98 Silverado 5.7, injectors not getting pulse?
#1
98 Silverado 5.7, injectors not getting pulse?
I have a 98 Silverado with 5.7, it was recently in an accident, but the only damages are the airbags popped and the plastic under the bumper got broke off, well when i finally got home to check it out the battery was dead, jumped it, it started fine, drove fine then i parked it, next day it fired once and hasn't started on its own since.
Here's what I've done and checked out: NEW fuel pump, filter, pressure regulator, crank sensor, ignition module. Fuel pressure reads 61 psi and holds. Has blue spark. And will start with starting fluid down TB. All fuses and relays are fine. I shouldn't have thrown parts at it, hoping for a quick fix. So whats left? Injectors or PCM?
Also, once when pulling fuses on it the truck started cranking over on its own, no key in ignition, keys were in my pocket, had to loosen battery cables to stop it, but hasn't done it since...
Here's what I've done and checked out: NEW fuel pump, filter, pressure regulator, crank sensor, ignition module. Fuel pressure reads 61 psi and holds. Has blue spark. And will start with starting fluid down TB. All fuses and relays are fine. I shouldn't have thrown parts at it, hoping for a quick fix. So whats left? Injectors or PCM?
Also, once when pulling fuses on it the truck started cranking over on its own, no key in ignition, keys were in my pocket, had to loosen battery cables to stop it, but hasn't done it since...
Last edited by Goose25; July 26th, 2012 at 10:14 AM.
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Ronnie post (October 27th, 2023)
#3
CF Monarch
If it stays running, the fuel system is draining back to the tank is a likley problem. What isn't clear to me if what oldchevy is asking, and what I am stating, if the fuel is draining back to tank, the fuel pump should pressurize the system with key on. Do you have a weak crank, as in low battery when trying to start?
#4
#5
If it stays running, the fuel system is draining back to the tank is a likley problem. What isn't clear to me if what oldchevy is asking, and what I am stating, if the fuel is draining back to tank, the fuel pump should pressurize the system with key on. Do you have a weak crank, as in low battery when trying to start?
#7
CF Monarch
Well, I'd say PCM since none of them are fireing. You could put a pick test light wihile cranking no lights not power. I don't have a 98 book, but 99 shows pcm controls the injectors. I've had a misfire issue with one injector on my 3.1, but it was just one.
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#8
Ever find the fix
I have a 2000 GMC K2500 with the same issue i have tried everything. It has spark cranks has 65psi fuel pressure, it is as if it has no fuel injector pulse. I can try to start it and then pull a plug and its dry. So its like its got no fuel but has 65psi at the testing port. Spark is blue and we have the battery on a constant charge. I have also tried 3 different ECUs all with the same engine and transmission out of the scrap yard.
#9
any dtc?
you need a crankshaft signal for injector pulse....monitor rpm data with a scan tool and crank the engine over. you should see approx. 200 when cranking...if you get zero rpm there is no crank signal to the pcm
you need a crankshaft signal for injector pulse....monitor rpm data with a scan tool and crank the engine over. you should see approx. 200 when cranking...if you get zero rpm there is no crank signal to the pcm
#10
Update. Borrowed a buddys autel scan tool comes up with 175-185 rpm when cranking. Still lost.
Last edited by David Cook; June 3rd, 2020 at 5:57 PM.