Carb Trouble mariner 75 ?

A

Ady B

Cadet
Joined
Jan 25, 2009
Messages
8
Hi has anyone got any advice. Ive cleaned and rebuilt the carbs on my engine. It starts ok and runs well when given revs but I cant get it to idle. When I adjust the low speed mixture it doesnt seem to make any difference. The test tank has got a film of black oil on the surface now, could the oil pump be pumping to much oil? Its set so the marks line up at idle. Any help.
Thanks Ady B
 
L

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: Carb Trouble mariner 75 ?

It sounds like a float related problem, possibilitys are float height or a inlet leaking. There is also a chance of a ruptured fuel pump diaphram.
 
A

Ady B

Cadet
Joined
Jan 25, 2009
Messages
8
Re: Carb Trouble mariner 75 ?

Thanks Laddies, I'll check fuel pump to see if problem is there. I have checked and reset float levels to 7/16" and replaced inlet needles as part of rebuild. Thanks again Ady B.
 
A

Ady B

Cadet
Joined
Jan 25, 2009
Messages
8
Re: Carb Trouble mariner 75 ?

Cheers Laddies, it was the fuel pump, tear in the diaphragm, thanks again
Ady B
 
J

jmburock

Petty Officer 2nd Class
Joined
Aug 25, 2005
Messages
174
Re: Carb Trouble mariner 75 ?

Don't lose those little plastic discs that come with the fuel diaphragm kit. The pieces have a way of getting lost. I always buy 2 of these kits when I know I'll be using one. These fuel pump diaphragms seem to go bad often, perhaps more often now in the days of ethanol-blended fuel. Plastic and 10% ethanol probably don't mix.
 
Barnacle_Bill

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: Carb Trouble mariner 75 ?

Those discs are the new style check valves. They replace the old rubber ones as ethanol causes the edges to curl up. Merc has a TSB out on it.
 
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