Zetec fuel rail pressure

[Rod]

I have a 2L Zetec with 45mm Jenvey throttle bodies. Anyone know what the fuel rail pressure should be?



Rod

[slomove]

Depends on your injectors and how high the fuel pressure was when the injection map was generated. Somewhere between 35 and 60 psi is common. I run 40.5 psi with my 30 pound Bosch injectors.
If the pressure is not the same as used for mapping you need to adjust the map. Flow is typically proportional to th square root of the pressure. That means when you increase pressure by 20%, the fuel flow increases by 9.5%.
Also important is that the pressure is stable (whatever it is set to) under high flow and does not fluctuate.

[Sean]

I don't know, but I found a thread on BC that may be of help? here

[Doug Liedblad]

Around 45 PSI.

It may depend on the injectors, I use stock ones in my Jenveys. Works fine.

Small fuel pressure variations are not supposed to make that much difference in fuel delivery. I read that on the internet so it must be correct.

[Rod]

Mine was set at maximum pressure and it failed. My vacuum port on the pressure regualtor was not connected. it had only a 2 inch stub of rubber tubing. Is that normal for a Zetec?

[Sean]

My FPR on the Duratec is set up the same way - vacuum just has a piece of tubing venting to open atmosphere.

[Doug Liedblad]

I believe the port is for when it's boosted.

[sdcat]

I recently broke my throttle position sensor on my duratec and replaced it, and then placed it on the dyno to make sure I wasn't running lean. I am down about 50 hp (160 RWHP dynojet), and extremely rich. The tuner played with the TPS, and thinks we optimized the position of it, but I am still way down in power. My guess is that I added a fuel cell this year with an external fuel pump, and it runs at a higher pressure than the in-tank pump. I am adding a fuel pressure regulator this weekend to bring it down to 50 psi and see how it runs. I am also going to finally buy a new programmable ECU to get things just right!

Justin


On a side note, I am really pleased with the ZZR's with the A24 compound (not the A60 compound which isn't nearly as fast). I've had them on for several track days, and they are wearing well and grip like mad! Sorry, I can't open my mouth without talking about tires!

[Doug Liedblad]

We are hoping to have another dyno day after the first of the year.

Some ECUs allow you to set the limits of the TPS in the software.

The pressure regulator is a good idea.

[slomove]

...The pressure regulator is a good idea....

Well, how do you even run the fuel injection without a regulator ? If you rely on the pump itself, the pressure will be voltage and flow dependent as well as changing with the age of the pump.
I know newer engines have ecu controlled pump pressure without regulator but I am not aware of aftermarket systems that work without regulator and fuel return line. Or am I missing something here?