Throttle body injectors not fiering but there is fuel pressure
My 94 sierra will not start all of the time and dies some times when driving. when it will not start the throttle body injectors are not spraying fuel but the fuel pump is working and there is fuel pressure and the throttle body it just dose not spray fuel. what would cause the injectors not to fire.
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Re: throttle body injectors not fiering but there is fuel...
The injectors are fired thru the engine cotrol module but it gets its signal to fire from the pick-up located inside the distributor if you are loosing injector pulse only the ignition module is bad if you are also loosing spark when you loose injector pulse your pick up is causing the problem if you replace the pick-up i recomend you change the ignition module when doing so because they work together and you have to remove the distributor to change the pick-up
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What testing have you done?
I looked at info for 94 blazer 5.7L engine.
Do you have spark, everywhere? Did you use a gage And check fuel pressure, with tbi fuel injection 9--13 psi. With throttle body injection you should be able to see fuel injector/s spray pattern, both fuel injectors. Even if injector/s spray pattern looks good, 5 psi won't start and run a v8.
Check for applicable trouble codes. My info shows your obd1, so you should be able to check some codes, yourself, if there are any.
You need air--fuel--spark--compression, proper amount at the proper time and it should start.
Have you checked your fuel filter? It could be clogged. Has the truck sat for a long period of time? Is the fuel pump GM? Does it have enough fuel pressure? Are you sure it's not ignition related? Possibly an ignition module shorting out after it gets hot.
I wouldn't replace the injectors, especially not all 6 or 8. The problem is probably a lack of fuel or fuel pressure, or a dirty throttle body. The computer controls idle speed with the idle air control valve by limiting the amount of air entering the throttle body. If the body is dirty the air passages can be blocked. I would take another look at the throttle body and check the fuel pressure.
Fuel gets pressure from the pump, but if the injector or injectors don't "fire," the fuel won't pass. This can be tested with a noid light plugged into the injector harness. It's a good possibility that the ignition module is bad. It's located under the distibutor cap, or under coil packs on newer versions. Some parts stores can test modules for you.