Does anyone have an Accel adjustable fuel pressure regulator? Which way is Rich or lean? clock wise or counter clock wise? Also, Does the car need more fuel or less fuel if you have to pump the gas a couple of time to get it to turn over. My fuel pressure is reading around 50 at idle but when you hammer it it drops way down.

Thanks.

 

Clock wise adds pressure. You should be around 38 at idle and jump to 43-44 at wot. You may have a bad pump or plugged fuel filter.

 

I have a brand new pump. Are those pressure reading for a stock LT1?

 

Yes, in that general range.

 

I'm not quite stock. I just have the usual stuff, cam, ported intake, headers ec...

 

Doesn't really matter what you have in the way of mods, except as noted below. With a stock fuel system, and under about 450HP, you should see the fuel pressures mentioned above. Factory spec, with the vacuum line removed is 43.5psi +/- 2.5psi, so anything between 41-46psi is within spec. Connect the vacuum line, and the rail fuel pressure should drop proportional to intake manifold vacuum... stock that would be about an 8psi drop from the "no vacuum" value. With a healthy cam that might only see a 4 to 5psi drop in fuel pressure.

So.. when cruising, with high vacuum, you would see the lower value... perhaps 38psi. But when you go WOT, the fuel pressure should RISE to the same value as the "no vacuum line" pressure... or about 41-46psi.

Seems odd that you have 50psi at idle... that is outside the stock specs. And if your pressure drops at WOT, you either have a failure of the fuel system to supply enough fuel, or the FPR is screwed up.

On top of that, tuning A/F ratio with an AFPR makes no sense at all, since the PCM will detect the revisions to fuel flow caused by the pressure change, and will adjust the long term fuel corrections to compensate. You can't win.

The correct way to tune it in the PCM, with changes to the PE tables. An AFPR is only usefull for increasing fuel pressure to increase fuel flow capacity of the injectors. But before you do anything, you need to understand why your fuel system is not repsonding correctly.

 

Well...I had the PCM reprogramed for all the Mods done to the car. The thing is that when the car is "cold" just after start up ir runs good. After the car reaches normal operating temp it starts to "chug" especially at lower RMP's. When I'm in overdrive and get into the throttle the car starts to shake until the tranny shift down. I actually heard it kind of "back fire" through the Intake a couple of times when I tried to get on the throttle.

 

When you had the "program" done, did you tell them the correct injector size and brand? ...the fuel pressure you intended to run at? ....the altitude you run at?

I'd push the problem back to the "programmer" and get it done right, rather than putting a band-aid like an AFPR on it and trying to patch it up.... just a thought

 

Yeah, your probably right I'm going to get a hold of the company who did it.