: 1996 Northstar Excess Fuel Consumption



frankg70ss
07-11-05, 09:49 PM
My 96 SLS fuel mileage dropped after my fuel rail was replaced in a current recall.I returned it to the dealer and the replaced one plug and wire and one injector.The car will have a flat spot or miss during acceleration and the tail pipe gets black with an over rich condition.Sometimes I will get a ses light code PC0300 engine misfire detected.The engine is also hard starting when cold.Do I have an ignition problem or is it fuel?The plugs have been replaced but not the wires.Any help would be appreciated.Thanks

Ranger
07-11-05, 10:20 PM
My money is on the wires. I, as well as many others have had a misfire develope right after the fuel rail replacement. Replace the rest of the wires with OEM wires. Also check for a leaky FPR.

mcowden
07-11-05, 10:39 PM
My money is on the wires. I, as well as many others have had a misfire develope right after the fuel rail replacement. Replace the rest of the wires with OEM wires. Also check for a leaky FPR.

Agreed with Ranger. Many people posted about misfires after the fuel rail recall service was done, and wires has been the number 1 suggestion. As far as I know, no one has come back to complain that it didn't work. I also have a 96 SLS, and had misfires before the fuel rail was replaced. At about 85k miles, it started with an occasional miss, then it got worse and worse. The wires fixed it right up. Now I'm at 95,5xx and still running great. I would start with the wires, especially if it's got more than about 70k on the clock.

The fuel pressure regulator is easy to check. It's the only thing on the fuel rail with a vacuum line attached to it. Start the engine and pull the vacuum line off the FPR. If fuel leaks from the nipple, the FPR is bad and needs to be replaced. That will definitely cause a rich condition and hard hot restarts. Other than that, they might not have seated an injector or an O ring properly, or maybe an injector is leaking.

Start with the wires. You will need AC Delco wire set 748J, and you can find good prices at www.rockauto.com or www.gmpartsdirect.com. The plugs should be AC Delco 41-950. If you have Bosch plugs in there, replace them with the good stuff because the Bosch's are junk.

frankg70ss
07-28-05, 10:56 PM
Thanks for the help I will change the wires first.

zonie77
07-29-05, 02:12 AM
Several people had wires act up after the rail was changed. Probably from being pulled off. If they were on for 10 yrs they did not come off easily. Don't forget to check the FPR though.