Fuel pressure jumping around

[czimpel]

Just replaced my DW300 pump because my fuel pressure jumped all over the place under boost. With the new pump, I have the same issue. It will rise 1:1 until about 15# of boost, then will drop to 40PSI then jumps around 10-15 PSI.

Could this be a bad FPR? I have a 2 year old Accufab on it.

Possible a boost leak on a vac line somewhere?

I've checked the tank pump to hanger hose again, and it is all fine.

I also am able to put a mighty vac on the FPR and pump it to 30psi and the fuel pressure rises 1:1 and hold accordingly.

 

[dynoman]

I would start checking ALL connections.....start with grounds. As fuel demand increases so does the current
draw from the pump and a poor connection can't handle the extra current needed.

Posted from the TurboBuick.Com mobile app

 

[87GN_70GS]

What is your injector duty cycle? With 120 lb injectors, that pump will run out of capacity at anything over 60% DC (assuming 70 psi total)

 

[czimpel]

I'd have to get a laptop back to check duty cycle. I don't own one for the PL. I wasn't having this issue before. It was working fine, so fuel supply shouldn't be an issue.

The wiring is a good place to start. I have a FP hotwire kit installed, but Nick thought I should fund a ground wire from the back at the pump to the Neg side of the bat. I think I'll start there.