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1993 chey z-71 tbi issues

  
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1993 chey z-71 tbi issues

 
georgev georgev
I love my Chevy Chevette! | Posts: 3 | Joined: 04/13
Posted: 04/22/13
03:04 PM

what would cause the left bank of the tbi not to work???? other side works, while running i changed the leads and the left side pumped with right side wireing,put a test light on red wire and its hot,,,can anyone help please???  

waynep712222 waynep712222
V-6 Camaros rule! | Posts: 122 | Joined: 03/13
Posted: 04/22/13
07:15 PM

start with an OHM meter reading across the fuel injectors ... see if the OHMs reading match.. its probably 1.2 OHMs.. this is an important test...

you might want to check the computer grounds.. where they come out of the harness and attach either to the intake manifold or back of the heads..    that they are nice and clean.. tightly attached...


next.. check the connector at the computer. that is properly connected..  that the PINs have not pushed out or pulled out..

you might want to follow the wiring colors. and run an OHM meter test on the wiring..

lastly... its possible the ECM has died... or was damaged by a shorted out injector...

when injectors fail... they fail in a random short circuit once in a while...

WHAT???  this has kicked my buttttt a few times....  the injector will ohm close to what the other one should.. but as the power comes oh... the magnetic field pulls the windings inside slightly tighter together.. and it shorts out..

proving this requires a digital volt meter with an 10 AMP DC or larger rating... i have meters with 10 AMP dc.. 15 amp dc and 20 amp DC rating...

this is a 5 SECOND TEST ONLY...  FIVE SECONDS...  and requires some thinking for the set up... usually a fuel injector connector pigtail, banana plugs  and some battery clips.

red battery clip...   to the positive lead for the fuel injector pigtail...


negative battery clip .. to a banana plug,       banana plug to the negative wire for the fuel injector pigtail...


set up...  meter to 10, 15 or 20 AMP DC setting..

banana plugs in the proper locations...  this on all meters is different than normal volts or ohm testing.. common is the same. the 10 amp is in a different port....


hook up the injector...   hook up the positive battery clip to the positive...    when ready... while looking at the meter... touch the negative battery clip to ground... watch the amp displayed..  this is a 5 second test...   you will have to do BOTH injectors one at a time... and compare....

why 5 seconds... if you do more... you will BURN Out the INJECTOR windings...



you can see the injectors all the way to the top right of this diagram... pins D14 and D16...

the injector pulls them to ground  to pulse them...   you can see the grounds on pins A12 and D1   its totally possible that one injector is grounded with one wire and a different ground for the other..

so far i have not made you spend a BUNCH of money.. you can do the amp test if the injectors read differently with the OHM test...

its quite possible that the ECM has failed... there are several different versions.. and pay the CORE... and keep it until you have gotten the truck running..   don't forget that there is a CHIP that needs to be removed and installed by YOU from the old one to the new one with extreme care... that you get all the pins into the socket..

1990Chevytruckenginecontroltbi Zps801c7a6e  

waynep712222 waynep712222
V-6 Camaros rule! | Posts: 122 | Joined: 03/13
Posted: 04/22/13
07:20 PM

you will have to SLIDE the image above to the right to see the injectors..  or print it out..

lastly... if you are good at soldering... you might want to carefully open the ECM with it disconnected...  and holding onto a corner of it so you don't create static charge that will blow it out... and examine it for bad solder joints...

the injectors are HIGH AMP draw circuits and i have found more than one computer with damaged solder joints..

this is a honda relay... but the solder joints look similar...

check the connector to the circuit board...

follow the traces to the power transistors or what ever they are ... probably mounted to a side heat sink...


Hondamainrelaycircuitboard  

georgev georgev
I love my Chevy Chevette! | Posts: 3 | Joined: 04/13
Posted: 04/24/13
12:58 PM

ha got it it was blue wire going into harness not getting contact thanks so much you were very helpful thanks to super chevy too for site