1975 6 hp Johnson Compression trouble??

[Pinecreek1]

Hi, I just recently got my hands on a 1975 6 hp Johnson (6r 75r). The guy told me it had been in a garage for 10 years. My first attempt at starting it was unsuccessful and i determined i had no spark in the top plug. I changed the points, condensers and set them to .020 also got new plugs and have spark at both. I squirted a lil fuel mixture in the carb and pulled and pulled and that didnt help until about the 50th pull and then it would run for about 3 second and die. I have done this several times over the past couple days to the same conclusion. I have read in other posts about getting a good 1/4" to 3/8 arc from your plug when testing it wheras mine will spark fine it seems but only when i ground the plug to the block. I cant get it to jump from the plug to the block. Could the coils and wires be my problem? I have tested the compression of both cylinders and the lower cylinder is at 60 psi and the top is at 75 psi. I understand this is low compression but it baffles me that it can start and run for a few seconds here and there. Is the compression difference something that would cause this behaviour? All comments appreciated , thanks, Syd.

 

[xjdriver]

Re: 1975 6 hp Johnson Compression trouble??

It should run with that compression, sound like you have a fuel delivery issue. Make sure gas is getting to carb, if so then clean the carb, and make sure float and needle valve move freely. The spark plugs will not spark unless grounded, you need a spark tester.

 

[Pinecreek1]

Re: 1975 6 hp Johnson Compression trouble??

Hi, yeah i will get a spark tester tomorrow to see if i have enough juice. Could that explain why it takes so many pulls to start after spraying fuel in carb? Thanks Syd

 

[boobie]

Re: 1975 6 hp Johnson Compression trouble??

First thing to do is get the open air gap spark tester set at 1/4" and then check your spark. Go from there.

 

[Rick.]

Re: 1975 6 hp Johnson Compression trouble??

I agree with Boobie. I would also add I'd be dying to pull the flywheel and clean house under it.... anything that needs it. clean points and gap check them. Then check for spark because from what you said it already sounds weak at best.

 

[xjdriver]

Re: 1975 6 hp Johnson Compression trouble??

Ya, check spark, but im just wondering if you had a fuel line connected or were you just spraying pre-mix in the carb?

 

[Pinecreek1]

Re: 1975 6 hp Johnson Compression trouble??

Ya, check spark, but im just wondering if you had a fuel line connected or were you just spraying pre-mix in the carb?

Hey thanks for the responses. We had an ice storm(freezing rain) and knocked our power out for 3 days so i havnt had internet access to reply. Any how , I did have the fuel line connected and was spraying pre mix in the carb. I bought a spark tester at our local napa and i couldnt get spark on either cylinder. Its a non adjustable type spark tester with what looks like a 1/4 gap. The coils i pulled off looked fine other than the probe that connects to the plug wire was rusty on both and the wires felt hard and cooked. So i put 2 new coils and plug wires on and i still get a fail on the spark test. (the plugs spark when i test that way). I ran out of light and will have to wait until morning to try to start it but I was hoping it would have passed the spark test....

 

[Pinecreek1]

Re: 1975 6 hp Johnson Compression trouble??

Hey thanks for the responses. We had an ice storm(freezing rain) and knocked our power out for 3 days so i havnt had internet access to reply. Any how , I did have the fuel line connected and was spraying pre mix in the carb. I bought a spark tester at our local napa and i couldnt get spark on either cylinder. Its a non adjustable type spark tester with what looks like a 1/4 gap. The coils i pulled off looked fine other than the probe that connects to the plug wire was rusty on both and the wires felt hard and cooked. So i put 2 new coils and plug wires on and i still get a fail on the spark test. (the plugs spark when i test that way). I ran out of light and will have to wait until morning to try to start it but I was hoping it would have passed the spark test....

Also, i noticed when putting the new coils on that they looked like they could be adjusted a little bit in and out. I know you dont want them rubbing the flywheel but how close is enough and if you can adjust them how can you tell how close it is? Thanks, Syd

 

[Pinecreek1]

Re: 1975 6 hp Johnson Compression trouble??

Also, i noticed when putting the new coils on that they looked like they could be adjusted a little bit in and out. I know you dont want them rubbing the flywheel but how close is enough and if you can adjust them how can you tell how close it is? Thanks, Syd

I forgot to mention that I did pull the carb apart and freed up the needle valve and give it all a quick clean. I still need to get a carb kit for it for sure

 

[Rick.]

Re: 1975 6 hp Johnson Compression trouble??

http://forums.iboats.com/engine-fre...-change-coils-set-points-old-omcs-294072.html
Clean and gap your points and I always clean the inside of the flywheel real good to. Especially the magnets. Rick.

 

[boobie]

Re: 1975 6 hp Johnson Compression trouble??

Did you put new condensors in it ??

 

[iwaterdave]

Re: 1975 6 hp Johnson Compression trouble??

If you freed up the needle valve did you put it back in the same as you took it out? If its the needle valve I think it is it would be the air/fuel mixture valve. I always turn it all the way in but back out 2 complete turns.

 

[Pinecreek1]

Re: 1975 6 hp Johnson Compression trouble??

If you freed up the needle valve did you put it back in the same as you took it out? If its the needle valve I think it is it would be the air/fuel mixture valve. I always turn it all the way in but back out 2 complete turns.

The fuel air mixture valve is set at 1.5 turns out. Yep new condensors, points, coils , wires and plugs. Points set at .020. The needle valve I mentioned i had cleaned is the one in the carb riding the float. What am i missing, why cant i get a pass on the spark test? I will try to start it after i get the kids off to daycare

 

[Rick.]

Re: 1975 6 hp Johnson Compression trouble??

All new electrics and no spark. That is unusual. You may want to try lulling the recoil in the dark of night. Spark will show up better in the dark. Did you set your coils straight in line with the magneto bosses? I'm a little stumped but will be thinking about it. Does your engine have a kill switch/button? If it does, disconnect it and check for spark. Leave it disconnected until you get this spark thing resolved. Rick.

 

[jbjennings]

Re: 1975 6 hp Johnson Compression trouble??

60psi on one and 75psi on the other is horrible. Before you spend too much on it..... figure out the compression thing. I agree it should run if even on one cylinder and bad spark or a stuck float needle is usually all that will prevent it. I'd cut the plug wires back about 1/2 on either end and re-install them on the plug boot and coil. The wires should thread onto the coil.
Good luck---I hope it's a stuck ring or bad head gasket causing your low psi.
JBJ

 

[nwcove]

Re: 1975 6 hp Johnson Compression trouble??

The fuel air mixture valve is set at 1.5 turns out. Yep new condensors, points, coils , wires and plugs. Points set at .020. The needle valve I mentioned i had cleaned is the one in the carb riding the float. What am i missing, why cant i get a pass on the spark test? I will try to start it after i get the kids off to daycare

have you tried spraying premix directly into the carb, or putting a few drops in each plug hole?
( verify your spark tester, the ones ive seen that are non adjustable are usually 7/16 gap, big difference from 1/4 to 7/16 when you're dealing with a universal mag) jmo