Couldn't get my S4 13bT to start, realized the injectors werent getting fuel. The supply line was well pressurized and nothing was coming out the return.
So I checked on the net and found a couple of diagrams of the fuel system. The supply line from the pump is meant to feed the primary (lower) injectors first correct? So the return to the tank comes from the reg at the end of the secondary (upper) rail correct?

I swapped the lines around (the wrong way!) and the engine now runs perfectly since the injectors are getting fuel. It simply won't run with the fuel flowing in the direction shown by a few online diagrams.

Does this mean the regulator is stuffed? Or is it the pulsation dampener? What would be the best fix?

Thanks in advance for any ideas/thoughts/opinions!

 

The feed line goes to the side of the primary injector rail with the pulsation damper. Then the fuel return to the tank exits from the pressure regulator.

J-spec engines have the hard lines on the vacuum rack reversed.

 

So mine must be a Jspec engine? If I only get fuel flow to the injectors with the feed to the reg on the secondary rail?

 

The non-turbo engines feed in the opposite direction as turbo engines, so make sure you are looking at the correct diagrams. I think the factory service manual has diagrams that will show how the fuel should be routed, but make sure you are in the turbo engine chapter.

 

Will check the manual. Thanks for the info guys

 

Speaking of USDM engines, the NA and turbo engines both flow fuel to the primary rail, then the secondary rail, then the FPR, then back to the tank.

Some of the JDM turbo engines flow fuel to the secondary rail, then the primary rail, the FPR, and back to the tank.

 

The rails flow in opposite directions though...

USDM non-turbo: PD > front primary > rear primary > rear secondary > front secondary > FPR

USDM turbo: PD > rear primary > front primary > front secondary > rear secondary > FPR

Regardless of the engine type, or whether or not the engine has a modified or custom system, the fuel should always flow into the FPR last.