Is the anti-theft light lit on the instrument cluster ? Won't start how ? When you turn the key to start , what happens ? Nothing ? This would be a No crank - no start condition . Now if you turn the key to start and the starter engages and spins the engine and it doesn't start an run , this is a engine cranks no start condition ! Now which is your problem ?
There are two fuse's IGN A fuse 40amp and IGN E fuse 10amp ,both are located in the under hood fuse/relay box . Also there is starter relay located in the same under hood fuse /relay box . There also is a crank fuse 10amp in the under hood fuse box . Besides the fuse's and relay ,the ignition switch or the PNP - park neutral position switch could be bad . Testing the whole starter circuit should be done ! How to voltage drop test starter motor circuit
they have a controll module afixed to the wiper motor itself. these modules have been an issue for gm for some time. they are very simple to replace and "usually" fix the issue.
A misfire could be caused by a bad , clogged fuel injector . A vacuum leak . How are you reading a misfire ? A code ? A dirty mass air flow sensor can cause misfires . Low fuel pressure ,clogged fuel filter . When you replaced the fuel pump did you replace the ceramic sending unit resistor card with a new one ?
Fuel Gage
The IPC displays the fuel level as determined by the PCM- engine computer. The IPC -instrument panel cluster receives a class 2 message from the PCM indicating the fuel level percent. The fuel gage defaults to empty if:
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The PCM detects a malfunction in the fuel level sensor circuit.
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The IPC detects a loss of class 2 communications with the PCM.
When the fuel level is less than a pre-determined value, the low fuel indicator illuminates.
Reviewing the fuel system description will further explain how the system functions. Refer to Fuel System Description .
Do you know about class 2 serial data communication .
Do
First check the drive shafts(vibration). Universal joints could be bad. Best to have it off the ground. No pressure from the tires and transfer case/transmission. Service 4x4 has to go on a scanner to get codes. Check fuses first.
