Looking for some suggestions

[TRBO VNM]

Ported eaton
4# lower
60# injectors
stock MAF with mafia
stock pumps with BAP and wire upgrade
JLT RAI

Logging the car during a pull fuel rail pressure is dropping and actually gets down to about 14psi. A/F stays in the 11's until it hits that low and spikes to 12.0 or so and then drops back down in the 11's. It's like the pressure is fine at idle, once hitting the gas is starts dropping and is at its lowest point in the 4000-4400 range and then comes back up, but only to 22 psi.

Based on A/f the car is doing what it is supposed to and opens the fuel injectors to try and maintain the a/f.

Pressure drop across injector also drops as I would expect based on the FRPS readings.

Doesn't appear to be belt slip and if so, I would assume it would show rich and not lean? FPDC is 84%, so I wouldn't think there is a pump issue or hole in a hose in the tank. Fuel filter has been replaced.

Only other thing I can think of is socks on the pumps? I am stumped and that rarely happens. LOL

 

[01yellercobra]

What's the voltage doing when all of this happens?

 

[TRBO VNM]

Forgot to mentioned that, good call. Lowest it went was 12.75 at around 5400 rpm.

 

[toomanytoys]

Doesn't have a pprv elimination does it?

 

[TRBO VNM]

Doesn't have a pprv elimination does it?

No it doesn't, but we are going to do it this week. Changed pumps to another set of stock pumps with their fuel lines and pprv that were removed from a low mileage car and it still has the issue. Actually crazy that at idle fuel rail pressure is about 17-18psi now. New FRPS sensor as well and swapped with another sensor to confirm.

And what is crazier, put another base tune in it and then the rail pressure is reading correct. Went back to a tune that was previously logged and showing good pressure and this time showed low pressure. Honestly have never seen something like this before. How a known good file, with good log shows low pressure the second time it is loaded in is beyond me.

If it is a pprv issue, which I doubt, I can't see 2 different pprv's having problems when they were both perfecting fine a few weeks ago. Even tried wiggling the FRPS wires to see if there was a connection issue and that seemed fine.

Might remove the BAP from the system and see what happens. I triple checked the wiring and it is fine.

 

[toomanytoys]

Could the pressure coming up from the tune change just be coincidence ? Dirty contacts on the pump relay maybe?