Reviewing scans and watching a narrow band 02 gauge (Yes I know.... but it was installed by PO), I almost never see the car go rich and am running High BLMs. Additionally, after the car sits for a few days I have extended cranks times.

Thought 1, FPR is bad and it is running off the oil pressure switch, resulting in voltage at the pump being low. This is not the case, Key on, pressure comes up immediately.

Thought 2, Main pump going bad. I have a secondary with the supercharger kit, but it is up front. We all know the electrical pumps want to push not pull. So if the main pump isn't doing it's job the secondary pump can't pull the fuel to it. It's not just under boost, but part throttle where the main issues are, but not getting to the rich side under WOT, so BLMs are still show short on fuel. Went for a drive, monitored pressure saw very little movement on the gauge if any as the vacuum changed under part throttle. Though, under WOT, fuel pressure came up. On my other cars, Fuel pressure responds quickly to throttle input and vacuum drop.

I would think even if the main pump was compromised part throttle shouldn't be where the main problem would be. I was anticipating seeing fuel pressure drop with load and RPM, but it did not. And then came up under full throttle. So it seems as thought the system is capable of supporting what it is being asked to supply, but the vacuum drop doesn't seem to be commanding any increase.

So, is it as simple as I need a new FPR? It currently has a stock style FPR. I do not know if it is original or not. Car has ~63K miles, running a Vortech Hot Air Kit with boost referenced timing retard (1 degree per pound of boost) with a FMU for the second pump. Which back to thought 2, if the FMU is not letting the second pump help much anyway at Key On... then it would't be able to start the car. However, I know I have pressure at key on.

 

Fuel Filter is obviously pretty new.

Fuel Pressure test in June 19:

KOEO: 42PSI
Idle (W/Vacuum): 38PSI
Idle (W/O Vacuum): 46PSI

Leak Down
0 min: 42PSI
5min: 34PSI
10min: 25PSI
15min: 22PSI
20min: 19PSI
25min: 18PSI
30min: 16PSI


Today (8/24/19)
KOEO: 42PSI
Idle (W/Vacuum): 36PSI
Idle (W/O Vacuum): 45PSI

Leak Down
0 min: 42PSI
5min: 40PSI
10min: 34PSI
15min: 20PSI
20min: 16PSI
25min: 12PSI
30min: 5PSI

FPR Vacuum Line is dry

 

With a Vacuum pump attached, No vacuum is 42, can pull it down to the low 30s (should have looked closer). Justed use my vacuum bleeder to generate the vacuum.

Then gave ~8-10psi of positive pressure and it jumped up to 58.

All this happened quickly. So, I am going to rule out the FPR. With direct vacuum and pressure it responds properly and quickly.

So, with the vacuum/Boost gage in the car showing proper readings,... Wonder why the Fuel Pressure isn't responding?

 

All back assembled, I see very little movement in pressure when I grab the throttle and rev it a bit. Seems like the needle should twitch some. Going to check on my other car as well. I wouldn't think a check valve could slow the response, but it's the only thing between the manifold and the FPR. Manifold line comes out, hits the check valve. Two ports on the other side. 1 to FPR and one heads to the firewall for the HVAC controls.

Seems to check ok on the Bench. Though, consider the FPR never sees the positive manifold pressure because of the check valve. It should.

 

Confirmed on my other car, fuel pressure jumps qucikly with throttle response. Looks like I need to get a different check valve with only one port on the other side from the input rather than 2. Time for a parts store trip.

 

Picked up a single port check valve, t'ed in before the check valve to go to the FPR.... Fuel Pressure now jumps up quickly with any throttle input and will be able to see boost. Problem solved.

 

Throttle response greatly improved. Going to give it a few rides before data logging again. Give it a chance to learn with the higher fuel pressures it will see then see how the BLMs are doing. I still think it runs a bit to the lean side.