75hp Mariner- Starved Carb

[Gvan37]

Got a 1985, 75hp Mariner that is giving me fits. Top carb doesn't seem to want to get fuel. When it does, it runs great. Last four times to the lake ran wonderful. Other day made a couple runs, stopped to fish and it wouldn't go on four cylinders. Only bottom two. Got spark and compression (120lbs) in all cylinders. Figured I'd change the fuel pump diaphragm to eliminate that but didn't help.

I've had the top carb apart twice now and it's clean as a whistle both times. I had the tank out, looking for problems and was using a removable tank for awhile. Ran good with the other tank. The only difference was I changed the tank end fitting to fit the other tank. Rest of the fuel line was the same.

Doesn't help when you pump the bulb when it acts up and will only run on two cylinders. When it stalls after a few tries, it stops and won't be able to start for awhile. Cranks fine, just doesn't seem to get any fuel.

Any suggestions?

 

[Chris1956]

Re: 75hp Mariner- Starved Carb

Recheck the float height, float drop and condition of the inlet needle and seat. Did you change it or is the motor new to you? Sometimes the wrong needle and seat can be installed and mess things up.

 

[Gvan37]

Re: 75hp Mariner- Starved Carb

The inlet needle itself looks great. I didn't look at the inlet seat. What am I looking for? Also, how do I check the float height and drop?

The motor is new to me. Owner said he was having the same problem. I haven't looked at the bottom carb and to see if the two are the same. Probably a good idea. The inlet needle has a shoulder on it where it looks like an arm or something should control it up and down. But, the floats just move another arm that pushes it up from the bottom. Doesn't utilize the shoulder at all. Makes me wonder if it could be the wrong needle.