bertram31.com

What kind of fuel line am I supposed to use to connect the fuel filter to the fuel pump? Can I use a flexible house with appropriate fittings in this location? If it makes a difference my engines are 454s with log manifolds and mechanical fuel pumps.

My boat came to me with solid lines in this position on both engines. After my starboard engine developed a pin-hole leak in this line my mechanic had a solid steel line fabricated. It is starting to rust rather seriously, and I would like to replace it. Interestingly, the line on the port engine shows no signs of corrosion even though it is magnetic.

I am pretty sure I know what I would do but as I am unsure if it is right I won’t answer.


Magnetic can be Stainless Steel, not all grades are non magnetic and even those grades that are not magnetic can become magnet after cold working which tubing. Tubing is cold worked when formed.

Also could be plated or coated steel

Believe it or not, when I had gas engines, and that line leaked, they made them using metal brake line. I painted the line and it never rusted.

I think this came up in a previous discussion somewhere on here.

My thinking on the matter for carbureted gas engines, is
stainless hard line with flared nuts on the ends for the pressure side of the pump.
On the suction side, rubber hose double clamped at joints, routed in such a way that siphoning from the tank can't happen when the engine is off.
The hard line won't pop off or leak from an overtightend hose clamp, is easy to inspect, wont chafe if routed correctly.

The Rubber may chafe, but is easy and fairly cheap to replace, and if develops a leak, wont spray fuel if its on the suction side.

I'd consult the abyc guidelines on fuel lines for the best opinions.
And be competent enough to know when something is not right if you hire it done.
Fuel lines on gas inboards are one of more serious areas to be overly cautious.

Moreland Hose in Oakdale and i think Baldwin will make up hi-quality braided lines that will last forever. I have used them for years for both my diesel and gas boats. A permanent solution.

Any hose must be USCG type A1 or B1 (mostly for fire). The type approved is the same ID as automotive,
but much thicker walled.

Metal piping has a requirement that there must be a flexible hose connection between hard mounted pipe and the engine.

More info than you want, but may need available here:
https://www.govinfo.gov/content/pkg/CFR ... 83-558.pdf
Best regards,
Pete

My recommendation is that ALL flexible fuel hose be replaced every 5 years leaking or not. The inner liner mandated by the EPA breaks down and will clog various orifices.

When you say AlL, does that go for diesel as well?

Nope not diesel. Just flexible lines manufactured for gasoline, primarily for outboard installations.

Be a little more specific.

When you say ran between the fuel pump and the fuel filter....Are you talking about a fuel filter that is mounted on the engine?

OR

Are you talking about a primary fuel filter that is remotely mounted like a racor unit mounted on the bulkhead wall.

The fuel line that would run from the mechanical fuel pump and go to the carburetor needs to be a metal type tubing. (I am pretty sure that is a USCG requirement). This prevents fuel from being pumped under pressure if a hose failed in that position. I dont know if you have an inline filter in this part of your engine that you are referring to.

If you have the latter, then usually a USCG rubber hose would suffice to go from the remote mounted filter and attach to the mechanical fuel pump.

Fuel filter and fuel pump (mechanical) are both mounted on the engine. I don’t believe there is any danger of fuel leakage because that line is not under pressure. Also I have antisiphon fittings at the fuel tank.