1992 Yamaha tank size change

[stevesmerc]

I have a 1992 Yamaha that was running fine until I replace the 6 gal. tank with a 18 gal tank. When I did this I connected the fuel direct to the tank leaving the squeeze bulb inline. For the tank vent I used a four inch piece of the gas line. Now the engine will not idle. I have to use the idle adjustment lever to keep the engine running and shift into gear.
Once in gear it runs fine with no cutting out like it is starving for fuel. Although it does seem that the top end has flatten.
Can going to a larger tank affect the gas supply? Being that it was a used tank I flushed the tank and made sure it was clean and put fresh gas in. My first thought is the fuel pump, before I start replacing anything I would like to figure out what the real cause is and fix just than instead of using the process of elimination.

Appreciate any thoughts or input

​Steve

 

[robert graham]

Try draining each carb on to a clean white rag to inspect for water/debris that may have come from new/larger tank....may have a carb jet plugged....

 

[mike_i]

Going to a larger tank should not be a problem as long as you're positive the tank didn't introduce any contamination to the fuel system. What is the condition of the primer bulb when your experiencing problems? Is the any type of inline filter? Is the pickup tube in the new tank clean?