WHY DO IHAVE O INJECTOR PULSE MY 6 CHEVY2500HD ITH A 6.0L?

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Our Professional Technician writes

Jeff Armer Mar 23, 2022

No,both of them would fire at same time . The PCM supply's a pulsating ground PWM - pulse width modulation . You probably have a fried injector driver inside the PCM - engine computer.

PWM (Pulse Width Modulation) technique, so when the injector gets a signal from the control unit to open an electromagnet moves a plunger allowing the pressurized fuel coming out in a picture of very fine droplets, and this happens when the fuel passes through a very highly engineered nozzle that atomizes the fuel to make it easy to burn, the amount of the fuel determined by the amount of time the nozzle is opened (Pulse Width).

Replace the computer and have dealer program it .
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Thanks Jeff
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If it cranks good but won't start, have a helper crank it while you visually check for spark. If spark everywhere, use a gage and check proper fuel pressure and fuel injector pulse. Any applicable trouble codes?

Have you tried a "noid" light to see if you have an injector pulse? If pulse is present but no fuel coming from injectors the fuel pressure may be inadequate. Use a test gauge to check for proper pressure at key on. Just because the pump runs does not mean the pressure is correct.

Cud b voltage issue. Unplug them and clean contacts. Also u cud unplug computr and clean pins . Older cars have corrosion

Any codes set? If not, run normal diagnostic checks, such as is are the plugs getting spark? Test fuel pressure, check for injector pulse using noid light, and check that timing belt has no broken. Next would be test crank/cam sensor.

2.3 V-6? You should be a 2.5 V-6 whether you have a TBI (throttle body injector) or sequencial, If there is no injector pulse then move your inspection to the distributor, there you will see a distributor pick up, this controls spark and fuel, and yes the rule is if there is no spark then there is no fuel but you case is special you have spark and no fuel pulse,you will need to inspect this for corrosion as it can give spark and no fuel injector pulse,that is one area of no injector pulse, Then inspect the MAP sensor (your a spped density), the most common complaint for a map sensor is it start then dies. inspect this sensor its mounted on the firewall make sure the vacuum hose is connected, and that it is plugged in.

Actually the injectors don't spray "all the time". They pulse open for a few milliseconds then close every time they are grounded by the ECM. The distributor has a pick-up coil (Variable Reluctance sensor) that provides an A/C (Alternating Current) pulse every 120 degrees of crankshaft revolution to the Ignition Control Module also contained inside the distributor. The I.C.M. amplifies, rectifies and passes along the pules as a +12V square wave to the ECM. The ECM uses these pulses to calculate RPM and determine when the engine is rotating vs. stopped. Together with this information and more from Coolant Temp., Throttle Position, Manifold Pressure and Air Temp. the computer constantly 'looks up' what the appropriate amount of time it should pulse the injectors for to deliver the required amount of fuel.
With that in mind, the injectors are supplied with +12V via a 3 AMP fuse labeled INJ 1 for 1 bank of 3 injectors, and INJ 2 for the 2nd bank of injectors. Make sure your injectors are getting +12V whenever the key is ON or they wont fire (or at least 3 won't).
If all 6 injectors have +12V and you have fuel pressure (checked by pushing down in the center of the Schrader (tire valve stem looking thing) valve and fuel SPRAYING out, and your still not getting fuel it is probably because the injectors aren't pulsing. They are probably not pulsing because the ECM is not receiving any reference pulses from the distributor. If you have spark then you are producing reference pulses.
I hope some of this explained from an actual '86 Fiero GT 2.8L V6 owner/mechanic will help narrow down your problem.

The 6 cyclinder motor has 6 fuel injectors. If your not getting pulse Electrical grond to an injector wire theirs a likly chance your not getting it at another. If your getting no pulse at all the engine won't run. Does the check engine light on with the engine running? What meadod did you determine that it had no pulse? Remove one injector wire one at a time with the engine running? If it's not running at all then the no pulse can be a common system part like the crank senser. Does the engine get spark? Most of the time pulse and spark are hand in hand so if the crank senser were bad it's not going to have s[ark either.

CHECK FUEL PRESSURE AND INJECTOR PULSE, IF YOU HAVE A NOID LIGHT. THERE IS A FUEL PRESS TEST PORT ON THE FUEL RAIL. KEY ON ENG OFF PRESS 35-45 PSI IF ITS A V 8 ENG 50-60 IF ITS A STRAIGHT 6. TO CHECK INJECTOR PULSE DISCONNECT THE EASIEST INJECTOR AND PUT THE NOID LIGHT IN THE CONNECTOR AND TURN THE ENG. OVER IF IT FLASHES YOU HAVE INJ PULSE. START THERE AND SEE WHAT YOU GET.