Fuel pressure issue (1 Viewer)

[UZJ40]

RESOLVED.... SEE POST 6

My Dakota Digital gauge cluster is telling me my fuel pressure is near 100-120 psi, even at idle. I know that is way too high. After talking with a local speed shop today, one of the salesmen mentioned I may have too large of a pump for using the factory fuel pressure regulator. He said the flow is probably 'backing up' at the FPR and spiking the pressure.

Here's my setup-
Unmodified 2UZ 4.7 V8
Unmodified ECU/Tune
All 5/16 feed/return line

OEM fuel tank --> 100 micron Aeromotive filter --> Walbro 255 fuel pump (mounted to frame)--> 40 micron Aeromotive filter --> fuel rail -> OEM (from the V8, obviously) fuel pressure regulator.

I'm sorry for the dumb question, but would it be better to get a lower volume pump or put in an additional regulator before the fuel rail? Would stepping the flow down that much on a high volume pump harm it?

The Walbro pump is 255 lph, so about 67 gallons per hour. I see some Airtex fuel pumps that are closer to 40 gallons per hour. The Tundra engine needs about 43psi at idle.

This is my first time dealing with fuel pressure issues, so any advice is appreciated! Thanks!

 

[Solace in Solitude]

Has it always registered 100-120 psi or is this a new issue?

The Tundra fuel pressure regulator should hover around 43 psi, at idle... If it's really 100-120, it sounds like the regulator could be bad or, as you suspect, the Walbro is overpowering the regulator.

I don't know if restricting the flow further will damage that pump, but if you haven't already, you could verify the accuracy of the Dakota gauge before chasing it further.

Any thought to simply using an OEM pump?

 

[shelfboy1]

ive had to use 2 pressure regulators from time to time to keep fuel flow steady especially on our monster truck ,when the pump was over capacity

 

[White Stripe]

See if your fuel pressure regulator is connected correctly, and test it to see if its working. Or just toss in another regulator from a salvage yard or something. I would think the pump is not overpowering the regulator, but I guess its possible. You could also have a restriction in your fuel line somewhere. Perhaps a hose is kinked from the motor swap.

 

[sadam_husain]

you could verify the accuracy of the Dakota gauge before chasing it further.

X2

if the pressure on the rail was twice what it should be the thing should be running like a dog if running at all

 

[UZJ40]

After another couple hours of troubleshooting today, I figured out the problem. Now everything makes sense, and I know why the car ran so well, indicating high pressure.

Dakota Digital offers 4 different PRESSURE senders, all with different tolerances. In the software of the cluster, there are 5 different LABELS for what you are wanting to indicate. If you label something (like FUEL PRESSURE), it is expecting you to use the 100psi sensor. If you use a 300 psi sensor, the reading will be way off. YOU HAVE TO USE THE SENSOR THE CLUSTER EXPECTS YOU TO USE, DEPENDENT ON THE LABEL YOU CHOSE FOR THE INPUT.

I actually made the mistake of labeling my air pressure and fuel pressure, then hooking them up in the opposite spots. So I was reading my fuel pressure on my AIR PRESSURE screen. I knew I made that mistake, but had not corrected it yet. I had been meaning to when I made a few other wiring changes. Little did I know, it would lead me to hours upon hours of research, buying stuff I didn't need, learning about fuel pressure regulators and all sorts of other fun stuff.

Anyway, thanks for your help MUD! I hope somebody can search for this thread in the future and learn from my mistake!

 

[Solace in Solitude]

Glad you figured it out Riley!

Suggestion... Edit your thread title to something like "Resolved: Dakota Digital: Fuel Pressure Issue" - might make it more searchable.

 

[sadam_husain]

haha yeah that all makes sense mate, well done resolving it so quickly and easily, the truck must run nice with the 2UZ in it

 

[ginmtb]

I wish I had $800 in my budget for a gauge setup like that...

 

[UZJ40]

LOL... unfortunately, it was a drop in the bucket compared to the whole build. The gauges are awesome though.

The issue I just had with them made me really appreciate the thought they put in to them, as weird as it sounds. To me, it is forward thinking to adjust the gauge display according to what you are displaying and what sender should be used in that situation. They just outsmarted me on that one, and it took me a while to figure it out