Fuel Injection Hose - No Pressure Marking

[V8RX7]

I've bought some fuel injection hose and when it's arrived it doesn't have a pressure marking on it, I'm used to seeing 300psi stamped on it.

It simply states W = fuel hose SAE J30 R6 suitable for unleaded

Google implies that can either be injection or carb hose, it seems that it's burst pressure it around 175psi but some sites state not for Fuel Injection use.

My MX5 is only running 45psi

[GreenV8S]

If it complies with the SAE standard then the minimum burst pressure will be somewhere in the range of 250 psi - 700 psi depending on the hose diameter (smaller hoses taking more pressure). In other words, substantially higher than you need for your application - it'll be fine.

[Mignon]

GreenV8S said:

If it complies with the SAE standard then the minimum burst pressure will be somewhere in the range of 250 psi - 700 psi depending on the hose diameter (smaller hoses taking more pressure). In other words, substantially higher than you need for your application - it'll be fine.

That's not what I see online. R6 is designated as low pressure hose and in the small diameters is rated at 50 psi minimum in the SAE standard although particular manufacturers may produce hose that exceeds that. Continental say theirs is 175 to 250 psi. R6 is also not ethanol resistant.

R9 is specified as high pressure hose for fuel injection systems.

[GreenV8S]

Mignon said:

That's not what I see online. R6 is designated as low pressure hose and in the small diameters is rated at 50 psi minimum in the SAE standard although particular manufacturers may produce hose that exceeds that. Continental say theirs is 175 to 250 psi. R6 is also not ethanol resistant.

R9 is specified as high pressure hose for fuel injection systems.

You're right - good catch. It's R2 which has the higher pressure limits. For R6, the spec says the max working pressure is at least 50 psi up to 3/8" bore, and at least 16 psi for larger bore sizes. This is the minimum to meet the spec and a given manufacturer could exceed the spec.

[Mignon]

Here's the actual SAE paper.

https://law.resource.org/pub/us/cfr/ibr/005/sae.j3...

From Section 6.5.1.1 for hose type R6.

"The minimum burst pressure for hose up to 3/8" I/D shall be 250 psi. The maximum working pressure for such hose would be 50 psi."

That seems to be one hell of a safety margin. Realistically that's not going to fail at normal injection petrol engine fuel pressures. Whether it complies with legal and insurance practices is another matter. If it was my car I'd stick it on.

[V8RX7]

Thanks, I can see that whilst it will do, it's not what I should have been sent.