You have big water in your back yard, so now one less worry. At my age, I am not sure how many more years I can hand crank one of these big outboards with the pull rope.
Hey Bob and Mark that would be a disaster on the water.
The motor was sold as a "non runner" that sat for over 4 years. Last fall I filled the cylinders with SeaFoam and fogging oil and then turned it over by manhandling the flywheel, and let it sit a few months. Curiosity overcame the moment after the starter was reinstalled so fluid sprayed in each plug hole, (no fuel line attached), turned it over, one spin and it fired up for a second. That was both a relief and dangerous. I'm guessing after all those years of sitting the internals were pretty dry and running without mixed gas could wreck something. I did have a water muff on it though. Next is hooking up the gas line and actually do some sustained running. If it's a runner then a new impeller will go in and it will sit on the stand as a backup.