Home Forums Hunting & Shooting Hunter's Campfire Since no boat forum and most traffic here, a question

I have an older 50 HP Johnson (78 I think) on a party barge, that runs fine hooked up to the water ears and sitting in my yard, but at the lake it starts and dies, starts and dies. I can't even back it off the trailer. We went to try it out day before yesterday and it would not run at the lake, except starting in forward gear and it seemed to work ok, but in neutral or reverse it was start and die. I recharged the battery yesterday and just a few minutes ago tried it. Started in neutral, ran a little bit, put in reverse and worked like a champ. This system has the throttle and gears on the same lever so you can not give it more fuel in neutral. Is there anything that hauling should mess up, or maybe the angle it is on the trailer at the boat ramp? Also, sitting in my yard there is no torque when in gear, could this be a problem? Thus boat is new to me so I don't have a clue. Should add that it has a new fuel pump on it. miles

If you are running E10 it is most likely an ethanol problem. I have had similar problems where boats ran fine on muffs but when run under load would sputter and not get up on plane. Carb rebuilds always solved the problem. The water absorbed by the ethanol in E10 gas loves to clog up carbs, it also can dissolve some plastics and rubber parts and lines in older engines. My boat mechanic jokingly says that E10 is the best thing that has ever happened for boat repair shops. If you cannot get pure gas, look online and there volumes of tips to try and minimize the effects of E10.

Right, but before you get into the engine, check your fuel lines. Ethanol eats them up and causes them to collapse. This can be checked easily by pouring a little fuel directly into your carburetor while it's idling. I replace my hoses every year now.

Check your throttle lever. You should be able the pull the lever outward about 3/8" and push forward. This allows you to put the throttle in fast idle without engaging the prop. Your key switch should also push in to prime the fuel system.

The correct starting procedure is to trim your motor level, pump the bulb on your fuel line until firm, place throttle lever in fast idle (approx. 25% throttle), then push in on the key switch while bumping the starter. If the motor tries to die, push in on the key switch (primer) again to give it more fuel. Let idle a few seconds until it is running smoothly, then shift into gear.

This model has a lever that you raise for a cold start. I don't think that it has a way to pull the throttle lever out but I will look. I also don't think pushing the key in does anything. It does have a toggle switch for an eletric choke. Trim is manual using a rod through holes not electric. miles

I am using gasoline with a little ethanol in it. I mixed new gas in a clean tank and added seafoam. I also have a brand new tank and line that I tried, with the same result. miles

I just checked, it is a 1971 Johnson. miles

Sounds like the carb then.

Sorry Miles, I read your post to mean you didn't have a cold start lever.

Since you mention it starting right fresh off the charger:

I was having a similar problem with a '91 Evinrude 40. Would start fine on muffs in the yard, would be a major hassle to start at the ramp after a 60 mile trip. Turned out to be a bad battery. These older motors have to crank at pretty high rpms to cold start. Check your battery to see if it's good, and also make sure it's a cranking battery and not a deep cycle. I was also having an issue with the rectifier on the motor (the reason my 3 month old battery went bad)so I replaced it and have had no starting issues since.

Could be sucking air in a fuel line under a load and run fine when not actually under load. I like to change the fuel lines every couple le of years just in case.

Does it sputter a bit before it dies? It sounds like you may have a pin hole in the fuelnile and its sucking air?

You also probably need the carbs cleaned and sync'd.

You might have some water in the fuel tank that gets picked up at the ramp or as the boat rocks and pitches. Sitting stationary in the yard doesn't slosh the fuel around, and you might not be picking up the water there.

IS THE GAS TANK VENT OPEN?

Hahaha...It wouldn't be funny if I hadn't done that. "Sometime's it's the simplest things".

Yes. I will add that the battery is just a year old and was put on this boat when I first got it. I have been working on seats and lights. I took it to the lake late last summer to try it out and it started and ran fine, at first, and then started to run rough. Brought it home and the fuel pump had a crack in the plastic body. I replaced the fuel pump and this is the first time I have tried to do anything since then. miles

Cleaned the carbs last year with the help of my neighbor that is a pretty good shade tree mechanic, and set them according to internet instructions. miles

I should add that I know a good boat motor mechanic, that if it is not something trivial, I will take it to. Problem is, he is most likely covered up this time of year and the wait will be long. miles

How would one check this? I can get a new one if needed. OMC is $38.00 and and aftermarket is $25.00. miles

Do you have a way to put the motor in a tank and run it? The water ears might be pushing water through but the pump might not be able to pull it through when it's in the water.

I've had several Johnson/Evinrude outboards over the years. Older models had fuel lines that were not compatible with ethanol fuel. The line will look fine on the outside, but take a fuel line off under the engine cowling and let a little of the gas dribble on your finger. You'll likely find a black coloration mixed in with the fuel. That's the inside of the fuel line rotting out. You'll need to replace every single fuel line, including those small ones that run into the carb. And don't forget you'll need a new line from your gas can to the outboard. Carb overhauls are common for older outboards, so if yours hasn't been done in awhile, you're most likely due for a rebuild. Finally, Johnson/Evinrude outboards worked on a closed fuel system, i.e. there is no vent on the gas cap on an OEM tank. After those items, since your outboard is a 1971, you still have points and condensers. It may be time for a tune-up.

On edit: Not seeing where you put a new set of spark plugs in it. Make sure you have new plugs in the engine.