77 Johnson Re-Diagnostic

Mnemonic

Petty Officer 1st Class
Joined
Nov 3, 2004
Messages
285
OK, i just pulled my boat from my slip. Pulled off the '77 70HP johnson and put it on the testing mount.<br /><br />The previous problems when on the boat was it was stalling after you put the throttle up in gear, one of the cylinders werent firing, and the spark plug threads were stripped on #2.<br /><br />So here's what i have discovered so far:<br /><br />#1 - the little linkage that moves something near the stator wasnt attached to the throttle bar. the little plastic grommit that holds that linkage is broken - anyone know the part # for this and where to get it? What problem could this cause?<br /><br />#2 - I replaced the coil on #3, and i am getting a intermittent spark, could be because of a loose plug cable though, I will test that part tomorrow. - Also, #1 and #2 get a decent spark..<br /><br />#3 - I am using a Heli-Coil on #2 to rethread the head.<br /><br />I tested the compression, all cylinders are 125psi, (Even without threads on #2, i just held it really hard on the hole)<br /><br />I rebuilt the carbs when the motor was on the boat, so that is ruled out...<br /><br />Any ideas?
 

REELSPORT

Petty Officer 1st Class
Joined
Apr 14, 2005
Messages
235
Re: 77 Johnson Re-Diagnostic

that little linkage is your timing advance and you might be able to find one at a boat salvage yard. good luck
 

Mnemonic

Petty Officer 1st Class
Joined
Nov 3, 2004
Messages
285
Re: 77 Johnson Re-Diagnostic

Do you think if that wasnt moving when the throttle advanced it would cause this problem?<br /><br />Also, after i re-connected it with tape as a temporary solution the motor wouldnt fire, and it sounded like it was sneezing. Any idea what this would be?
 

DHPMARINE

Captain
Joined
Dec 16, 2003
Messages
3,688
Re: 77 Johnson Re-Diagnostic

Your broken part is #395448.Buy it from your nearest Bombadier Dealer.I'm in MA. Grin.<br /><br />This piece syncronizes the carbs with the timing.<br />Even one turn out on any adjustment throws this sync way off.<br /><br />Start with this part,but you may have more problems.<br /><br />DHP
 

Mnemonic

Petty Officer 1st Class
Joined
Nov 3, 2004
Messages
285
Re: 77 Johnson Re-Diagnostic

DHP - I appreciate the help... I will pick up this part tomorrow. <br /><br />I was afraid timing was going to come in to this, because i have NO idea what all these tems like 4*, BTC, etc mean and have no idea how to do timing, and also dont want to buy a timing light.<br /><br />Any idea if this peice could be causing the sneezing problem? Could the sneezing be pre-ignition? I heard that is REALLY bad for the piston.
 
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