Johnson 9.9 still having issues..

[kpresley84]

hi all, i have a 1977 johnson 9.9 and it has been running rough since i got it and i'm still trying to diagnose the problem...the motor will idle ok, its when i give it gas to go all it will do is bog down and not hit any rpms...the first time i checked the plugs the top one was clean and the bottom one looked fouled out..so i checked for spark and the top one was real weak...so i replaced the powerpack and cleaned the carb. and took it out and it is still doing the same thing...same for the plugs, top one was clean and bottom looked fouled out..i'm thinking coils now, but i'm no expert by far...carb should be ok, it was clean as a whistle...i checked the compression and its all good...i did notice when i took it out today that there was a weak "pee" stream...i'm going to replace the water pump, but would that have any effect on the issues i'm having?? Any help on what is going on here would be greatly appreciated!!! Thanks..

 

[kpresley84]

Re: Johnson 9.9 still having issues..

HELP!!!!!??????????

 

[rnli rich]

Re: Johnson 9.9 still having issues..

have you run compression test? results should be 100+ and within 10% of each other, doing these test will tell you the condition of the engine block, also your headgaskets could be leaking/worn, could be why its ok on idle then when you give it big guns no revs, the pressure built up could be leaking through this gasket, are you using fresh gas???
id leave the water pump till you have sorted this issue out, it is pumping you say,so leave it for now.

goodluck, i was having simular problems with my 7.5, i changed the plugs,fresh,correctly mixed gas in her, run a compression test,changed a few gaskets and now she runs like a dream- now im trying to sort my water cooling system out!! got a nasty blockage on my inlet pipe

 

[kpresley84]

Re: Johnson 9.9 still having issues..

yes i have run compression test...had about 80# on both cylinders..there were equal so i figured thats ok..i will check the head gaskets today and see if maybe that is it..and yes there is fresh gas and oil in the tank...you guys don't think it could be a coil? being that the top plug is cleaner than the bottom one?? and as for my water pump it is just "spitting" water out...not a good stream like it should be...does that not mean it is going out? Thanks for your time and help..any more advice would be appreciated!! Kenny

 

[kpresley84]

Re: Johnson 9.9 still having issues..

http://i225.photobucket.com/albums/dd126/kpresley84/plugs.jpg
These are my plugs...The top one is competely clean and the bottom one looks fouled out...i'm pretty sure this is my issue...What would make one fire and one not?? Coil?? any advice would be great!!

 

[steelespike]

Re: Johnson 9.9 still having issues..

Comepletely clean plug is an indication of a bad head gasket.Water steam cleans the plug.

 

[kpresley84]

Re: Johnson 9.9 still having issues..

i looked at the head gasket...i myself didn't see any leaks, but i'll have someone else look also..steelespike, what you are saying kinda makes sense because when i took that clean plug out it was dripping(smelled like water/gas)..if the gasket is bad, why is just one of them clean?? Would you guys rule out a coil and try the gasket first or what?? thanks yall the help is greatly appreciated!!! I have knowledge of motors, just not boat motors...Thanks again!!

 

[kpresley84]

Re: Johnson 9.9 still having issues..

But....would having 80# of pressure at both cylinders not eliminate the head gasket as being the problem??? just a thought...

 

[kpresley84]

Re: Johnson 9.9 still having issues..

any advice??

 

[Kflc]

Re: Johnson 9.9 still having issues..

Firstly, if the water pump is spitting a stream out , your impellor needs replacing. Poor water flow through the block will always cause the top cylinder to run hot as the water runs from bottom to top and this hot running will give the clean top plug scenario as the top plug and cylinder is so hot the soot does not deposit on it. You may also only have a gasket leak on the top cylinder hence the one dripping plug scenario. If it has gone this far you probably do have a gasket leak now for which you should pull the head off and replace the gasket- they are not expensive. When you replace the gasket, just make sure the block and head are perfectly clean and flat with no corrosion and do not use any sealer as the gasket has heat glue on it. (EDIT) check the resistance of the coil, it should be the same as the good one. if that cylinder is not firing because of a weak spark, the plug will stay clean and will be wet as it hasn't burn't the fuel!

 

[kpresley84]

Re: Johnson 9.9 still having issues..

thank you Kflc that is very helpful info...i didn't understand your answer on the head gasket thing, even though i have the same compression on both cylinders i could still have a head gasket leaking???? I am going to replace the water pump, do i need to replace it all or just the impeller??? and also how do i check the resistance of the coils??? Thanks again for the helpful info!! Keep it comin!!!

 

[rupertmja]

Re: Johnson 9.9 still having issues..

Water pump = impeller = the same thing. THe coils have resistance that can be checked with an electronic test meter - not expensive to buy at all. If the resistance is the same then both coils are the same, i.e., one is not broken. If one is significantly different it may be suspect. Then, it would be wise to find out what the resistance is supposed to be and to compare both against that.

 

[kpresley84]

Re: Johnson 9.9 still having issues..

thanks rupert...very helpful...but i still havent gotten a clear answer on whether or not my head gasket is leaking??? I have 80# of pressure on both cylinders does that not mean it aint leaking if both are the same?? somebody correct me if im wrong..keep the advice coming!! Thanks!!

 

[rupertmja]

Re: Johnson 9.9 still having issues..

Odds are your gasket is OK. Check everything else first. You have no way to tell if it's leaking until you take it appart though.

 

[kpresley84]

Re: Johnson 9.9 still having issues..

ok, well i'm just going to replace the coils and the water pump and see what that does and i will report back..and if that don't work i will look into the headgasket deal...thanks again!!