1968 Evinrude 40 with no power

[Netwatchers]

I read another post where "The admiral" asked the poster about the condition of the spark plugs,..mine are both black tipped and oily. Oil also drips out the bottom (water intake?) just above the prop. Would that affect the performance. It barely pushes a 13 footer 10 knots. What are the signs of broken head gasket, carb problems, low or no compression?

 

[DJ]

Re: 1968 Evinrude 40 with no power

1. Head gasket. One plug, or both, will be washed clean. Not your case.

2. Black-sooty-overfueled. Carb in need of rebuild, or, over riched on the adjustments. My feeling is the prior.

3. Oil will drip, since you're running it so fat.

I doubt you're hitting on both cylionders. Do a spark check.

When is the last time you did?

1. Points. Gap to .020"

2. Plugs (CHAMPION-ONLY) gapped at: .030 t0 .040."

 

[Netwatchers]

Re: 1968 Evinrude 40 with no power

1. Head gasket. One plug, or both, will be washed clean. Not your case.

2. Black-sooty-overfueled. Carb in need of rebuild, or, over riched on the adjustments. My feeling is the prior.

3. Oil will drip, since you're running it so fat.

I doubt you're hitting on both cylionders. Do a spark check.

When is the last time you did?

1. Points. Gap to .020"

2. Plugs (CHAMPION-ONLY) gapped at: .030 t0 .040."

 

[Netwatchers]

Re: 1968 Evinrude 40 with no power

Thanks, I think I will get a carb rebuild kit and a couple new spark plugs to start,...Anyone know the part number for the carb? Its a 1968 Big Twin 40 horse. Any suggestions on where I can get it?

 

[F_R]

Re: 1968 Evinrude 40 with no power

I don't think you read what was written previoulsy. He said he doubts your motor is running on both cylinders. So do I. That is the cause of low power 90% of the time. It is dumb to go digging into the carburetor before checking the obvious....unless you just want to learn about carburetors.

You should:

1. Start the motor and short out one spark plug at a time. Does the rpm change approx the same amount on each? Or does it make no difference on one and the other kills it? The one that makes no difference is the one that is not working and your repair attempts need to focus on that one.

2. Check the compression first. This will save you a whole lot of unproductive work and $ if there is a problem. Proceed only if the compression checks out good.

3. Don't just look at the spark plugs. Test the spark. It should jump a 3/16-1/4" gap. Jumping a .030 gap across the spark plug laying on the head is not a spark test. Neither is holding it in your hand to see if your eyeballs light up. If you don't have adequate spark on both wires, stop jerking around and find out what is wrong. Also don't assume the spark plug is good...replace it if any doubt at all.

4. A ruptured fuel pump diaphragm will cause a motor to run rich on the cylinder to which it is attached.

5. Carburetors DO NOT make a motor run on one cylinder....unless there is more than one carburetor, which is not the case here.