Stainless Steel Fuel Hose

Quarterwave

Petty Officer 2nd Class
Joined
Sep 16, 2013
Messages
118
Hi everyone,

After taking a brief break from building my engine, I'm back at it and need to make some new stainless steel fuel lines for my 5.7 Mercruiser. The engine is a truck engine that I am in the process of converting into a boat engine and part of that change was needing an electric fuel pump (no provision for a mechanical pump on this block).

As a result, the stainless steel fuel hoses that run from the pump to the water/fuel separator and then from the separator to the carburetor no longer fit - and so, I need to make some new ones.

I believe the outside diameter is 3/8" - but maybe I'm wrong?

Also - what size/type connectors will I need or should I just re-use the ones I have?

Where is a place to source the tubing?

Lastly, I'll be learning how to roll the lip on the tubing as well, as I have the tool for that.

Any help is appreciated.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,306
its not stainless steel tubing, its simply plated steel tubing with paint on the outside

the ends are inverted flare. the 3/8 tube nut is a 5/8-18 inverted flair. Inverted flare is the automotive connection of choice

this is the same tubing used as brake line - available at any napa.

its a double flare tool (I have 4 of them) make sure you buy a good tool. I have 4 because 2 are lower cost junk that I cant return. buy an extra length of tubing, it takes practice to do a double flare. you also need to do a bevel on the outside of the tubing for the flare to work properly

you do not need steel line, you do need coast guard approved line which also includes A1 and A2 hose. uscg approved 3/8" A1 fuel hose is what I would use from your electric fuel pump to the carb. A2 is used on the fill side of the tank and is the minimum that you need on the pump inlet. (I use A1)

you did wire a relay and oil pressure switch to control your fuel pump, correct?

or you could simply drill the 4 mounting holes and drill thru the block web to mount a mechanical pump. the boss is still there, its simply not machined.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,468
that run from the pump to the water/fuel separator and then from the separator to the carburetor

Ayuh,.... For the most part,... What Scott said,..^^

I'll add, that the routin' is, fuel Filter 1st, then the fuel Pump, then the carb,....
No reason to run any nasties through the fuel pump,....
 

Rick Stephens

Admiral
Joined
Aug 13, 2013
Messages
6,118
It is very likely you can also just purchase the Mercruiser fuel line from pump to carburetor - I did. And they are nice. Have to have nearly the same setup as one of the years from Merc, but then everything fits perfectly.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,306
and pre-fill the filter with fuel when you screw it in. helps the pump prime faster.

if you need help on setting up the oil pressure switch, just ask.
 

Quarterwave

Petty Officer 2nd Class
Joined
Sep 16, 2013
Messages
118
Thanks everyone. I'll look into picking up the line and get some extra length so that I can practice.

Scott - you've been very helpful - I appreciate it. Right now, I just installed the distributor and are working on the wiring this weekend. Once I get all of that sorted out, I'll be looking at the relay for the fuel pump. If I recall correctly, you had mentioned that I could use the parts of an S-10 Chevrolet pickup... and so, I'll be re-visiting that thread on the forum soon to refresh my memory and will then start working away at it.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,468
I'll look into picking up the line and get some extra length so that I can practice.

Ayuh,.... Pick up a tubin' bendin' tool while yer there,...
It'll make for nice bends, without crimpin' the tubin',....
 
Top