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88 S10 Injector won't pulse
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64Chevy
User
Aug 18, 2009, 10:42 PM
Post #1 of 11
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88 S10 Injector won't pulse
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I have an 88 S10 truck. The motor cranks over but will not start. I can pour gas into the throttle body and the it will start flutter and die. I watch the injector and it does not spray. It does have fuel pressure to the injector. I have switched the throttle body out with one from another vehicle. Have checked the ECM fuses both are ok. I switched the computer to another truck and it was ok. Any ideas on what to check next?
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 18, 2009, 11:27 PM
Post #2 of 11
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Re: 88 S10 Injector won't pulse
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Test to see if you have power at one side of the injector plug with the key on.
Do you?
Does your check engine light come on when the key is on?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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64Chevy
User
Aug 19, 2009, 7:04 AM
Post #3 of 11
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Re: 88 S10 Injector won't pulse
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With the wire unhooked from the injector it has 12v accross the plug, but with it plugged in the ground drops out but still has the 12v. When the key is turned on it does have a check engine light and it does not go off.
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 19, 2009, 7:56 AM
Post #4 of 11
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Re: 88 S10 Injector won't pulse
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Things are pointing to a bad ECM but before you can condemn the ECM, you have to verify all the power supplies and grounds coming into it.
If you need a pinout chart for the ECM plug, I'll need the engine size.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Sidom
Veteran
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Aug 19, 2009, 1:59 PM
Post #5 of 11
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Re: 88 S10 Injector won't pulse
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An engine size would be helpful.. On some of those the PCM uses a reference for the injectors from the ICM (control module). Don't see it a lot but I've had a few bad modules with spark & no injector pulse.........
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64Chevy
User
Aug 19, 2009, 9:56 PM
Post #6 of 11
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Re: 88 S10 Injector won't pulse
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it's a 2.5 4 cylinder, 5-speed. I put the computer in another truck and it ran fine.
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64Chevy
User
Aug 31, 2009, 12:00 AM
Post #7 of 11
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Re: 88 S10 Injector won't pulse
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I replaced the ICM in the distributor. But I still have no injector pulse. Could it possibly be the hall effect switch?
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DanD
Veteran
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Aug 31, 2009, 4:11 AM
Post #9 of 11
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Re: 88 S10 Injector won't pulse
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Check the TPS (throttle position sensor); signal return; if it’s above 4 volts, the PCM will go into clear flood mode and turn off injector pulse.
I would also check this right at the PCM connector; just incase the signal return wire has shorted to power.
At the PCM, its circuit #417, connector C, terminal 13, a dark blue wire. With ignition on and the throttle closed; there should be approx .5 (1/2) volt.
Dan.
Canadian "EH"
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64Chevy
User
Aug 31, 2009, 4:16 AM
Post #10 of 11
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Re: 88 S10 Injector won't pulse
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Any other ideas? I used a tried the computer in another truck, worked fine. I replaced the Ignition module no help. There is switched 12v power on the red lead. I jumpered the blue wire from the computer to the injector still no spray. Is there any tests that I can do to check out the inputs? Is there a spot to check the actual fuel pressure? I am lost!
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DanD
Veteran
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Aug 31, 2009, 6:27 AM
Post #11 of 11
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Re: 88 S10 Injector won't pulse
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I just gave you a test to perform on the TPS input to the PCM?
On a lot of the older TBI systems, there wasn’t a test port to attach a fuel pressure gauge. I use to be able to buy an after market fuel filter that had a test port incorporated into it. If there wasn’t one available; I would remove the filter and install my own test line in its place that had a shadier valve spigot that I could connect my gauge too.
Dan.
Canadian "EH"
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