Under Cowl Fuel Line Diameter

[brentjsimm]

Without me having to buy an owner's manual (I know I need one anyway), can anyone tell me the diameter of the internal fuel lines of a 1991 70hp 2-stroke? In looking to purchase the fuel tubing, I noticed there are fractional, and decimal sizes, that are slightly off...there's a big range. I just want to be sure I'm getting the size the manual calls for. Thanks for any help.

 

[robert graham]

Re: Under Cowl Fuel Line Diameter

Take the tubing to the Yamaha dealer and buy original equipment marine fuel hoses. Could be a couple of different sizes from the cowling to the carbs. Get the correct new hose clamps also. Good Luck!

 

[brentjsimm]

Re: Under Cowl Fuel Line Diameter

thank you, sir, for the reply. under PERFECT conditions, would one assume that all fuel would drain from the internal hoses when not in use? i know perfect conditions don't exist, but just hypothetically speaking.... the lines appear to be in good condition, so i'm not really sure if they need to be replaced or not. should i just run them until failure, or until they show visible deterioration?

 

[robert graham]

Re: Under Cowl Fuel Line Diameter

The Yamaha fuel hoses don't seem to age or deteriorate much, at least on my 1999 they all seem good as new. They're not made of the old automotive type black rubber that used to dry and crack and need replacement so much. Best thing for you might be to forget about the tubing and study up on learning to remove those carb float bowls drain plugs, so you can drain them a couple of times a year, install a fuel/water separator(Walmart/Attwood $27), easy 2 screw installation, get some Stabil and starty using it in your gas, remove/clean your spark plugs, change oil in foot, etc., preventive maintenance items that'll keep your motor running great! Good Luck!

 

[brentjsimm]

Re: Under Cowl Fuel Line Diameter

Thanks a lot for the help and response. As these projects get rolling, I'm sure this won't be the last you'll hear of me.

 

[robert graham]

Re: Under Cowl Fuel Line Diameter

The electronics, fuel hoses, etc. on the Yamaha Motors are mostly trouble free, so you can spend your preventive maintenance time and efforts on providing your motor with clean, fresh, stabilized fuel, clean spark plugs, fresh lower unit oil, healthy water pump impellar. A manual for your motor can make for good reading and save you lots of time and motor troubles. Good Luck!

 

[99yam40]

Re: Under Cowl Fuel Line Diameter

The hoses that Yamaha sells are molded(formed) for the different places on the motor and have their own part numbers and you can find them on the part break down for your model # motor.
also they are metric sized