I have a 2005 cavalier. Just replaced the enging with a chevy malibu classic engine, came with a different fuel rail, so replaced the gas lines to match the fuel rail, replaced coil pack, coil pack module, spark plugs, spark plug wires. Showing random misfire. Anyone knoe what this problem could be? Does the computer need reset since it was a mailbu engine? Thanks for any help!

Gas leaks are serious. If it was in the evap system the engine light would be on. So you need to check or have checked the entire system. From the top of the fuel tank, the lines under the vehicle up to the engine(mostly steel) At the engine they turn to rubber or hard plastic. Also check the fuekl rail and injectors. There are two Orings per injector. And check the fuel regulator. I lost my van to a gas leak that ignited from a faulty spark plug wire.

Hello pass.... The fuel pump is in the gas tank. The malibu does not have any fuel filters it only has a strainer on the fuel pump itself. You will have to drop the gas tank to get to the fuel pump.
The Malibu Classic (8th letter of VIN is "F") with the 2.2 Ecotech 4-cylinder engine has a fuel filter between the fuel tank and the rear axle. One end of the filter has a threaded connector and the other is a typical compression style. Regarding the antitheft system, if that is the problem I recommend that you contact an autoelectric repair shop and get them involved as they have the diagnostic tools and the wiring diagrams to get to the bottom of these complex devices. Joe

That is the fuel pressure regulator , the diaphragm ruptured inside . Leaks fuel .

look like this ? $20 some bucks

It needs to be reset probably has a p0440 code in the computer.

Sounds like the fuel pump went bad, or a relay for the fuel pump. My guess it's a fuel pump more likely to have gone bad.

Maybe a coincidence that when you overfilled the gas at the gas station that it put the pump 'over the edge' as far as functioning.

I do not see a connection between overfilling and the fuel pump going bad at that instance, but anything is possible.

SMELL GAS YOU NEED CHECK ALL FUEL LINES UNDER THE HOOD IN THE ENGINE COMPARTMENT.IF GAS IS STRONG UNDER HOOD YOU DONT SEE LEAKING FUEL LINES.YOUR FUEL RAIL FUEL INJECTORS LEAKING OR FUEL PRESSURE REGULATOR O - RING OR DIAPHRAM LEAKING GAS.IF FIND NO LEAKS UNDER THE HOOD CHECK FUEL LINES UNDER CAR FROM ENGINE TO FUEL TANK FOR LEAKS.IF ALL IS GOOD YOUR EVAPORATIVE CANISTER SOAKED WITH GAS OR YOUR EMISSION EVAPORATIVE SYSTEM NOT WORKING. DEALERSHIP HAS TO CHECK AND FIX.

along the frame rail, will need special tools that you can get at any parts store. Remove gas cap to depressurize the system first. You will still have to get agressive with the line, sometimes u think your going to break it.

most likely the fuel sending unit,within the fuel pump assembly within the tank....theres a replaceable printed circuit card within the tank which always gets dirty\worn out and contaminated....its very common on malibu's Cavaliers,sunfires etc...tank has to be lowered to replace it

There is a special tool for this it isn't expensive but it is the only way to safely make the change.

Also - remember to release the fuel line pressure before disconnecting the injector.