99 SLS runs funny

[goinbig78]

I have a 1999 SLS and in the last month or so performance has been steadily decreasing. I have noticed that at times that the car would seem to hesitate as if the motor was about to die (especially under load). Recently it has started to backfire.

I changed the fuel filter as the problem seemed to mimick a vehicle running out of gas but this had no effect.

Please help.

[Ranger]

Start by pulling the codes. Then check fuel pressure and FPR.

[eldorado1]

Second the fuel pressure check

Sounds suspiciously like a fuel pump problem, but could just as easily be a sensor (MAP or TPS...)

[STS127]

Try a tune-up. Plugs, maybe clean throttle body or run a fuel system cleaner like 44K or Techron.

[goinbig78]

Honestly ive never done any serious work on this car. I have done all the work on my cars but am not familiar with the Northstars.

Do I need any specific tools for the pressure test?

[Ranger]

Just a fuel pressure guage. The tap is on the fuel rail. Looks like a tire valve. Use a guage with a long hose and tape it to the windshield. Watch the pressure when you drive and see what it does under the conditions that cause the problem. If pressure falls greatly when you throttle up, the pump is going south.

[dp102288]

goinbig78, were you able to pull the codes?

[goinbig78]

My sisters boyfriend claims to have gotten no coes on his scanner. If it trully is not throwing a code then what next.

[Ranger]

See post #2. If that is OK, then it's probably time for plugs & wires (A/C Delco).

[clarkz71]

AC Delco wires # 748N, AC Delco plugs 41-950.