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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15181
Experience:  GM Grand Master Technician 2007. 14 years experience.
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trottle body injectors wont work. fuel pump good, fuel preeure reg.

Customer Question

trottle body injectors won't work. fuel pump good, fuel preeure reg. good.
Submitted: 6 years ago.
Category: Chevy
Expert:  Hal replied 6 years ago.
Does the service engine soon lamp light up on the dash when you turn the key to run?
Customer: replied 6 years ago.
Yes, I've disconnected the battery for 10 mins. the injectors worked agian for about 10secs.
Expert:  Hal replied 6 years ago.
Does the engine have spark after it stalls?
Customer: replied 6 years ago.
Engine has spark. new ing. controller, new coil. Engine fires when primed with gas.New fuel pump relay and op. relay
Customer: replied 6 years ago.
I'll send you fifty bucks u give me an answer that works, Thanks Bill
Expert:  Hal replied 6 years ago.

Well Bill that would be nice . but I am still trying to get a grasp on what condition you have going on with this truck. There have been allot of parts replaced, with no help yet.

I want to help you diagnose the concern correctly so you don't waist money on something that is not needed.


Ok I just want to run down what you have done so far.

1) replaced or verified fuel pump is reaching 9-13 psi. Have you verified this when it stalls?


2) Fuel regulator is good. ( I have to assume that means you have verified fuel pressure) Correct?


3) the ses lamp will come on with the key in run. Are there any codes setting?

( the SES lamp on verifies the ECM can enter diagnostics)

ground the A B terminal and SES lamp will flash trouble codes three times. Code 12 will always come up.


4) If you disconnect the battery ( this clears trouble codes) It will run for 10 seconds.


5) engine has new ignition module, new ignition coil. and has spark when it wont start.


6) If you pour gas down the throttle body it will fire. ( how long ?)


Can you verify the injector pulse is not there when it stalls? hook a test lamp to battery positive and touch the terminal on the injector connector going to the ecm ( the one without power with key on) Does it flash when engine is cranked?


Try only running on one injector. One injector may be shorted. This engine will run with one injector hooked up( you may have to hold the throttle open sightly.


Try both sides is there any difference?


Measure the resistance of the injectors. ( note this computer ( ECM) is anon protected ECM. If there is a solenoid or injector that is shorted it will damage the ECM)


Measure the resistance of all solenoids that are controlled by ECM.

Torque converter clutch. AIR control solenoids/valves. EGR solenoid No solenoid should be under 20 ohms. Or any new computer that is plugged in will be damaged the same.


This is allot to grasp all at once so I will please ask you to look through the list above to make sure I have it straight every thing you have done so far.


Then run the checks I have listed . We need to verify what is working correctly to be able to determine what is not. Thanks Bill


If you need to know more on how to test these items, I can walk you through it.


Thank you for being patient, we will get this running!