Losing Power/ Fuel Delivery 1968 18 HP Evinrude

[mobydick]

Re: Losing Power/ Fuel Delivery 1968 18 HP Evinrude

That makes sense to me. Does anyone else have an opinion on this theory?

 

[asdasc]

Re: Losing Power/ Fuel Delivery 1968 18 HP Evinrude

Since none of my motors have fuel pumps, I am the last guy to throw out an opinion (but here I go anyway). I have read something about that on here before. It floods one cylinder and doesn't pump enough fuel.

 

[mobydick]

Re: Losing Power/ Fuel Delivery 1968 18 HP Evinrude

I hope everyone had a nice Christmas. I took a small break to releave my frustration with my motor and spend time with my family.

Today I took the boat out to try removing each sparkplug wire. I will tell you they both have enough juice to shock the fuzz out of my hair even with gloves on. I remove each, one at a time, and they both had the same dramatic effect on the motor. That is the RPMs dropped and the motor almost died. That tells me that what ever the problem is, it is something that affects both cylinders equally.

Oh so frustrating.

Thanks
greg

 

[KB1]

Re: Losing Power/ Fuel Delivery 1968 18 HP Evinrude

While you were into pulling plug wires, did you pull a spark plug one at a time to see if the water was coming out of the plug hole?!.

 

[mobydick]

Re: Losing Power/ Fuel Delivery 1968 18 HP Evinrude

I did not. I thought if water was in a cylinder, it would keep it from firing. Since the motor lost substantial power when each wire was pulled, I assumed that there was no water getting into the cylinders.

 

[KB1]

Re: Losing Power/ Fuel Delivery 1968 18 HP Evinrude

Not necassariy.

Depends on how much water is entering. It can still burn the fuel, but at a different rate of the other cylinder. A lot of hotrodders used to pour water down the carb while the engine was running to clean the carbon off the pistons, valves, etc. The reason I asked was because one spark plug looked much cleaner than the other. Top of that piston (which ever cylinder it was in) may look the same. Doesn't have to be much water to screw up the performance, but it will still burn as it is getting fire to the plug which you KNOW now is happening.

Then again it may not be this at all.

 

[outlaw241]

Re: Losing Power/ Fuel Delivery 1968 18 HP Evinrude

I have been chasing same symptoms on my 1968 18,my problems started when i put new point's an condensers in, I think one of my new condenser is bad, i think the way a condenser works is that it stores voltage and at the right time it sends it to the plug an on a bad condenser after it warms up its not storeing the voltage.i have put my old condensers back in but have not had a chance to test it in the river.

one other thing mine had a cork float an after 42 years the varnish has started to deteriorate so i put a plastic one in,those small pieces of varnish could be blocking the high speed jet at wot

hope this helps

 

[mobydick]

Re: Losing Power/ Fuel Delivery 1968 18 HP Evinrude

Well its been awhile since I posted but KB1 your were right all along.

I pulled off the cylinder head and found a small puddle of rusty water at the bottom of the lower cylinder. I looked a the head gasket and found a suspicious spot on it. I then proceeded to true the head on a cast iron table with fine emery paper. The end of the head got shiny immediatly but it took 6 sheets of emery paper and about 20 minutes to get the head perfectly flat. I reinstalled with a new head gasket and presto, it was fixed.

I now crusie in my 14ft lonestar at 24.6 mph via a gps and have reached 25.1 on glassy water. Thanks for your help and persistance. It feels so good to have finally fixed this issue.

Here is a link of the first successful outing

http://vimeo.com/8655495