81 Mariner 30hp - kills shortly after start

I

iboatlurker

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Sep 22, 2010
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New to the forum.

I have an 81 Mariner (made by Yamaha), 30hp manual start that is giving me fits. I bought the motor used and I don't know its history beyond what I was told.

Some basics:

Good compression (135 psi in both cylinders)
New fuel pump, filter, bulb and lines from carb to tank
New water pump and seals
New plugs
Newly rebuilt carb (rechecked float adjustment and needle)
New gas and oil

I can get the motor to start easily with starting fluid but can't get it to stay running. Seems like it wants to run, but cuts out like it's starved of fuel. The bulb is hard and I can see gas entering the carb venturi after it starts. Any ideas? Thanks!
 
DamianJP

DamianJP

Chief Petty Officer
Joined
Mar 25, 2008
Messages
612
Re: 81 Mariner 30hp - kills shortly after start

Hey iboatlurker

I know it simple but are you running on a pony tank with a vent? Or a big tank?

Starved for fuel eliminates spark stuff and all that new stuff and a recheck of carbs made me thing of something else. You never know.

Lemme know and I'll try to help as much as possible.

DamianJP
 
S

starcraft1982

Petty Officer 1st Class
Joined
Feb 7, 2010
Messages
277
Re: 81 Mariner 30hp - kills shortly after start

NO STARTING FLUID!If anything,spray a little premix.That being said,yes check the vent on the tank.You wouldnt be the first.If that doesnt help,it definately does sound like you have a fuel delivery issue.Recheck all lines and settings on carbs(float levels,idle screw settings,etc.)report back.good luck
 
I

iboatlurker

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Sep 22, 2010
Messages
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Re: 81 Mariner 30hp - kills shortly after start

I know, I know. No starting fluid. I'll switch to premix.

I'm using a six gallon tank at the front of the boat. Fuel lines are long as a result, but I installed new 5/16 line so delivery shouldn't be an issue. I'll check the tank vent - good idea.

I can't check the timing until I get it running...is there a default position I can set to get it going?

Thanks for the replies guys. Appreciated it.
 
M

Mi duckdown

Commander
Joined
Apr 14, 2007
Messages
2,575
Re: 81 Mariner 30hp - kills shortly after start

You don't mention how long that fuel line is. In even though it is 5/16. Not a big fan of drawing fuel more than 6 feet.
 
I

iboatlurker

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Messages
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Re: 81 Mariner 30hp - kills shortly after start

DamianJP said:
Hey iboatlurker

I know it simple but are you running on a pony tank with a vent?

DamianJP
Click to expand...

We have a winner! Went out to the garage and checked the vent...DOH! Runs great. I just built this boat so I had to buy everything new anyway. Glad to get that behind me. Thanks DamianJP!
 
DamianJP

DamianJP

Chief Petty Officer
Joined
Mar 25, 2008
Messages
612
Re: 81 Mariner 30hp - kills shortly after start

Hello iboatlurker

Glad to hear it :D. Cheap and fast fix... Let us know if ya need more help here.


DamianJP
 
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