99 blazer stalls

[jimrock83]

i have a 99 blazer it stalls at idle and or while driving no check engine light or any thing if you turn the key back to the off position after it stalls for about 5 seconds it will start back up some times it will run for a hour but then stall agian ive repaced the fuel pump,fuel filter,cat ,02 sensor, computer,plugs,wires ,coil, cap ,the voltage thing next to the coil,checked the vacuum lines they all look fine any help or suggtions would be very hepful thanks

[MT-2500]

When it does it check for lose of fuel/fuel pressure.
Check for lose of spark at two or more spark plugs

[MT-2500]

When it does it check for lose of fuel/fuel pressure.
Check for lose of spark at two or more spark plugs

[muddog321]

If fuel and spark good and this is at idle only, I would have to say look at the idle air control valve (IAC) on the side of the throttle body. One of mine did this very intermittently and that was it. Have to remove the throttle body to get the 3 torx screws off and then also clean the air passage or seat for the IAC - this controls the idle rpm via the PCM controlling the air/fuel mix. Before you spray it down also pull the throttle position sensor (TPS) off so you don't destroy it with the cleaner!

[discnik]

When removing the Throttle Position Sensor make sure to mark the sensor and housing so you can install the sensor in exactly the same position it was in. If you do not you are going to create additional problems

[kappy1]

does it idle rough before it stalls? EGR valve gets plugged with carbon deposite will run or stall at low idle may need to replace or just clean it out

[jimrock83]

no i checked the egr and it is fine and i also cleaned the throttle body it is all clean and it still stalls

[MT-2500]

When driving does it only stall when you let up on gas or when it is driving steady?
If just stalling when you let up on gas or idle.
Check the IAC contol and related parts.
But if it stall when going steady down the road you need to check for lose of fuel pressure or spark or injector pulse.
Start with a good fuel pressure check.
Tape a fuel pressure gauge to outside mirrow or outside windshield and drive it and watch your fuel pressure.
Post back fuel pressure readings.
MT

[jimrock83]

fuel pressure is at the right specs it is a spark issue for sure know it won't start at all now no spark im going to test the ignition switch next thanks