Need Help With 1985 Merc 7.5 Hp

[kansasbassfisher08]

I bought this motor 2 years ago sat in a guys shop it was nice and shinny. so i bought it. took it home change the plugs got a new fuel cell and hoses and gas. after a couple pulls started right up im thinking great took it out it was hard to start but finally started. next trip i used my minnkota went all around a lake started getting low on charge so i went to fire up the motor no go no start. got home changed the plugs and no go asked a guy and he said fuel problem so i took the carb off cleaned every thing but tore the gasket going between the block and the carb i thought it will be fine. i cleaned all the parts and whiped off the gaskets in the diaphram. cleaed the screen where the fuel enters the diaphram. i sprayed it with starting fluid and got it to go for a couple seconds til the started fluid ran out i guess but thats really it can this be cus the diaphram gasket or something. i took the cap off the fuel cell cus i thought it was a vent i even ran the line directly in the tank. need help please help

[fishinwrench]

Hi, and welcome to "Itty Bitty Merc Fuel System 101/Carb"

3 things....

If it is a Walbro carb (stamped WMB) then the fuel pump is operated by vacuum through a port at the carb flange, so a torn gasket is not acceptable, and gasket position is important.....see the little hole in it?

When you put the carb back together what setting did you end up with on the idle jet (needle valve) ?

Initial setting (before fine tuning) should be 1 1/2 turns out from lightly seated.

Regardless of whether it has the Tillotsen or Walbro carb there is a service update on the inlet needle valve (the newly recommended one has no spring on it and float level is set "level with the flange while holding the carb body upside down").

Good luck.....and isn't that starboard side flange nut a PIA to get on/off? I use a 7/16 snap-on combo wrench and a "kabob skewer" (also known as Itty-Bitty Merc Special tool # 762)

Not to add extra pressure to you or anything....but if you drop that nut you're phucked. LOL

[kansasbassfisher08]

Hi, and welcome to "Itty Bitty Merc Fuel System 101/Carb"

3 things....

If it is a Walbro carb (stamped WMB) then the fuel pump is operated by vacuum through a port at the carb flange, so a torn gasket is not acceptable, and gasket position is important.....see the little hole in it?

When you put the carb back together what setting did you end up with on the idle jet (needle valve) ?

Initial setting (before fine tuning) should be 1 1/2 turns out from lightly seated.

Regardless of whether it has the Tillotsen or Walbro carb there is a service update on the inlet needle valve (the newly recommended one has no spring on it and float level is set "level with the flange while holding the carb body upside down").

Good luck.....and isn't that starboard side flange nut a PIA to get on/off? I use a 7/16 snap-on combo wrench and a "kabob skewer" (also known as Itty-Bitty Merc Special tool # 762)

Not to add extra pressure to you or anything....but if you drop that nut you're phucked. LOL

lol thanks for your help im waiting on a diaphram gasket kit right now and i also got the flange gasket too and im not sure how to set the inlet needle valve but im going to try and not sure to know if the floats touching the right spot wish i could talk on the phone a PM would be nice lol but if not thats cool too thanks again will know in about 7 days when i get the parts

[fishinwrench]

573-569-5406

[jackalope]

I may have missed this but did the bowl have fuel in it? IF SO....I would recommend tearing the carb down and dipping it for a few hours. A new needle, seat, gaskets, and float can be had for about $20. Thats worked for me about 90% of the time ive had fuel issues.