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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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Chevy blazer: how do I test central sfi unit on 2000 blazer

Customer Question

how do I test central sfi unit on 2000 blazer with 4.3lv6 cranks no start will fire with starting fluid 63psi fuel pressure
Submitted: 1 year ago.
Category: Chevy
Expert:  Roy replied 1 year ago.
good afternoon my name is ***** ***** I will assist you have good fuel pressure. check the connector at the top of the spider unit for good, tight clean connections. it is possible the spider is the failure but tesing needs to be done to be sure. the other possibility is the pcm but it does run with spray. do you have a scan tool that can read information??? Roy
Customer: replied 1 year ago.
I have a matco scan tool. the connection is clean
Expert:  Roy replied 1 year ago.
ok, can you read if has an injector pulse while cranking? it should be in live information. Roy
Expert:  Roy replied 1 year ago.
ok, can you read live data?? Roy
Customer: replied 1 year ago.
fuelsys1 and 2 both show OL no change when cranking
Customer: replied 1 year ago.
no dtc's
Expert:  Roy replied 1 year ago.
no, thats open loop. that will change when the engine starts and runs for a couple of minutes. injector pulse width?? can you give me that reading?? Roy
Customer: replied 1 year ago.
ltft and stft read 0
Expert:  Roy replied 1 year ago.
thats normal with the motor not running what about what I asked??
Expert:  Roy replied 1 year ago.
how are you making out?? Roy
Customer: replied 1 year ago.
scanner does not show pulse width option
Expert:  Roy replied 1 year ago.
ok, then you may have to remove the spider assembly and hook it up outside the upper intake to see if the injectors are firing. Roy

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