ae 92 fuel pump pressure

[I wish]

Can any help me? I need to know what fuel pressure should I have on a AE92 4agze? Previous owner put aftermarket pump on the car and the fuel disappears from the tank real quick.

[rebuilder86]

33-40 psi at idle
38-40psi pump on, engine off.

Edited June 21, 2018 by rebuilder86

[ke70dave]

And it should get lower when vacuum drops. 

[rebuilder86]

the fuel pressure gets lower when vacuum drops??
vacuum drops when load is applied or throttle is opened. u sure of that, or am i thinking something wrong?

[I wish]

Thanks for that, I'll get a pressure gauge and check mine out. 

[altezzaclub]

Got any figures for fuel use in L/100Km??    Maybe its quite normal.. 

"the fuel pressure gets lower when vacuum drops??"

That depends on what Dave means by a vacuum dropping. The vac operated fuel pressure diaphram makes it richer as you open the throttle and the vacuum reduces, and then the high vacuum of a closed throttle drops fuel pressure as you lift off, a cheap fuel injection version of an accelerator pump.

 

[ke70dave]

I think i got it the wrong way around but the purpose of the fuel pressure regulator is to keep the pressure drop the same across the injector with changes in vacuum. 

at wide open throttle you have pretty much zero pressure in the inlet manifold. but at idle you have low pressure (vacuum) in the inlet manifold.  so in order to  keep the same pressure drop across the fuel  injector the fuel pressure reduces at higher vacuum....i think thats it...

so you might have 32psi or so at idle, then when you stab the throttle it jumps up to 38-40psi. 

 

[altezzaclub]

Well, I wonder which reason they did it for?  The pressure difference is important or the accelerator pump is important?

The high fuel pressure richens it for acceleration(11 or 12)  and when its cruising it goes back to 14.7.  I'm running the mixture display on The Girls 4AGE and it will go down to 16 or 17 on over-run, so it leans right out.

After the head rebuild the display showed it was running at 13 or 14  a lot in times when it never used to, and sure enough it used 7.9L/100km instead of under 7 like it usually did.  I don't know what has changed to do that.

[rebuilder86]

It seems there is a little confusion over the FPR's role. In a non turbo it keeps the pressure constant all the time.

In The AGZE, it does this, up until boost where then increases pressure. So u shouldnt realy see an increase untill ur actually driving, or on a dyno, or really really stabbing the throttle.