High Pressure Fuel Pump - two hard lines!?

[aweds]

I was attempting to replace my cam follower, all was going well until I encountered a 2nd hard line on the left of the fuel line (I think it’s normally a soft/flex hose)

Anyone experience this - photo below.

[ZoliWorks]

There's 2 generations of HPFP lines used in the mk5. This one is the old gen. The newer gens use the rubber hose because it makes maintenance much easier but other than that, there's not much point in upgrading. One thing you can do tho is drill out the limiter in the end of this hard fuel line. This eases the stress on the LPFP, making it last longer and also helps with fuel demand if you're running an upgraded HPFP.




I drilled mine out to 4mm, plugged the part that goes to the fuel return valve and flushed the other side out with compressed air and brake cleaner so no metal fragments are left.

[pudding]

Drilling it out is a popular mod but it reduces the LPFP head pressure. Bigger holes increase flow, and therefore pressure.  The OEM 2mm hole or what ever size it is, is plenty to fill the HPFP. If more LPFP rate is needed after doing HPFP internals, then a TTRS pump is the better solution.

[ZoliWorks]

Drilling it out is a popular mod but it reduces the LPFP head pressure. Bigger holes increase flow, and therefore pressure.  The OEM 2mm hole or what ever size it is, is plenty to fill the HPFP. If more LPFP rate is needed after doing HPFP internals, then a TTRS pump is the better solution.

I was told by the guy over at Vis Motorsport that it helps with lpfh lifespan cause it reduces the stress on the pump and will also help keep the hpfp supplied better. Do you reckon it could cause hiccups when flooring the car? Every once in a while, the car just hiccups for a second then picks itself back up. Or would this more likely be caused by a faulty injector instead?