Fuel rail issue while upgrading to stage 2

[Abs2788]

Hi

Just fitted my milltek - full system from turbo; induction kit, pcv upgrade to type n; new used fuel pump as I was having limp modes before and before carrying out stage 2 remap and performing dyno runs, still having the dreaded fuel pressure error and going to limp on standard.

My fuel rails are the old banjo nut style which has now rounded and leaking so I'm trying to source a new type fuel rail line (hose connection) found on the newer cars if someone can point me in right direction.

At this point I will also look to upgrade to rs4 valve as well while it's all off.

Can anyone shed any light to this issue, I've swapped sensors as well etc and still at around 4,500rpm on dyno, it drops to around 25 bar Idle is at 50 bar

Any advice or help I would greatly appreciate

 

[MJ]

fuel filter? lift pump?

 

[Abs2788]

I personally don't think it would be fuel filter because that was changed with a service in august, and is the correct bar that was used. The lift pump we have changed on the new fuel pump I purchased but cannot test with out the new fuel rails as my banjo nut rounded off and leaks fuel on ignition

 

[MJ]

by lift pump I mean the one in the tank buddy.

 

[Abs2788]

Can you point out what you mean exactly by that? Picture for example or part number etc thanks for your help

 

[MJ]

There's an electronic fuel pump in the fuel tank, under the back seats behind the driver.

 

[phillbriggs]

Sounds like a bad HPFP, pull it of and take it apart, inspect the piston & sleeve for damage or wear and make sure its actually a uprated larger piston. I had fuel pressure problems on my road car which turned out to be the fuel pump internals binding when hot & at high revs. Fuel pump was actually sticking in when hot despite being spring loaded. also check the cam lobe & follower for wear. Im not sure was what stage a rs4 relief valve is required on the HPFP.

 

[Abs2788]

I've changed the spring on the second hand one I bought on eBay, on off chance this could be a bad one as well. Changed cam follower while off as well. Only issue was when putting it all together to go back on run, the stupid banjo nut rounded off while tightening. Now trying to source new fuel lines with the hose connection before I can re-test on dyno

 

[phillbriggs]

Its not the spring that fails but the internal piston & sleeve behind it, strip down the pump & check the internals over & also check its actually a uprated pump with larger piston, otherwise it will never gain enough fuel pressure especially mid range.