Advice for Fuel Pressure Regulator Droop

[Tractionless1]

'04 Cobra Budget Return System with DX 340's, DX hat, -8 supply, -6 return, SS filter, DX reg., (dead headed), OE rails, 80's, FRPS in place and operational. System was bought new from Lethal.

With the base pressure at 38, vac. reference off and running pressure at ~35 upon going WOT fuel pressure drops to 28psi then recovers. The fuel pressure was raised to 45 and then drops to 37 under the same circumstances on the dyno proving it's not the pumps. It has been tuned around but not ideal. Is the regulator faulty? It has 415 miles on it.

 

[garbonzo1991gt]

How fast is the droop recovery? A couple seconds? Less than a second?

 

[garbonzo1991gt]

My first guess would be to check your inline filter. Sounds like a bottle neck issue if you have confirmed that your pumps are putting out.

Also, very unlikely, could be a shitty piece of fuel hose that is collapsing or pinched in too tight of a turn.

Another guess would be voltage. Which is a common problem with these cars. Have you monitored/datalogged the voltage when going WOT?

 

[Tractionless1]

My first guess would be to check your inline filter. Sounds like a bottle neck issue if you have confirmed that your pumps are putting out.

Also, very unlikely, could be a shitty piece of fuel hose that is collapsing or pinched in too tight of a turn.

Another guess would be voltage. Which is a common problem with these cars. Have you monitored/datalogged the voltage when going WOT?

Mechman alt. puts out nearly 15v at idle and tuner didn't say anything about it being an issue. He's well versed on the platform and its ideosyncrecies.

I'll check fuel hose this weekend but not sure what difference that would make as the same amount of fuel is flowing at all times. The reg. simply closes down on the return side to send more to the engine. I'll test the vac. line for leaks etc. The SS filter has been out within the past 200 mi. and looked fine.

 

[Tractionless1]

How fast is the droop recovery? A couple seconds? Less than a second?

It happens for couple hundred rpm when going WOT on the dyno.

 

[garbonzo1991gt]

Up top? Down low? In the middle. Also 15v at idle means nothing. What's it do for the entire pull?