I was hoping for some assistance regarding fuel pressures on a BA XR6 Turbo. I did a turbo engine swap on my BA wagon including fitting a Walbro GSS341 pump into the stock cradle. The FPR is the stock Bosch 0280160575 unit.

 

I noticed there seemed to be a bit of hesitation during acceleration so I fitted a fuel pressure gauge to have a look. At idle with the old FPR and the manifold reference line connected it was sitting at about 47psi. After removing the manifold reference line it only increased to about 51-52psi fuel pressure. I thought either the gauge was out or the FPR was faulty. I installed a different second hand Bosch FPR to see if the reading on the gauge was the same but it now read higher so I think my FPR was faulty. 

 

Now when the pump primes the gauge shows about 58psi which is good. When the manifold reference line is connected and engine is idling it shows about 51psi. With the engine running and no reference line it shows maybe 55psi which I am not confident is good. My question is relating to the reading under boost. The engine has a 7lb wastegate actuator fitted and under boost the car is making about 9 psi. I would expect the gauge to show approx 67psi but it only shows 61-62psi fuel pressure. Am I right in thinking that this FPR is supposed to be a 1:1 ratio and that my fuel pressure should be higher? I did have a search around on here and couldn't really find solid numbers on what I want to know. Lots of info about Pierberg pumps and FPR1200's though

 

Although it is a complete pain in the butt, I do plan on pulling the tank out to check out the corrugated hose fitted to the pump as I have read it splits occasionally.

Edited January 16, 20188 yr by jrmr

Ok so you’re on the money with what you’re thinking 

 

base pressure without reference line 58psi 

connected referance around 52psi 

 

aftermarket FPR’s typically 1:1 ratio 

 

the situation is that not all pumps and installations are 100% identical 

you can have a base pressure whatever you want within reason as long as the PSI above Ambient raises the FPR at a 1:1 there’s no issues if the Lambda target is set correctly 

 

in your case I would get a new ( or even second hand ) factory FPR and plum it all back up and work with what you get as it’s all very close PSI wise and tune the target to suit 

 

if you want you can troubleshoot the system and all the flow rates are available for your hardware but I seem to think you probably won't see to much other than a potential slight high pressure leak from the pump/hose area if it was installed incorrectly and assuming all new hardware 

 

the fuel lines in the turbo falcon are pretty good but there has been the occasional blockage beforehand and you could have something similar, failing that check voltage supply and fuse/cable current ( Amps) condition and battery condition 

 

cheers