Logo
FULL SITE MENU

1975 Mercury 200 20hp

W

wormsbefamily

New member
Nw to boating and I have as mentioned a 75 Mercury 200 20hp. I have fixed all the wiring and have the motor running. We took it out for a spin. Took time to run it a round just to see how well it would work. When we take it above half throttle it jumps out of gear and the motor revs up. Have a manual for the motor but seen nothing that covers this issue. Thanks
 
I’m having a problem with my 1975 mercury 200 20hp. I have strong spark and a rebuilt carburetor, fuel gets to my carburetor and stays in it and there are no leaks and fuel line bulb gets stiff, I have 120 psi of compression on both cylinders, I have spark but I’m not getting any fuel to my cylinders for it to fire. I tried to spay ether through the intake on the carb and still no fire, then i tried putting fuel in the cylinder by the spark plug hole, put the plugs back in and still no fire and I didn’t put much fuel in the cylinders to flood them out. I have strong spark but no fire. Any suggestions?
 
sounds like you have the basics covered...next item that comes to mind is the timing of the spark - have you checked that?
 
Howw did it run last season?----Does spark jump a gap of 5/16" or more , yes or no ?----Checked flywheel key ?----Tried switching plug wires ?
 
I’m not sure exactly how to check timing. Is there a manual you may know of I can go by and I bought from someone and he showed me a video of it running a few months ago but the throttle linkage was broke so I fixed that and the carburetor. A few weeks ago I could get to fire on full throttle in neutral with full choke and it would only run at high rpm’s not idle but now it doesn’t want to do anything. I’m also not sure how to check the spark gap on the plugs because they are different then what I’m used too, they have flat electrodes
 
The sparkplugs are not used to test maximum spark output from the magneto.-----You buy a $10 test device or make something.
 
This issue could be caused by a few things. It's possible that the shift cable or linkage needs to be adjusted, or that the gears themselves are worn or damaged. It's also possible that there's an issue with the boat's propeller or the alignment of the propeller shaft. To diagnose and fix the issue, I would recommend seeking the help of a qualified marine mechanic who can inspect the boat and motor and make any necessary repairs.
 
Back
Top