Differential pressure dropping at higher boost

[Volcom86]

I have noticed Fuel Differential Pressure dropping at a higher boost level - ever since I added an EWG a few weeks back, and I am able to turn the boost up - Running around 28PSI currently testing - before we we were running 23-25PSI and there was a slight decrease in differential fuel pressure then maybe 4-5PSI

Now that it is running 27PSI / 28PSI - I have seen up to 20PSI Differential Fuel Pressure / Fuel Pressure drop and my IDC% just over 104% surely this shouldn't be maxed out ?

The fuel base pressure is set at 41.8PSI according to the fuel pressure sensor reading at idle 

Running an EJ257 - the full works

Injectors - ID's 1700x 

UPDATE Running DW300C and not a Walbro 255L 

ai-SP400 surge tank 3 Liter (lift pump - Single Walbro HP In-Tank 460lph) 
Running -8AN lines from the fuel tank to the fuel filter if my mind serves me correctly, then -6AN from the fuel filter to the rails 

The wires have been upgraded and it's running on a relay also - I am not sure if the fuel pumps are running staged - I don't think they are - I have attached the file map for reference also 

I have checked the fuel pump in the surge tank, and no evidence of any electrical issues, the one thing I did find is the fuel hose that connects from the pump feed had no fuel line clamps on the fuel hose line. Not sure if this is normal or not, so I added 2x clamps one on each end of the fuel hose. Might be an issue? I haven't tested yet due to the car being on the lift for works 

 

Thank you in advance for any guiding hand 

Boost-Increase-.pclr

[Joeybratten]

100% having no fuel clamps on the hose can be an issue, once the pressure gets up, it could be leaking internally and bleeding off flow. You can see pressure peaks then drops off, this could be the point that the hose gives and pump starts leaking internally.

Also the fuel pressure D drop matches the Voltage drop, so potentially you're dropping voltage at the pump, maybe be worth hooking up an electrical tester at the pump connection when on boost and see if you're having considerable voltage drop.

[Volcom86]

28 minutes ago, Joeybratten said:

100% having no fuel clamps on the hose can be an issue, once the pressure gets up, it could be leaking internally and bleeding off flow. You can see pressure peaks then drops off, this could be the point that the hose gives and pump starts leaking internally.

Also the fuel pressure D drop matches the Voltage drop, so potentially you're dropping voltage at the pump, maybe be worth hooking up an electrical tester at the pump connection when on boost and see if you're having considerable voltage drop.

Thanks, @Joeybratten thought as much. Appreciate the feedback - hypothetically speaking if the pump voltage does drop on boost, what are my next steps could this indicate a bad pump or wiring not up to the task? Thank you 

[Volcom86]

I did some more testing today, I made sure I had over half a tank of fuel in the tank - I went over the wires and noticed one of the ground cables was loose so retighten that, This log below is from a 3rd gear pull - much better however still not perfect 

Fuel Pressure is about 10PSI - Differential is up and IDC% has fallen down from 104% to 86% 

 

Fuel wires have definitely been updated by the previous owner a long time ago to beef things up

How bad is this to drive at WOT ?? 

What am I missing? 

[Volcom86]

I did some more testing and work, I cleaned up all the ground wires and the chassis for better connection from the fuel pumps - I have tightened the alternator belt, and the results are heading in the right direction. 

The battery V has increased a little with the alternator belt being adjusted. Could I have a bad battery on the way out? The battery is almost 5 if not just over 5 years old 

Going back to some of my older 4 years ago logs, the battery at WOT around 23PSI would be closer to 14V 

Going back to earlier this year a log suggests at 23PSI WOT pull was at 13.6V which is a big drop-off  

[Volcom86]

Ok, an update. Just took out the lift pump and it turns out it is a DW300C

 

Both of the pumps would indicate they run full time, no stages etc from what I can see. 

I am assuming this is too much with both of the fuel pumps being a high volume pump. Would this course the return line to be over fed, and coursing the fuel pressure issues? 

 

Would it make sense for me to get a Walbro 255 in talk lift instead of the Dw300c 

 

Thank you 

[aerace_fab]

What FPR are you running?

[Volcom86]

10 minutes ago, aerace_fab said:

What FPR are you running?

Turbosmart 1200 @aerace_fab

[Volcom86]

Just a quick update - this might help someone one day - I changed the surge tank pump to a 460L Walbro high pressure pump and that has fixed the issue 

 

Thank you all for the help