1960 40 HP Evinrude Lark Twin Stalling Out Request for Help
Hey Folks:
I recently bought a 1960 wood runabout with a 1960 Evinrude Lark 40 HP Twin and I am having some trouble making it run well and I am hoping for a little help. The boat/motor is in great shape, always garaged, only used a few times a year in freshwater, owner said he had great luck with it and ran the carb dry after each use to keep it clean.
Based on the parts included, it looks like the lower end was replaced once due to an accident, the carb was rebuilt and the water pump, and points were also replaced at least once.
When I bought it the previous owner- who said it always ran well for him and I believe him- ran it for a few minutes in a barrel but I was worried that it wasn’t spitting enough water so we shut it down and I took it home and changed the water pump impeller. The existing pump was fine, stiff but intact, so I replaced only the impeller, because the metal plate and the other seals and o-rings seemed okay.
On the first day on the water last weekend, it ran for 2-3 minutes at a time, spitting some water out of the upper exhaust port (a little more than a good spray bottle spits out) but then it would shut down and not restart until after 10-15 minutes. We did about four cycles of that before getting towed back to the launch and calling it a day. I had carefully mixed the gas at 24/1 as instructed in the manual and the gas was brand new high octane, albeit ethanol mixed, so I don’t think that was the problem.
At first I thought it may be fuel starvation, so I pumped that primer bulb some while it was running to see if that would help. The bulb grew soft every thirty seconds or so, but didn’t seem to run better or worse when pumped even though it did push some more fuel and bubbles into the glass sediment/filter bowl. The carb didn’t look like anything was amiss, no overflowing bowl etc.
I was also worried that it was overheating on these test runs so I removed the engine cover and spritzed some water on the heads. It sizzled a little and steamed away, but didn’t seem like it was red hot and the paint wasn’t bubbling or anything that would suggest serious overheating. Each time it stopped, I cranked it over to see if it would start. With the exception of one time, it always cranked over readily but wouldn’t start. On one occasion, after a bit of a longer run, it wouldn’t turn over and I worried that I cooked it/seized it, but a few minutes later it turned over again readily so … at worst I may have soft seized it or … I am not really sure.
Finally, I wondered if I was losing ignition due to an overheated condenser, coil, etc., but I didn’t have an ignition test light with me on the water so I couldn’t really check that very easily.
When I got it back home I pulled the plugs to check condition. They were dry, a little more gray than that brown that I’d like to see on a two stroke, but not bad overall. I also checked the compression. It was 95 in both cylinders using the starter motor and turning it over about 5 times. But, my tester wasn’t sealing perfectly so I suspect it has a little north of 100 pounds per cylinder.
At this point, I guess I’ll set it up in a barrel and see if it is losing ignition when it heats up. If that isn’t the problem I guess I’ll look into fuel delivery via the pump and perhaps carburation.
Any suggestions are welcome and my questions are these:
Thanks in advance –
Neil
Hey Folks:
I recently bought a 1960 wood runabout with a 1960 Evinrude Lark 40 HP Twin and I am having some trouble making it run well and I am hoping for a little help. The boat/motor is in great shape, always garaged, only used a few times a year in freshwater, owner said he had great luck with it and ran the carb dry after each use to keep it clean.
Based on the parts included, it looks like the lower end was replaced once due to an accident, the carb was rebuilt and the water pump, and points were also replaced at least once.
When I bought it the previous owner- who said it always ran well for him and I believe him- ran it for a few minutes in a barrel but I was worried that it wasn’t spitting enough water so we shut it down and I took it home and changed the water pump impeller. The existing pump was fine, stiff but intact, so I replaced only the impeller, because the metal plate and the other seals and o-rings seemed okay.
On the first day on the water last weekend, it ran for 2-3 minutes at a time, spitting some water out of the upper exhaust port (a little more than a good spray bottle spits out) but then it would shut down and not restart until after 10-15 minutes. We did about four cycles of that before getting towed back to the launch and calling it a day. I had carefully mixed the gas at 24/1 as instructed in the manual and the gas was brand new high octane, albeit ethanol mixed, so I don’t think that was the problem.
At first I thought it may be fuel starvation, so I pumped that primer bulb some while it was running to see if that would help. The bulb grew soft every thirty seconds or so, but didn’t seem to run better or worse when pumped even though it did push some more fuel and bubbles into the glass sediment/filter bowl. The carb didn’t look like anything was amiss, no overflowing bowl etc.
I was also worried that it was overheating on these test runs so I removed the engine cover and spritzed some water on the heads. It sizzled a little and steamed away, but didn’t seem like it was red hot and the paint wasn’t bubbling or anything that would suggest serious overheating. Each time it stopped, I cranked it over to see if it would start. With the exception of one time, it always cranked over readily but wouldn’t start. On one occasion, after a bit of a longer run, it wouldn’t turn over and I worried that I cooked it/seized it, but a few minutes later it turned over again readily so … at worst I may have soft seized it or … I am not really sure.
Finally, I wondered if I was losing ignition due to an overheated condenser, coil, etc., but I didn’t have an ignition test light with me on the water so I couldn’t really check that very easily.
When I got it back home I pulled the plugs to check condition. They were dry, a little more gray than that brown that I’d like to see on a two stroke, but not bad overall. I also checked the compression. It was 95 in both cylinders using the starter motor and turning it over about 5 times. But, my tester wasn’t sealing perfectly so I suspect it has a little north of 100 pounds per cylinder.
At this point, I guess I’ll set it up in a barrel and see if it is losing ignition when it heats up. If that isn’t the problem I guess I’ll look into fuel delivery via the pump and perhaps carburation.
Any suggestions are welcome and my questions are these:
- Does this motor have an overheating shutdown switch to protect it (so it doesn’t sieze)?
- How much water should come out of the upper exhaust port when the pump is working properly, does some also go out the bottom of the engine under the water?
- Is this motor supposed to pee a steady stream out any little holes in the side of it like more modern outboards do to tell you the water pump is working (mine didn’t)?
- Does this motor have a fuel pump that I should be considering to see if it is being starved of fuel?
- Is the primer bulb supposed to stay hard during normal operation or should it go soft?
- Is 95-105 pounds per cylinder enough compression to allow this motor to operate correctly?
- Any hunches as to the problem based on what I’ve shared?
- Any other suggestions about places to look next to diagnose the problem?
- Is running it in a barrel in gear a problem for the motor/dangerous?
Thanks in advance –
Neil
