What is this???

[ddavis90325is]

My 1984 35hp Evinrude is running on one cylinder. I have 130lb of compression in each cylinder, and i have spark on both cylinders. I re-built the carb and fuel pump and it's still running on one cylinder. One thing that i think may be causing the problem is this so called "electric primer" which would be the electric choke.

It effects how the engine runs when i turn the red switch on the top of the unit. What exactly is this, and could this be what is causing my engine to run on only one cylinder? Thanks!

 

[wbeaton]

Re: What is this???

That red switch is for manual starting. If you turn it on when you are running, all it will do is flood the engine, which may seem like you are running on one cylinder.

 

[tashasdaddy]

Re: What is this???

try swapping the spark plugs first. see if the problem follows the plug. if not swap the coils. that is if you are positive the carb are clean and rebuild kit was used.



if the red valve is in the 6 oclock position, the primer is letting gas into the intake flooding the motor. it should be like the picture back center line with the body. that's why it is flooding out. this should cure your problem. let me know.

the primer replaced the old choke butterflies in the carborators, pushing in the key activates it, like the old choke plates.

 

[ddavis90325is]

Re: What is this???

Well here is what it did this time, which makes me think fuel pump, but i just re-built it and i'm pretty sure i did it right.

It starts up, but only with the electric choke to the manual position, when the red switch sits perpendicular to the whole unit. Then, when i put it into gear and accelerate, it goes to one cylinder and loses power. This definately has to be a fuel supply issue...

I re-built the carb last year and it ran great till the last day of duck season then it dropped to one cylinder. I took the carb apart this spring and just rinsed it wish solvent and installed a new impeller, and ran it for 4 days on Lake Michigan. I then ran it for two days on the Mississippi River with no problems.

The day after getting back from the Miss, it dropped to one cylinder on my local river, and then wouldn't even start. So i pulled the fuel pump and installed a new pump, and pulled the carb and cleaned it again. I have a test of 130psi cold on both cylinders and both cylinders have plenty of spark.

Thanks for all the help already!

 

[jay_merrill]

Re: What is this???

Having a fuel pump problem wouldn't make the motor run on one cylinder. On the other hand, it might starve the carb for fuel and that would make the motor "bog down." I'm thinking that your motor isn't really running on one cylinder and that you are misinterpreting the symptoms. On the other hand, it may well be a fuel supply problem. Just keep trouble shooting the motor from that perspective for a bit. The "spray bottle trick" (spraying some premix into the carb) may help you diagnose the problem - if the motor runs better when you do this, you have fuel delivery issues and either the fuel pump or carb are prime candidates.

 

[ddavis90325is]

Re: What is this???

Well the reason i am thinking it runs on one cylinder is becuase when i remove the spark plug from one of the cylinders, it runs the same, then when i take the other one out, it won't even start. i can't remember which one is not firing, but i know one of them isn't.