fuel line I.D question

[crabmanjv]

I have a 185hp (305) omc 800 and I'm installing new fuel lines. My existing line from inlet valve to fuel/water seperater is 5/16 ID and existing line from seperater to fuel pump is 3/8 ID and from fuel pump to carb is 5/16 ID. My question is will there be any forseeable problems installing all 5/16 ID lines? thanks

 

[JoLin]

Re: fuel line I.D question

What size are the FITTINGS? Are they in fact 2 different sizes, or are you asking if you can repeat the same mistake the last guy made?

Physically, you can likely force the 5/16 hose over the 3/8 nipple, but it might someday split when the hose gets older and loses resiliency, as they all do.

Half-assed repairs eventually prove to be just that. You don't need that drama, especially on the water, and especially when you're dealing with something as volatile as gasoline.

 

[crabmanjv]

Re: fuel line I.D question

Fittings all match the hoses. I guess the main question is there a need for 3/8 hose from filter to fuel pump? I will change everything just to do it right. Just need to know if 5/16 throughout is acceptable or do I need to use 3/8.thanks

 

[Don S]

Re: fuel line I.D question

3/8" fuel line is recommended on all I/O engines in todays world, not sure what they recommended 30 years ago. The reason is less restriction. All the fittings are smaller than the inside of the hose. So the smaller the fitting, the less fuel can pass thru it, and the more fittings are the less fuel finally makes it to the fuel pump and carb.

 

[crabmanjv]

Re: fuel line I.D question

Thanks for the replies. I assume that since my line from pump to carb is 5/16 and the pump can only take as much fuel from the filter as needed, a 5/16 line would be suffecient to supply or fill the filter and therefore 5/16 line could be used from filter to pump. Say that 10 times fast! thanks

 

[chiefalen]

Re: fuel line I.D question

From the fuel pump to the carb is metal?

 

[Don S]

Re: fuel line I.D question

From the pump to the carb is a pressureized line, from the tank to the fuel pump is suction/vacuum. So don't mix apples and oranges.
Use 5/16" if you want, but don't complain here that your engine had a meltdown from running lean because of a small fuel line on the suction side.

 

[crabmanjv]

Re: fuel line I.D question

Thanks thats what I needed to here! 3/8 it is. And cheifalan yes It was a metal line but it was cracked and from what I understand its uscg approved to use a A1 rated fuel line from pump to carb. Please correct me if I'm wrong.

 

[Don S]

Re: fuel line I.D question

It is ok to use type A1 hose, but you can't just cut the steel line off and put a hose on it. You need to have the proper type hose barb fittings in the fuel pump and carb.