well if any of you remember i found that i was running very lean, i blew up 7 plugs and my 1/4 times started to suck.

anyway went to the dyno and had 13, 15, up to 17 air/fuel.

took it in to get the chip fixed, but didn't matter what they did to the chip, it wouldn't dump anymore fuel....

result: Must be the Fuel Pump!!

makes total sense to me, because after seeing that air/fuel i pulled the chip and ran it off the stock computer and it still felt lean as hell.

 

Could be your pumps or a nicely clogged filter....if its your pumps, you could just upgrade to a set of twin 255s or 305s...

 

Did they check the fuel pressure for ya?

Atchinson here you come....

 

Install a FP gauge ASAP and swap out that filter.

Give it another whirl. What heat range plugs are you running?

 

i change my filter all the time, it is defenitly not the filter!

my NGK TR6's are at .038

see this is kinda what i dont like about livernois, they still have not called me to confirm that the pump is the problem......

 

Check out your vacuum line going to the fuel pressure regulator. If that line isn't hooked up or is leaking it could cause your lean condition.

You may also have a defective fuel pressure regulator.

 

Great advice. The pumps seem to be all or nothing generally.

 

Maybe you put the filter on wrong or installed the wrong filter. I would put a gauge on it rather then throw parts on it and make sure it has low pressure. Check the vac line Don is talking about. Does it have a check engine light or anything>??? -Mat-

 

If the vacumm line comes off the regulator, the truck will run richer because the line pressure will increase. The small vacuum leak caused by a broken line will NOT make the truck run lean, the computer will compensate for the small vacuum leak.

When a regulator goes bad, it normally pops the diaphram inside and either fuel gets sucked into the engine by the vacuum line or it goes full tilt rich, and I mean over 100lbs rail pressure.

NUTTIN BUT THE TRUTH KIDS

 

The little homo is right. Fuel pressure increases with the vacuum off.

If you know anyone with an autotap, check to see if youre pulling codes.

 

Ok I was wrong, but there is a vacuum line that id disconected can make the truck go lean. Take a look on the lower intake on the drivers side below the supercharger. Right in the Middle of the lower intake there is a vacuum line. Make sure that is connected, and follow it to where ever it goes.

I forgett where it goes, but mine became disconected, and it made it run real lean on a dyno pull once.

 

cobra97snake

if you want to try them out to see if it helps. i have the stock rail and fuel pumps sitting in the garage.

 

well, livernois is checking it all out for me, there hooking up a gauge, and trying to figure it out, so far the best they have got it was a 13 to 1 air/fuel which is better than it was but still lean!

 

If the vacuum line is pulled off or came off of the regulator the truck would run rich up until the motor was operating at 0 vacuum. At 0 vacuum it would run stoich and under boost it would run lean. The vacuum line reduces the back pressure the regulator gives when the motor is running under vacuum. And it incrreases the backpressure the regulator gives when the motor is running under boost. This keeps the fuel pressure in the rails at a constant margin above the intake manifold pressure.

 

That's right! and because it's almost always closed loop under vacuum, the O2s will compensate for the disconnect. But when you get to boost and go open loop, it'll go lean, and the fuel trims established under closed loop will make it even worse!!!