SentimentalValue

What the title says. I have just completed a tuneup including:
Delco Opti
Delco Plugs
Delco Wires
Delco Coil
Delco Fuel Filter
Delco PCV Valve
Delco O2 Sensors
CSR Water Pump
!EGR
!AIR
Pacesetter LTs & Y-pipe
New Timing Cover Seals/Gaskets

It ran fine yesterday on the initial run, did plenty of 6000 rpm runs and ran like a champ, now 24 hours later it is hesitating. It can be at any rpm, any gear. If you run up the rpms in 1st, 2nd , 3rd, etc. it will be fine at WOT in 1 second increments, hesitate for a split second, pick right back up for another second, hesitate, you get the picture.

The hesitation is VERY noticeable when in a higher gear, say 5th or 6th and you press the gas down to pick up speed without downshifting, it goes crazy. Doesn't like it at all.

All of the wires are wrapped with the 1200 degree stuff and seem to be all in tact. The intake between the K&N and the throttle body doesn't have any leaks. Two hoses on the motor's intake have splits in them, the PCV hose and the one right under it (both go to throttle body) and they are ordered. The fuel pump in the car is 12 years old so I am going to hook up a FP guage to it in the near future and check that.

What fuel pressure should it read?

Right now I am performing the "Unhook the battery and see if that fixes it" test and I'll let you know how that goes later on.

Please give suggestions, thoughts.

stopthatman

could be those bad hoses. maybe clean your MAF wires? air filter, if you have a laptop you could get a cable and scan it w/ TTS datamaster

OBE1 95Z28

As stated above, fix your vacuum leaks and check your fuel pressure under load.

RedZ28Beauty

If I remember right fuel pressure should be 42-45!

SentimentalValue

I forgot to mention one thing. I didn't replace the fuel filter when I replaced everything else. My initial run was on the 40,000 mile old dirty fuel filter. Once I put in the new filter, it seems it started going downhill. I spoke with the parts guy # mechanic at Abercrombie Chev. in Hartselle AL yesterday when ordering the new intake hoses seeing what their opinion was and the mechanic said something along the line of "With a new fuel filter, sometimes since the fuel is able to run at a higher velocity through the line, the old pump can't keep the pressure up. Any opinions from y'all on this.

It got bad enought last night that it threw the SES light, so I'm going to get the FP guage and get the codes checked this afternoon. I'll keep you posted.

SentimentalValue

Just finished the fuel pressure test and here are the results:

Ignition turned on, engine not running: Fuel pressure spikes to 44psi, settles at 42psi.

At Idle: 36psi

Simulated WOT (pulled vacuum line): 44psi

Actual WOT Run with load: 36psi-42psi proportionally with 2000-5000rpm run.

5th gear pull from 1700 rpm: 42psi.

I believe this is reason enough for a new fuel pump or fuel pressure regulator. Respond and tell me which one you think it is. My guess is the pump. Also, should I go with stock pump and regulator, or aftermarket with higher gpm. My mods are in the sig.