Does it matter? I just replaced my 35hp's old, hard as a rock fuel line (5/16 dia.) with a new one that has a 3/8 dia, and the motor won't stay running. It's probably just the float/needle but I just want to make sure.
Napa sells the correct size hose for cheap. I doubt you will be able to get a good seal with 3/8 inch fuel line. Even with clamps you are more prone to air leaks and gas leaks with the larger diameter hose. Six feet should be enough to do all the hoses and the cost is probably a buck a foot. While you are there get a carb kit for it and fuel pump kit. If your hoses are that hard the rubber in the pump and carb are in the same condition. Rebuilds are easy. Part numbers are 18-7806 for the fuel pump and the carb is 18-7037. Pump rebuild kit is 10 bucks and the carb kit is 15 bucks
I wouldn't expect much difference, but if your fuel pump is operating marginally, it might not be able to pull the additional weight of the gas contained in the larger hose. I mean it's not like it's much weight. But if your pump was barely able to draw with the 5/16, it might not be strong enough to pull it thru a 3/8. That's about the only thing I can come up with.
Is the Fuel line for the 85 Force motor the same 5/16"? I want to re do all the fuel line in my motor.<br />I dont car eif the 3/8" is bigger I just want it to be correct.<br /><br />Also note I did a search.
Excellent Guys! You've been a big help! It was warmer today, so I installed the fuel pump kit, carb kit,& new fuel line. After a little carb adjustment, she fired right up and stayed running until I shut it down <br />The old diaphram was toast, very brittle and cracked, and now I don't have to keep pumping the primer bulb to keep fuel flowing!.... I know it's the little things in life.... Thanks again!
<br />The old diaphram was toast, very brittle and cracked, and now I don't have to keep pumping the primer bulb to keep fuel flowing!.... I know it's the little things in life.... 
