'77 85hp Mecury Outboard--Won't start--does turn over

danbedman

Recruit
Joined
May 25, 2003
Messages
1
I have a '77 85hp Mercury outboard with a Thunderbolt ignition. It is 4 cylinders. When I try to start it, it sounds like it is turning over fine, but it just won't start. I have tried different batteries and have replaced the sparkplugs. Anyone have any suggestions? I don't have an owner's manual for the motor as I bought the boat used.<br /><br />Thanks.
 

Solittle

Fleet Admiral
Joined
Apr 28, 2002
Messages
7,518
Re: '77 85hp Mecury Outboard--Won't start--does turn over

Welcome Dan - Get a shop manual and follow the troubleshooting procedures. You need to find out if you are getting spark and good fuel. Plan on checking compression, repace the water pump, gear oil, etc. Come back here when you get stuck.
 

BF

Lieutenant
Joined
Apr 8, 2003
Messages
1,489
Re: '77 85hp Mecury Outboard--Won't start--does turn over

Hi Dan,<br /><br />A couple of things... you're new to this boat & motor, but I don't know if you're new to outboards in general. So, first you know that you need to either have water "muffs" on the water inlet, or the lower unit submerged in water right when you start it, right? Otherwise, your water impeller will be destroyed very quickly. Second you know that you need oil mixed in the gas, right? (50:1)<br /><br />Now for starting... I'm guessing the motor turns but doesn't start? You have pumped the fuel line primer bulb until it is firm? You have lifted the fast idle lever all the way up? You turn the motor while holding the choke button (either a separate button, or sometimes is done by pushing the key in). You should hear a click from the motor when you push the choke button. Last thing, is that my merc doesn't like to start if it's tilted up (it never gets enough fuel)... mine needs to be pretty much level to get fired up, and then can be tilted up after that. I'd make sure the choke works, if that's OK, I'd look for spark and then look at cleaning fuel filter/screen etc.<br /><br />As has been suggested, a manual would be a good investment. Also, you might consider changing the lower unit gear oil unless you know it's been done lately (that should be done yearly).<br /><br />Good luck, and let us know when you need more help or if you get it going (and what you think the problem was).<br /><br />Brent
 

MercMark

Petty Officer 2nd Class
Joined
May 20, 2003
Messages
149
Re: '77 85hp Mecury Outboard--Won't start--does turn over

It sounds like we have close to the same engine. I'll try and remember your name. I'm about to start in on a powerhead rebuild on my late 70's 85hp merc with thunderbolt ignition.<br /><br />I've got a manual that covers your engine (even if they're a coupld of years separated). I'll tell you the publisher etc...I can even tell you the ISBN number. I'll post when I get home. It's a good manual, and I expect to be reading it through a few times before I tear into my engine.
 
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