No power from my 1965 75 hp sea horse

M

mgolding

Recruit
Joined
Jun 20, 2011
Messages
4
PLEASE HELP!!!!!!! I have 1965 Johnson 75 hp Sea Horse outboard (V4AL-17S). My top speed is 10mph. I have drained nad put new gas in the tank, I have changed the plugs, checked the reed values, rebuilt the carb, cleaned and verified the gap on the points, checked to ensure fuel and spark were at each cylinder, compression tested each cylinder - all cylinders read the same (90 psi), and replaced the inline fuel filter in the fuel pump. However, when the engine is idling it runs fine - when we pull the plug wire from each cylinder the no 1 and 2 cylinders have no noticeable difference in how the engine runs but when we pull the plug wires from cylinders no 3 and 4 there is a major difference. We are at our wits end ..... we are leaning towards new points cap, etc .... any ideas --------PLEASE HELP --------
 
M

Monte1961

Lieutenant Junior Grade
Joined
May 8, 2011
Messages
1,180
Re: No power from my 1965 75 hp sea horse

Are 1 and 2 on the same coil? You are on the right track. Check point/s check coil/s and condensers. chime in if you need any more help and welcome to iboats.
 
F

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: No power from my 1965 75 hp sea horse

mgolding said:
PLEASE HELP!!!!!!! I have 1965 Johnson 75 hp Sea Horse outboard (V4AL-17S). My top speed is 10mph. I have drained nad put new gas in the tank, I have changed the plugs, checked the reed values, rebuilt the carb, cleaned and verified the gap on the points, checked to ensure fuel and spark were at each cylinder, compression tested each cylinder - all cylinders read the same (90 psi), and replaced the inline fuel filter in the fuel pump. However, when the engine is idling it runs fine - when we pull the plug wire from each cylinder the no 1 and 2 cylinders have no noticeable difference in how the engine runs but when we pull the plug wires from cylinders no 3 and 4 there is a major difference. We are at our wits end ..... we are leaning towards new points cap, etc .... any ideas --------PLEASE HELP --------
Click to expand...

That's a bit odd. One set of points fires #1 & #3, the other fires #2 & #4. Likewise for the two carburetor barrels. Are you counting the cylinders from the top, zig-zagging from side to side? (You should)

The only other thing I can think of is the plug wires may be mixed up on the two non-firing cylinders. Firing order is 1-2-3-4.
 
M

Monte1961

Lieutenant Junior Grade
Joined
May 8, 2011
Messages
1,180
Re: No power from my 1965 75 hp sea horse

This is going to be interesting!
 
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