Mercury 7.5

Hey guys, I bought a Mercury 7.5 Hp outboard motor from a friend a couple months ago and replaced the seals in the carburetor as well as cleaned it, replaced the fuel lines, and put a new spark plug in it. But its still giving me troubles. I'm thinking it may need a new fuel pump (I really don't know how to diagnose engine trouble though). Its very difficult to start, won't idle, and when i turn the throttle all the way up it will cut out every few seconds like I'm turning the trottle up and down. So if anyone has other ideas as to what it could be that would be great! also what kind of fuel pump should i get? the serial number is 2634501

Re: Mercury 7.5

My suggestion in order are:

Get yourself a factory service manual if you can, a Seloc at least (I used a Seloc and it was OK, but the factory manual is better).

Check compression if you haven't already.

Check all fuel lines all the way to the tank pick up, or use a known good tank. Clean/replace as necessary.

Put in a fuel pump rebuild kit - cheap and easy.

If you didn't actually totally dismantle the carb and soak/clean it and pretty much put a rebuild kit in it, do that.

Check spark to make sure your stator, coils, switch box, etc are up to snuff. Don't just check for spark, check the strength with a spark gap tester. Replace parts as necessary. I'm not sure of the year of your engine and what ignition parts it has, but with my older merc, the coils and/or switchbox can certainly make it run poor, sometimes intermittently.

Oldmercs.com is a good source for parts. That site should get you an idea of the year too.