1979 70 hp Johnson - hard starting

oski26

Cadet
Joined
Sep 20, 2008
Messages
9
Help - we have a 1979 Johnson 70 hp outboard motor that we have issues restarting. We have good compression - new plugs - coil packs and power pack. The fuel pump was rebuilt. When the motor is cold it starts up great and runs smooth, but if we stop to fish or anything and try to restart - we can't get it started. The carbs are clean and have new needle seats installed. Today we started it up on muffs and had the prop in a barrel of water. When we stopped the motor it restarted a few times but then we had the samething happen - would not start. I drained the carbs and tried it again - it started just fine. Then I disconnected the gas line and stopped the motor - reconnected it and restarted with no issues multiple times. I feel the carbs are flooding on low idle - but not sure how to correct. I was told that it sounds like its running to rich and needs the carbs adjusted. I checked the floats and they are adjusted level to the bowl and has 3/4 inch travel - what I found online. Can anyone help point me in the right direction before I take it to the marina for repair.
 

MAW31

Petty Officer 1st Class
Joined
Aug 15, 2009
Messages
217
Re: 1979 70 hp Johnson - hard starting

when you say 'cant get it started'.
how does it act?
do you use the choke?
does is sputter and die?
does it just crank?
what makes you think the 'carbs are flooding' ? does it smoke excessively?
 

petryshyn

Commander
Joined
Oct 3, 2001
Messages
2,851
Re: 1979 70 hp Johnson - hard starting

Have you checked for spark when it won't start?
 

Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: 1979 70 hp Johnson - hard starting

Couple of thoughts, don't use muffs and put the lower unit in a barrel, one or the other. When engine will not start, if you use the choke does it help? You said you drained the carbs and it started, did you pump the primer to refill the carbs with fuel? You do not have any adjustments on your carbs, jets are fixed. Have you checked for spark when it will not start? Duplicate no start and try squrting some fuel mixture into carbs and see what happens.
 

oski26

Cadet
Joined
Sep 20, 2008
Messages
9
Re: 1979 70 hp Johnson - hard starting

Sorry - when it won't restart - it just cranks - I tried with and without chock and move the throttle up to full - just cranks. Getting great spark, but it all seems to be fuel issue. After it won't start - I drained the carbs and tried to start again and it started after 5 seconds of cranking.
 

MAW31

Petty Officer 1st Class
Joined
Aug 15, 2009
Messages
217
Re: 1979 70 hp Johnson - hard starting

what check were you doing to know it was getting 'great spark' at that time?
 

oski26

Cadet
Joined
Sep 20, 2008
Messages
9
Re: 1979 70 hp Johnson - hard starting

I have in-line spark plug testers as well as pulling each plug and checking.
 

Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: 1979 70 hp Johnson - hard starting

It only takes 3 things to make it run, spark, compression, and fuel. Thinking your compression is OK because when it runs, it runs OK, spark because you said it was Ok, only leaves fuel.
 

oski26

Cadet
Joined
Sep 20, 2008
Messages
9
Re: 1979 70 hp Johnson - hard starting

Yes - I know its the fuel system. Carbs are flooding, replaced float valve seat assy. and rebuilt fuel pump, but still the same results. Can anyone help with any adjustments?
 
Top