1987 25HP Mercury Won't Start

[qtiznip]

Hello All

I have a late 80's 25hp mercury 2stroke that I can't get to start. The last time I was able to get it start was last year. I started up great ran for most of the day.

When I was headed to the dock I was going and then it just kind of died it. Seemed like it wasn't getting gas or something. I got it to start again, made it half a mile and then it died about 100 yards from the dock.

I have not been able to get it started since.

I have tried starting it in the yard with the hose hooked up to it but no go.

I had it serviced at the beginning of last year. Tech said it was in great shape internally- high compression and all.

Do any of you have an idea what it could be or a list of where to start looking?

Any help you can give would be appreciated.

Thanks ahead of time for any help.

 

[ONERCBOATER]

Re: 1987 25HP Mercury Won't Start

does it have spark?
if it has spark.... get a spray bottle and squirt some 50:1 fuel into carb(s) and see if that gets it to fire. if so then carb/fuel problem. if not we will have to look harder.

 

[qtiznip]

Re: 1987 25HP Mercury Won't Start

does it have spark?
if it has spark.... get a spray bottle and squirt some 50:1 fuel into carb(s) and see if that gets it to fire. if so then carb/fuel problem. if not we will have to look harder.

Thanks for the reply. It does have spark. I'll give this a shot though and post what happens.

In the meantime if people have any other ideas they are really appreciated.

 

[ONERCBOATER]

Re: 1987 25HP Mercury Won't Start

if that works... likely culprit is dirty carb... will need disassembly and cleaning..... if it started on own and died out i would say fuel pump instead.... 2:1 it is carb.

 

[qtiznip]

Re: 1987 25HP Mercury Won't Start

if that works... likely culprit is dirty carb... will need disassembly and cleaning..... if it started on own and died out i would say fuel pump instead.... 2:1 it is carb.

Thanks for the advice thus far. I sprayed some 50:1 fuel in there and it started easily an ran for a few seconds. Would this suggest a bad fuel pump?

 

[prayferrell]

Re: 1987 25HP Mercury Won't Start

No. As said above it is more than likely the carb. I bet you don't even have to disassemble it all the way. Just take it off and hit all your holes with carb cleaner and you should see improvement. If you rebuild the carb and still have trouble then you can go to the fuel filter for issues. No gas can get to your filter if it cant pass the carb. I am no expert but I have learned this. Had the same problem with my 25 Johnson, carb clean does wonders.

 

[qtiznip]

Re: 1987 25HP Mercury Won't Start

So to what extent do I need to take the carburetor apart to clean it? If i am taking it apart I'm guessing that I will have to remove it and replace all the gaskets when I put it back on. Is this correct?

 

[qtiznip]

Re: 1987 25HP Mercury Won't Start

Hello all,

Took the carburetor apart. A very small amount of discoloration on some of the metal which I'm assuming to be varnish from fuel. Beside that everything seemed very clean. The only thing that looked questionable was the fuel pump diaphragm and gasket.

I've ordered a carburetor rebuild kit and am going to rebuild it. Probably could have replaced just the diaphragm and gaskets but found a full kit for only $15 more so figured would replace everything for piece of mind sake.

I am going to pull the rest of the fuel line apart and try to flush it. Is gas the best thing to flush with? Anything else that might do a better job yet not mess up the engine if there is still a small amount in there when everything gets put back together?

If you have any other ideas they would be appreciated.