Fuel pressure drop and spike

[xyros]

I have a new setup and my logs are showing 0 and 2550 kPa occasional spikes.
I'm running a Reflex MOTIV with a radium fuel return system. A walbro 525 from the Visconti LPFP is providing the fuel for the PI and that is where I have the reflex fuel pressure sensor installed. The return line is regulated at 380kPa.

So, my reflex serial number is 900 and I've heard sn 500-1050 might have issues.

Has anyone experienced this before?

I thought maybe it was a connection problem and I've ensured the connectors are secured and making a good connection.

Any advice on what to try since I've already reached out to Reflex and no response yet.
Thanks!

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[zrk]

Sounds like you have an almost similar setup to mine.

The PI fuel loop is completely separate from the DI loop.

In this case, "2550kpa" basically means zero, there is no pressure in the line. My car reads that same bonkers value when I start the car before I hit 2k rpms, or if the car idles long enough for the regulator to drop all of the pressure.

When do you have the aux pump set to turn on?

 

[xyros]

@zrk It's on all the time. AUX2 is set to 100 in the logs.

 

[xyros]

The pressure only drops to 0 for about 80-160ms and then comes back up. So, I don't think it's a correct reading.

 

[zrk]

Time to get the volt meter out. Chase it all the way back to the pump.

Jump the pump and make sure the relay is good. Skip the relay and make sure the pump is good.

 

[xyros]

It's going to be difficult to troubleshoot since I've only seen it at full throttle.

 

[xyros]

I double checked the ground connection and measured the resistance to make sure that wasn't causing the issue. The relay is working as expected. I am not sure what else to do at this point. Visconti won't even respond to the email I sent and it's his LPFP.

I updated Reflex MOTIV to the latest firmware and reloaded the Ecutek .bin files.

Does anyone know if it is even possible for the fuel pump to drop to 0 and back up to pressure in 80ms? I can only get it to drop to zero for one frame when WOT. It's hard to believe no one else has experienced this before. I am tempted to just tie the PI and DI fuel systems back together at this point.

 

[zrk]

@zrk It's on all the time. AUX2 is set to 100 in the logs.

You have a log?

Did you take the ton meter all the way back to the fuel pressure sender?

 

[2021Supra]

I just had this similar issue a few weeks ago. Even though i could jump 12 volts to the pump at the relay, and make the pump come on, but nothing from the aux 2. The relay would just click. I replaced the relay. Then I relocated the ground wire from where the Visconti directions said, and placed it directly to the negative side of the battery. Then when jumped on from the AUX 2 from Reflex, the pump would come on every time. Just changing the ground wire location fixed my issues.

 

[xyros]

Just changing the ground wire location fixed my issues.

Same solution for me too. Hopefully this helps someone else out in the future. Thanks!

 

[2021Supra]

I agree 100%. I even removed the exhaust again and the tank assembly, to investigate further. Everything was tight and secure inside the tank. Nothing seemed out of place or anything. I kept leaning toward the Reflex and its signal to trip it on. Tuner verified it was on. I said, Let me change this ground wire. BAMMMM, it came on like it should. I even removed the paint from the threaded portion and still relay just clicked.

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