Fuel Regulator

[ROGER E]

I think my fuel regulator which is located at the rear of the plenum is bad. I removed the vacuum line to it today and forgot to put it back, then started the car and drove down the block. The car didn't run very well due to the vacuum leak, but I thought that with out the plenum vacuum the regulator should'nt let any fuel pass at all. So if this is the case... is it possible that it is not opening enough during high demand? Or is this just an open or closed type device with no actual regulation properties?

[jonszr1]

no actually you can plug off the vacuum part and get 4lbs increase in pressure . its an old lt1 trick . nothing is wrong with it at all just hook it up and go . or id she running bad?

[Tyler Townsley]

I think my fuel regulator which is located at the rear of the plenum is bad. I removed the vacuum line to it today and forgot to put it back, then started the car and drove down the block. The car didn't run very well due to the vacuum leak, but I thought that with out the plenum vacuum the regulator should'nt let any fuel pass at all. So if this is the case... is it possible that it is not opening enough during high demand? Or is this just an open or closed type device with no actual regulation properties?

I believe you pulled the hose off the MAP not the fuel regulator. This is a 0-5 volt ref signal the ecm uses to calculate fuel pulsewidth. It does a real poor fuel calculation without that signal.

Tyler

[ROGER E]

Thanks Tyler. This vacuum line is visible from the top of the plenum and the device it connects to has fuel lines running throught it. It is black and round with a small 1/8 tube connector on the top of it. A year or so ago I did some engine work and forgot to reinstall this vacuum line then too, and the engine would not fire at all.

[ROGER E]

The car runs fine with it all hooked up. I'm just trying to figure out if the car should fire up at all if this device controls fuel delivery.

[carter200]

Yep, that is the fuel regulator.

[ROGER E]

Thanks Carter. So the engine shouldn't have fired with the vacuum hose removed...right?

[carter200]

Can't tell you for sure but I do know 100% that the unit is the fuel pressure regulator. Sorry I do not have an answer on the starting part:hello:

[XfireZ51]

The vacuum line you pulled off actually raises FP when disconnected because the regulator vacuum port is now at 100% MAP. If anything you're running rich which shouldn't harm the motor. ECM will be pulling fuel out trying to get back to stoich.

[jonszr1]

the car should start with the vacuum hose unplugged. but I dont know why yours didnt/doesnt?

[ROGER E]

Got it. Makes sense now. Thanks for all your help. On a different note, anyone ever try running the LT5 without the secondary port shutters? I bought my engine from Dick Guldstrand and he told me if you do that your gas mileage would go south, but it boosts horsepower.

[lbszr]

Got it. Makes sense now. Thanks for all your help. On a different note, anyone ever try running the LT5 without the secondary port shutters? I bought my engine from Dick Guldstrand and he told me if you do that your gas mileage would go south, but it boosts horsepower.


With secondary actuators removed and a updated computer chip to make it work right I got about 26mpg with interstate driving to BG and usually 18 around home maybe worse since it's hard to keep foot out of it.

[jonszr1]

who did you get to do the updated chip. I am getting ss tired of these pos not working right . did you do any of the work yourself. how hard was it to do? thanx for any advise on this

[lbszr]

Marc Haibeck did the chip. Sent a PM.