# Problem with 70 HP Evinrude Outboard



## rlk

I posted this on NewBoatTalk as well.  Hopefully I'll get some suggestions.

Yesterday morning my 70 HP Evinrude outboard ran great for about a half hour.  After running for a half hour at 3500 RPMs, the engine started sputtering and coughing. It sounded like there was water in the gasoline. The engine RPMs would drop from 3500 to around 1000, sputter/cough, then jump to 2500. Sometimes the engine would just shut off. I was able to get back to my dock by pressing the choke button when the RPMs would drop to around 1000. The RPMs would pick back up to around 2500, and it would run for a second or two, then sputter/cough and the RPMs would again drop to around 1000. Pressing the choke button would usually work, but several times the engine just stopped. It would always restart right away, but as soon as you gave it gas, it would start sputtering/coughing again. 

Thinking the engine may have overheated, I checked to ensure there was water coming out of the engine. The water stream was warm, but not really hot, so I'm thinking it is not overheating. The horn in the console that is supposed to sound when the engine overheats never sounded. 

Each time the engine quit, it restarted easily. 

Once I got back to the dock, the engine started and idled great. 

Figuring this was water or trash in the fuel, I bought a new 6 gallon gas tank and hose. Filled the tank with fresh gas, and tried again today. 

Same thing happened again - the first half hour the engine ran very well, then the sputtering/coughing started again. Once again we limped back to the dock by occasionally pressing the choke button. 

I have had the carbs rebuilt; had the timing set; new plugs installed.

Anyone have any idea what the problem may be?

Thanks, Bob


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## DaveNay

We had a very similar problem with one of our boats last year fishing in Canada.  The reed valve was starting to fail.  Is yours a two stroke?


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## rlk

DaveNay said:


> We had a very similar problem with one of our boats last year fishing in Canada.  The reed valve was starting to fail.  Is yours a two stroke?



Yes, it is a oil injected 2 stroke with 3 carbs.

Thanks, Bob


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## rlk

Bump.


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## fogtender

Normally if a seal or reed starts to go bad, they don't get better then worse again, they fail and just quit working, but there is the off chance that they "May" be causing the problems. On the Evinrude, they are directly under the carb and are easy to remove and check. On a Merc, they are located around the Crankshaft and result in total disassembly of the engine, which amounts to basically getting it overhauled.

But before you go and check the reeds, you have pretty much established that it is a fuel issue. You said that it was just rebuilt? I would go and check on that work first, just because it was "rebuilt" that doesn't mean it was done right.

It sounds like it can be dirt in the fuel clogging a fuel jet, you can drain your fuel bowls though a paper towel to see if there is any "Debree" in them. If you have so much as a spec of dirt in them, that can be an issue to chase down. 

There is a number of issues that will cause the same problems. One can be as simple as a faulty key switch that shorts out part of the electrical system intermittently, but fuel appears the issue.

If you have a seal or reed going bad, the engine will only idle on one or two cylinders and as you speed up, it will studder then kick into a full throttle mode as the "Dead" cylinder kicks in, and when you idle down a bit, the cylinder will drop off again and by the description you gave, that didn't seem to be the issue..

To be a bit more help, what year and model is the engine, two or three cylinders, that would help a bit, other than being generic. Fuel injected or carb's, even a photos of the engine assembly would help.


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## fogtender

OH, you need to check your fuel filter/screen too...


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