1981 7.5 merc killing me

[nickb911]

I'm at my wits end. Carb is clean, plugs are new, tank and fittings clean and new. Ran perfectly last year. This year...

Trying to start: Choke and pull, release choke and pull, fuel pours from front of carb. Replaced needle, float looks good. Sometimes starts, usually not.
When running, water comes from tell-tale hole semi-intermittently at neutral idle, but fine at speed. Doesn't seem too hot. When it did run it would die when shifted into gear or bog down at WOT and die. Last time out I thought it was working fine. Took me almost 2 hours to get home with the electric motor.

When I cleaned the carb I replaced all but the gasket around the screen on the side where fuel comes in, (it wouldn't fit and fuel kept leaking from that connection.)

Manual said it's possibly the reed? Not familiar with that part. Could it be the fuel pump? I don't know where the fuel pump would even be on this motor. I've spent more hours than I care to admit to working on this thing in the driveway and it seems I'm still at square one. It must be something simple since it ran fine before.
I'm considering paddling my boat out into the lake and using this motor as a very expensive anchor!
Thanks in advance for any help I can get.

 

[Myke48]

Re: 1981 7.5 merc killing me

If you have gas coming out of the carb you need to rebuild the carb and use new gaskets.
I had the same problem with bogging and gas coming out of the carb.
I tried all sorts of fixes new fuel pump,even took the carbs off and cleaned them.
Not untill I got a rebuild kit and did it the right way did it work like a dream.
If you want to have a trouble free day on the water do it right,,no quick fixes to rebuilding the carb.
You have to also adjust the floats when you install new ones,,and yes you need to install new ones,they come with the kit.
Hope this helped,,Mike

 

[lowkee]

Re: 1981 7.5 merc killing me

Although Myke is correct that doing an all out rebuild is the way to go, your issue sounds like the needle is not seating well or the float is flooded (assuming a hollow float). Either way a carb removal is needed.

Remove the float, shake it next to you ear. If it makes noise, replace it as it's flooded and floats as well as your boat full of water, hense the carb flooding. If it remains quiet, remove the needle, blow some compressed aire into the seat (what the needle sits into), then carefully rub the rubber tip of the needle with your fingers. The needle and seat need to be PERFECTLY clean when you put it back together. One tiny particle and your fuel pump will load up that carb.. well, as much as it is now

Put carb back together. Test. If tests okay, run for another year, but order up a rebuild kit for next time the carb is off.

 

[nickb911]

Re: 1981 7.5 merc killing me

The float is old and crusty-lookin'. I'll replace that for good measure. I actually replaced the needle which is all metal and just sits in a hole in the Brass? seat. I cleaned the "seat-hole" with spray-carb-cleaner, polished the new needle with a clean rag and blew canned air through before inserting it. Maybe that's my problem there as well. If it's supposed to have rubber on it, it surely doesn't right now. That's the way they said it should be when I bought the part at the shop. Hmmm...maybe I got hosed.
BTW, would fuel gush out while priming if the float wasn't floating?

 

[lowkee]

Re: 1981 7.5 merc killing me

If you prime it enough, yes, fuel will come out of the carb if the float is flooded or if the needle isn't seaing correctly. An all metal needle isn't that rare, as it just means the seat has a rubber oring int it. There is always a rubber seal, it just varies which part has it. You may want to check and make sure the seat didn't lose the oring while getting cleaned. That would definitely cause flooding.

 

[nickb911]

Re: 1981 7.5 merc killing me

Put a nice, new plastic float in today. Fired right up! Thanks! I ran it at home for twenty minutes or so. But, when I got to the lake 30 minutes later, it didn't want to start. I choked and played with the choke and eventually it started. Still not right it seems. Died once at WOT and doesn't seem to be running perfectly even (surging), as it did before. I have two theories:

1. Rain may have gotten in the gas tank.
2. Plugs may not be gaped properly.

Any thoughts?