low compression

[masonh21]

Does anyone have an idea of what it would coast to rebuild a 1978 9.9 evinrude?

 

[HighTrim]

Re: low compression

Depends on alot of things.

How thorough a rebuild. Just need a hone and rings? Complete over bore with pistons? Would need much more info to give you an idea.

 

[kenmyfam]

Re: low compression

Does anyone have an idea of what it would coast to rebuild a 1978 9.9 evinrude?

More info would help. What do you deem to be low compression ??? have you tried a decarb ???

 

[masonh21]

Re: low compression

Haven't tried a decarb but compression is 74 and 80 and it seems to run good out of water but when in water it is very weak and sounds like its bogged down. Not sure how far to go with rebuild hopfully just enuf to get compression back.

 

[kenmyfam]

Re: low compression

Haven't tried a decarb but compression is 74 and 80 and it seems to run good out of water but when in water it is very weak and sounds like its bogged down. Not sure how far to go with rebuild hopfully just enuf to get compression back.

Running good out of water and badly in the water could be a multitude of things. Considering a rebuild at this point could be a waste of money and time. You need to give the motor a good basic health check to begin with.

Compression (you have done already but check it with a different gauge)
Spark
Fuel delivery
Spark plug condition

Use the "Top Secret Files" at the top of page #1 of this section to help you and I would suggest an OEM manual.
I am suspecting you are losing a cylinder when in the water and under load.
Good Luck and post your results for all to see.

 

[AlTn]

Re: low compression

FWIW...fish with a friend almost every weekend...1978 9.9..80ish lbs. compression...13 ft. vhull aluminum monark...planes 370lb. of flesh, 2 deep cycle batteries, trolling motor, and at least 50 lb. of other "stuff"...I'm with Ken, check for spark loss,motor set up,weight distribution, etc.

 

[JB]

Re: low compression

Your problem is not compression and she doesn't need an overhaul. Though the cylinders would probably get closer with a decarb, anything over about 60 psi is okay in a rope start outboard.

 

[masonh21]

Re: low compression

I have put new spark plugs in it and its getting fuel I have also checked the spark but it does sorta seem like its only running on one cylender in the water... it has kicked in and ran right one time in the last 2 years for the whole day then next time in the water it was back to the same thang does anyone know what would cause that?

 

[AlTn]

Re: low compression

It could be as simple as a bad ground or plug boot/connector...to coil..powerpack. The free and simple stuff is to clean every ground <coils, powerpack> disconnect each connector and clean the male ends and female sockets with rubbing alcohol.Next, purchase a dry gap spark tester at an auto parts store $10 or so...set it at 7/16" gap and test each plug wire...each one should jump this gap. Post back your results and we'll go from there. A factory workshop manual is a great asset if you're going to work on this motor.

 

[kenmyfam]

Re: low compression

I have put new spark plugs in it and its getting fuel I have also checked the spark but it does sorta seem like its only running on one cylender in the water... it has kicked in and ran right one time in the last 2 years for the whole day then next time in the water it was back to the same thang does anyone know what would cause that?

Well we are back to that "basic health chek" mentioned in post #5 are we not ???

 

[Sixmark]

Re: low compression

Looking for the quick fix often only leads to a quick breakdown as well. It really is worth going through the basics tests and inspection for multiple reasons. You might find something you overlooked while thinking of the quick fix, and you get to learn more about your motor than you thought you would.

 

[masonh21]

Re: low compression

I done a decarb on the engion. it is fireing good on both cylenders . II put new spark plugs in it and made sure it was getting fuel and had the carb cleaned but its still very weak in water it wont plane out my 14 ft john boat. I put a friends. 9.9 evinrude on it and it jumped right out of the hole no problem

 

[kenmyfam]

Re: low compression

I done a decarb on the engion. it is fireing good on both cylenders . II put new spark plugs in it and made sure it was getting fuel and had the carb cleaned but its still very weak in water it wont plane out my 14 ft john boat. I put a friends. 9.9 evinrude on it and it jumped right out of the hole no problem

How do you know it is "firing good" on both cylinders ???

 

[masonh21]

Re: low compression

I pulled the plug wires off and stuck a screw driver in the end and pulled it and it had blue spark on both... is there a better way to check it to know for sure?

 

[masonh21]

Re: low compression

I noticed that both coils have a small crack in them could this be causing the problem

 

[Tim Frank]

Re: low compression

I pulled the plug wires off and stuck a screw driver in the end and pulled it and it had blue spark on both... is there a better way to check it to know for sure?

Yes. A dry gap spark tester....as was suggested a number of posts ago.

 

[bktheking]

Re: low compression

Replace crack coils for sure. I leaned that having spark doesn't mean much, does the motor sound the same as your buddies motor? Mine had spark and was only firing on one cylinder, later discovered a zip tie stuck in the reed plate. How do the plugs look? One oily one not? Could be water intrusion as well.

 

[masonh21]

Re: low compression

I have done some more reading on other forums and I have found ppl with the same problem as I have and high speed jets seemed to be most peoples problem so im gonna clean the carb again and really concentrate on the high speed jet and maby that will be it

 

[AlTn]

Re: low compression

have you checked the link%sync on your motor?...the roller on your linkage should just be touching the timing cam mark as the throttle plate in the carb throat begins to open. At wot <wide open throttle> the roller should be at the highest part of the cam and the throttle plate should be perfectly horizontal in the carb throat. Compare your linkage set up to your buddy's motor. Diagrams for your motor can be found at marineengine.com, boats.net, crowley marine, and other sites. A wealth of info and pics is provided byThe Machinist at his site..sschapterpsa.com..Leeroy's Ramblings 9.9 and 15 hp maintenace and repair.