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1995 suburban,5.7 Tbi


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bubba19621962
Novice

Apr 6, 2017, 5:22 PM

Post #1 of 14 (294 views)
  post locked   1995 suburban,5.7 Tbi  

doesnt have injector pulse when hooked up to a noid light,hot wire has juice when switch is on but shows no pulse on noid light,,wont light up.tried new ecm ,no change,tried ign module,no change,tried puting test light hooked to battery and grounded out to injector ground and it goes off and on but wont work with noid light,,any suggestions? please help if youve seen this before,,thanks


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 6, 2017, 7:25 PM

Post #2 of 14 (281 views)
  post locked   Re: 1995 suburban,5.7 Tbi  

Do you have spark?
Does the check engine light come on for bulb check when the key is turned 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.



bubba19621962
Novice

Apr 7, 2017, 11:03 AM

Post #3 of 14 (260 views)
  post locked   Re: 1995 suburban,5.7 Tbi  

hey thanks for the reply,,,yes i have spark,,i also have check engine light come on for bulb check....heres what ive done so far.
replaced fuel pump----new fuel filter----new ign module in dist---checked for spark and whether it breaks like points type ign does and it does that,,,when i checked the injector pulse with a noid light it doesnt flash like it should---one injector has juise when ign is turned on and the other is supposed to be ground that ecm works,,,hooked test light to battery and then to ground wire for injector,,it flashes when i turn over ign...could i possiby have a ecm ground problem? i also went and got new ecm and checked it and still the same,,thank god i know the guy at parts store,he let me return for refund. i worked for ford for 8 yrs and never seen anything like this in our shop and this thing has me stumped


bubba19621962
Novice

Apr 7, 2017, 11:12 AM

Post #4 of 14 (254 views)
  post locked   Re: 1995 suburban,5.7 Tbi  

one other thing about this,,when i grounded a and b on the aldl connector(it has the old obd 1 system) it wont flash a code 12 that tells me i accesed the ecm..it flashes 1 then 2 then a real quick third flash like its trying to flash a code 13,,but thats an o2 sensor code.


Hammer Time
Ultimate Carjunky / Moderator
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Apr 7, 2017, 11:12 AM

Post #5 of 14 (254 views)
  post locked   Re: 1995 suburban,5.7 Tbi  


Quote
one injector has juise when ign is turned on and the other is supposed to be ground that ecm works,


I don't know what you're trying to say here.

BOTH injectors should receive constant power with the key on and BOTH injectors should receive pulsing ground when the engine is cranking.

You should NEVER use a test light to test that pulsing ground and you can burn out your computer. Noid light only.

You could have a shorted injector so test for pulse with both injectors unplugged. You could also take a resistance reading on both injectors.

You say you tried a new computer. Did you swap the PROM when you did that?



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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.



kev2
Veteran
kev2 profile image

Apr 7, 2017, 11:59 AM

Post #6 of 14 (248 views)
  post locked   Re: 1995 suburban,5.7 Tbi  

trying to get the picture - This is a TBI just 2 injectors ? or CPI spider ? this is @switch year.
No lights on - security or CEL?
no remote starter or added alarm?
Jumping ALDL no codes flash - try test lamp A-B did tester flash?
You have spark several plugs? your are testing inj wiring at several cylinders?


Check CKP/pick up coil in dist.


(This post was edited by kev2 on Apr 7, 2017, 12:19 PM)


bubba19621962
Novice

Apr 7, 2017, 1:22 PM

Post #7 of 14 (243 views)
  post locked   Re: 1995 suburban,5.7 Tbi  

yep,tbi 2 injector,,i did change prom in computer,it had an after market hypertek chip on it and i took it off and put original prom in it..my original pluged in to the side of the hypertek chip then the hypertek plugged into prom connector in computer,it was already there when i pulled computer out,,nothing that i added.no security or cel lightno remote start or alarm addedive been reading some of your previous posts on 5.7 tbi problems from all the way back to 2012 i think it was,,ill be checking by what you say to check and ill do this process so i know i havnt missed anything,,it seems to me you know what youre talking about and ill foller the advice to a t,,lol
ill let you know what i find this weekend when it gets a little warmer outside..and yes it spark at all plug wires on dist cap,,no codes except the way i was saying flash once then twice,then a real quick third flash (duration of flash is shorter than first two) that puzzles me like i may have a bad ground..are all chevy tbi from 88 to 95 basically the same on the chevy engines?if so i saw couple posts from you that tells me about tps testing that tells me if ecm is going into flood mode and cutting of pulse to injectors the voltage that it should be showing and such,,,thanks hammer,,ill be back


bubba19621962
Novice

Apr 7, 2017, 1:27 PM

Post #8 of 14 (241 views)
  post locked   Re: 1995 suburban,5.7 Tbi  

i forgot to say,,i checked injectors with one still plugged up at the time, and i do have 12 volts constant on one wire on each injector i;;ll check them again your way ..i did check them by testing with a 9 volt battery and they click when touched..thanks again hammer


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 7, 2017, 1:44 PM

Post #9 of 14 (237 views)
  post locked   Re: 1995 suburban,5.7 Tbi  

Unplug both at the same time to use noid light just in case one is shorted.
Make sure the 12V remains when cranking also.

You also want to check all the ground wires in the car. If there is a computer ground disconnected somewhere, it will act like that.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



bubba19621962
Novice

Apr 8, 2017, 2:06 PM

Post #10 of 14 (218 views)
  post locked   Re: 1995 suburban,5.7 Tbi  

hey there hammer,i found that the 12 volt power drops when trying to crank the engine.it drops off to zero on test meter when i crank the engine.theres where my problem lies,,,,faulty ign switch or relay gone bad,,relay kicks off as long as im cranking hen kicks on when i go to power on switch only


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 8, 2017, 2:12 PM

Post #11 of 14 (208 views)
  post locked   Re: 1995 suburban,5.7 Tbi  

That power comes directly from the ECM1 fuse. Check that out.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



kev2
Veteran
kev2 profile image

Apr 8, 2017, 2:15 PM

Post #12 of 14 (206 views)
  post locked   Re: 1995 suburban,5.7 Tbi  

wiring ign switch powers ECM 1 inj circuit

link deleted .................. had nothing but host site main page


http://www.revbase.com/...wnloadPdf?id=1010992


(This post was edited by Hammer Time on Apr 8, 2017, 6:38 PM)


bubba19621962
Novice

Apr 8, 2017, 3:01 PM

Post #13 of 14 (198 views)
  post locked   Re: 1995 suburban,5.7 Tbi  

thanks hammer,,youre my hero lol...i found the problem in the relay fuse center under the hood,,this thing had a ton of corrosion on it..took a bit to figure it out but i dont think i wouldve found it that fast without your help..the corrosion was underneath where i couldnt see it....if ya ever make it to erwin tn i owe ya a steak dinner.thanks again and have a great weekend


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 8, 2017, 6:34 PM

Post #14 of 14 (188 views)
  post locked   Re: 1995 suburban,5.7 Tbi  

Glad everything worked out.

I'll close this now as solved.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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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