1970 Evinrude 18hp Trottle issue

[frustratedboater]

I have a 1970 Evinrude 18hp outboard bogging down issue going to open throttle. I have double checked the high speed fuel circuit and still having simular issue. I have reset the points to a snug 20 thousanths and same issue.
The engine sounds a little clunky when at idle and not real smooth, however will run at real low idle. If I throttle up all the way at 3/4 rev it will settle back down as if to stall. Is this a timing issue? I do not have a timing tool bar) like I've seen online but I've worked on a ton of these and always set the points like discussed and others ran like a dream. I'm stuck..

 

[racerone]

Post actual compression test values.----Have you inspected fuel pump diaphragm ?-----Does spark jump a gap of 1/4" or more?

 

[frustratedboater]

I'll check the compression.. New fuel pump and yes, good strong spark

 

[racerone]

The timing tool is nothing but a " dummy " flywheel and a time saver.-----You can use the timing marks on your flywheel to do the same procedure.----I missed the new fuel pump in post #1 perhaps.----Strong spark means nothing to me.----Does spark jump a gap of 1/4", yes or no ?

 

[cyclops222]

How about black & oil covered sparkplugs ? Pull all and replace them. Check that the oil is really 2 stroke. Not some leftover stuff, from someone. Bad batch of gasoline ? Or a little bit of all 3 conditions.

 

[frustratedboater]

Okay, triple checked the compresson and getting 70psi on both. Assuming they both should be 110-120?

 

[racerone]

Remove bypass covers.----Have a look at pistons and rings.

 

[frustratedboater]

Side wall:

 

[racerone]

Does spark jump a gap of 1/4" , yes or no.----May also be a leaking head gasket / warped cylinder head.

 

[frustratedboater]

Here's from my scoping tool: walls look great.. without splitting the case, and given the year, would you throw the chips on tired rings? same compression on both cyl's.

 

[racerone]

Remove cylinder head.

 

[frustratedboater]

Does spark jump a gap of 1/4" , yes or no.----May also be a leaking head gasket / warped cylinder head.

Spark jumps 1/4" on #1 & a little less the distance on #2

 

[frustratedboater]

How about black & oil covered sparkplugs ? Pull all and replace them. Check that the oil is really 2 stroke. Not some leftover stuff, from someone. Bad batch of gasoline ? Or a little bit of all 3 conditions.

I did see a little black oil, but not a lot. There was some collecting in the lower by-pass plate. The plugs had a little but not excessive

 

[racerone]

I think you have a bad compression tester or a leaking head gasket.----Remove cylinder head.

 

[frustratedboater]

I think you have a bad compression tester or a leaking head gasket.----Remove cylinder head.

I'll give it a go. I appreciate it

 

[frustratedboater]

Wouldn't water be entering if bad? Where would the compression be going..through the water passage?

 

[racerone]

You are now starting to overthink the simple procedures of trouble shooting this motor !

 

[flyingscott]

did you pull that motor at least 5 times? as fast as you could?

 

[frustratedboater]

did you pull that motor at least 5 times? as fast as you could?

Yes, I usually give it at least that to build the most pressure.

 

[frustratedboater]

Here is the head and gasket. Looks pretty solid and no signs of loosing compression.
cyclosp mentioned: black oil. What is the story behind that?