I've read in a couple of threads that the fuel flow is backwards relative to a USDM S5 Tii. The My NA to Tii JDM Swap!!! being a common example.

But in spite of searching I can't find out exactly what that means. Here is the FC3SPro illustration of the fuel system. On my JDM S5 Tii, it looks exactly like this. The pulsation damper and the fuel pressure regulator are in these same positions. The fuel hoses shown connect to hard lines in the rats nest but otherwise, the diagram is spot on.

So does the fuel in a JDM S5 Tii flow opposite of the arrows in this diagram and hence goes to the FPR first, the secondary injectors second, the primary injectors third and finally the pulsation damper last.

Is that what folks mean by JDM fuel systems being backwards?

Thanks

 

Yes.

Flows through the secondary rail first then the primary...

 

where does the fuel flow through the pulsation damper on the Jspecs? Before the secondary or after the primary?

 

Cool, thanks. I was frankly leaning towards an Occam's Razor scenario where the pipes coming out of the rat's nest were swapped. So this is helpful.

Thx

 

On my 87 TII JDM the regulator is on the Primary rail and the damper is on the secondary rail. The fuel flows through the secondary then to the primary. That threw me off the first time I saw it.

 

I never heard of this...
Im in the middle of finishing my swap. ANd i got confused on how the fuel flows..

From the fuel filter does it go to the primary or secondary rail?

 

maybe you didnt read the previous posts? its already been said twice.

 

To make it really simple, on my JDM S5 Tii the front fuel line is the input. So on mine the line comes up and out of the fuel filter and goes to the front-most fuel hardline.

This is fresh for me because this weekend we found a fine mist of gasoline spraying out from that line right near the fuel hardline. Thinking this might be dangerous, we replaced the line.

 

Bringin this thread back...

I'm seeing some contradicting information here

Fuel flows backwards when referencing the diagram above.

Fuel always hits the FPR last.

On my jspec s5 tii engine, the PD Is on the primary rail, and the FPR is on the secondary rail.

Does my fuel still flow backwards?

If not, why is my fuel set up like a USDM Fuel system, when my engine is bone stock????

 

i looked this up in the JDM parts catalog, just because i was curious, and here is what i found.

the S5 fuel system is the same, US and JDM, they both have the damper on the primary rail and the pressure regulator on the secondary. both use the same part number parts, so they are identical.

the US S4 T2 and the HC Luce, use the same system, its setup like the S5, but uses the S4 rails which are cast, and the damper and regulator are separate. damper is on the primary, and regulator is on the secondary.

the JDM S4 T2 is the weird one. it has the damper on the secondary rail and the pressure regulator on the primary. no idea why, however it looks like the fuel flow is reversed, it goes in the secondary rail and out the primary.

 

Good info.

So it looks like JSPEC S4 TII engines are the only fuel systems that flow backwards.

Done deal.