Just upgraded pontoon boat from 40 to 70hp. Everthing fit and hooked up the same, great. Hooked up my fuel tank and a set of muffs cranked it about a half revolution and it started, great. Didn't see much water comming out shut it down after 20 sec. Replaced impeller assembly restarted engine pumped plenty of water now. Headed for the lake a few days later to try the used engine on a run around the lake. Backed the trailer into the lake the engine cranked quite a bit before it started ran it around the lake probably 4 miles and it ran great. Quiet, smooth and powerful, great. Tied it up to the dock for a week or so until I had a chance to take another short trip. The engine cranked quite a bit before it started but it ran well for a mile when it sneezed a little at speed. Docked it again for aweek and ran it again today. Cranked a fair amount to get it started ran a mile down the lake and she quit as suddenly as if I cut the ignition. Cranked it back up after a few mins. and went about 500yds, it quit again. Finally restarted headed for the dock. Played with it for a little and it acts as if it runs out of fuel. Probably runs until carb bowls empty and dosn't restart until they refill. Before I head off it the wrong direction what should I look for that cause these symptoms? I'm a fairly skilled tech having worked on golf carts and grounds equip for years but outboards are another creature and I bought this used.
The first thing I would do is rebuild the carbs.....especially since the motor was used and you probably don't know when it was done last. If it sat for a period of time or wasn't stored properly you could have varnish problems.
Even if that isn't the issue it would be a good thing to do/have done.
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I have a fuel filter just past the coupler, is it possible that I have water or crud enough in there to slow down fuel flow? Also the primer dosn't always get hard, as if it pushes past the needle valves. I know your right I should pull the carbs apart. As with most folks I hope for the easy cure. Could seafoam help or should I stay away from additives? Could a fuel leak cause my problem?
Shutting off like you turned the key, instead of sputtering to a stop like when you run out of gas, sounds kinda like a spark problem. Spark test immediately after it shuts down would tell.
But if the primer bulb goes soft, that's a problem in and of itself -- it needs to get firm & stay firm all day. If it collapses (won't open back up) when you squeeze it while the engine's acting up, that indicates a restriction upstream of the bulb.
Leaky float valves will flood the engine -- if you prime the line then tilt the motor up far as it will go, and see gas coming out the carb throats, or if you can force gas out the carbs with the primer bulb, that'll confirm leaky valves. Only a rebuild with new kits will fix it.
Seafoam is great stuff, I use it in every tank, but it won't cure what you've got. I agree with pony, carb rebuild on a newly acquired used motor makes a lot of sense. You'll be surprised at how simple these carbs are -- don't be intimidated. But do get yourself a service manual.
If you don't have compression numbers on the engine, this would be a good time to do it -- as a baseline for future diagnostics if nothing else.
and welcome to the forum!
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4th of July, time to celabrate. I finally got back to the lake to mess with my motor. I pulled the carbs and found them spotless. The floats and needle valves seemed to work as I would expect. I reinstalled everything and replaced the tank to motor fuel line just because I had one. I had to push this one on the motor with much more effort, primed the bulb which to a little, I assume to refill the dry carbs, cranked it and it fired up. Eased the boat away from the dock hit the throttle and away we went. This lake is about 1.5 miles long and we did six laps without skipping a beat. Ya think I got it beat? Anyhow thanks for you insight. I'll continue to watch this board, and I'll update if things change. Thanks!
Not many engines use the removable fuel hose anymore.What likley happened,is the oring inside the connector went bad.They are replaceable.The eng.sucks air ,instead of fuel,the rest is obvious.Have a happy July 4th weekend.
96 Evinrude 70hp stalls
Linear Mode
