1975 Evinrude 70 hp backfiring

[mav6759]

I have a 1975 Evinrude 70hp, the problem that I am having is when I try to start the motor, the motor backfires like a shotgun being fired. I also noticed that the crab's are leaking gas down into the bottom of the eigine pan. I do have to admit, I have the motor tiltted forward. Also I have a problem with motor continuing to turn over even after the switch is off. Which mean to tell me I have a wire touching somewhere, either out of the control box or on the motor. Could the backfiring because I have the motor tilted forward and the gas is running out of crabs or could the motor be gettting to much gas. As for the continuing running I have no ideas, it does not do it all the time just sometimes. I'm going to open the controls and see if there are any bad wires or the switch.

 

[Daviet]

Re: 1975 Evinrude 70 hp backfiring

Why are you starting the engine with it tilted? Does it start properly with the engine down in the normanl position?

 

[mav6759]

Re: 1975 Evinrude 70 hp backfiring

I'm starting the motor or a tilt because, I am starting the motor on muff's trying to work out the bugs. Other then that it starts and runs. I was on the lake the other day and it ran great. But on my a move the motor just die. I get it back home and it started right up. I believe the motor is flooding. I pulled the plugs and the plugs were filled with gas, I put a match in the plug hole to burn off the gas in the cylinders and once I got all the gas out the motor ran very well. Should I be trying to start the motor on a tilt.

 

[mrcj001]

Re: 1975 Evinrude 70 hp backfiring

The carbarators are flooding. Foats are sticking. Time to rebuild them.

 

[Daviet]

Re: 1975 Evinrude 70 hp backfiring

I don't think you ansewered my question, will the engine run properly when the engine is in the normal position (down).
How far do you have the engine tilted, you have carbs and floats, they are only made to run at certain angles.

 

[mav6759]

Re: 1975 Evinrude 70 hp backfiring

I do have the engine in an angle because I have it in my driveway, and it runs very good when it is down. The issue is I can't keep it running in that position. I pulled the spark plugs and I don't know how to tell if they are bad. They don't look like regular spark plugs, they don't have that tip like regular plugs.

 

[Daviet]

Re: 1975 Evinrude 70 hp backfiring

It seems to me that if the engine runs properly in the down position, you are causing you own problem. Carbs have floats designed to run at certain angles, if you exceed those angles they cannot preform properly.
If you don't have enough clearence try dropping the hitch coupler down as low as it will go and that will raise the stern of the boat, and maybe give you the clearence you need to lower the engine to the proper running angle.