Hi all, New to this site so be gentle

I have been chasing a low fuel pressure fault for awhile now and struggling to get to the bottom of it
symptoms are coughing and spluttering at 4 1/2 thousand rpm
I have an ultra gauge fitted and I can see the rail pressure underload fluctuate between 1800 and around 300 psi
Sometimes it will rev all the way through the rev range until 6 1/2 7000RPM
Most of the time it costs and splutters at higher rpm

So far, I have tried a new low pressure fuel pump genuine used one I have also fitted a aem. 400 LPH fuel pump
I have replaced the high-pressure fuel pump with a known good one
I have removed the fuel filter housing replaced the filter and cleaned it
Replaced injectors with known good ones
I have had the foot well module part to check sold a joint on relay they looked good. I re-sold them anyway just to be sure

I really am struggling with this problem, it’s my track toy and we’re coming into some good weather now and I’m really want to get to the bottom of this problem

Any advice would be very grateful any point as you can give me anything I’ve missed please fire me over some information or pointers anything I need to look out for or anything I may have missed

Many thanks, Antony

 

I've heard of the AEM lpfp not being the best for these. I would try a stock one and see what that does. Also, I would check the fuel rail sensor. Maybe replace that with a well known one. And then anything else, will be fuel leaks anywhere? Something wrong with the evap maybe?

 

Yes I was told that too about the AEM pump so I removed it and replaced it with a used genuine pump and still the same

forgot to mention that I have also swapped the rail pressure sensor too..

I have a few minis to my disposal so have many spares to play with

as for the evap, I hadn’t thought about that..
in fact I’m not even sure my car has it.. I can’t remember seeing a charcoal canister anywhere
would it be located next to the tank?

 

Yes, I believe it's right next to the tank. Are you tuned? Any check engine lights?

 

Yes it’s tuned, Hybrid turbo etc
285 hp

i have had the standard tune put back on also to see if it was a problem with that but no luck there

No engine lights, no faults pending
just going off the information on the ultra gauge

 

Next thing that comes to mind since you changed the injectors with used ones. Did you change the seals with brand new ones? I'm talking the Viton seals. Not the o-rings that go in the rail itself. If not, possibly could be a small enough gap that is letting in air or letting fuel escape.

 

Here is a short video of what is happening with the car
sorry for poor quality and length
it wouldn’t let me upload a longer one

scrap that. Can’t get it to upload. Will do it at home on pc later

 

Maybe relay solder joints were fine but the relay was faulty?