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350 tbi injector pulse prob.


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roger2791
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Sep 2, 2010, 10:09 PM

Post #1 of 35 (6635 views)
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350 tbi injector pulse prob. Sign In

91 chevy silverado 1500 2wd step side 350 tbi lost injector pulse turned truck off and it would not start afterwards.
all fuses good truck will start and run w/starting fulid but dies when you stop spraying.
i can force the pulse on the injector with a test light between the purple w/white stripe wire off of the ing.module and the pos.side post of batt. so i know the injectors are good and its an new module (inside the dis.)


Hammer Time
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Sep 2, 2010, 10:15 PM

Post #2 of 35 (6628 views)
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Re: 350 tbi injector pulse prob. [In reply to] Sign In

Are you losing the power side or the pulsing ground side?




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roger2791
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Sep 2, 2010, 10:23 PM

Post #3 of 35 (6624 views)
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i get power to the injector but will not pulse


Hammer Time
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Sep 2, 2010, 10:25 PM

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Does the check engine light come on for bulb check when the key is first turned on?




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roger2791
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Sep 2, 2010, 10:33 PM

Post #5 of 35 (6616 views)
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yes light dose come on i also have a code stored. using jumper wire flashes code 12.32


Hammer Time
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Sep 2, 2010, 10:36 PM

Post #6 of 35 (6612 views)
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Re: 350 tbi injector pulse prob. [In reply to] Sign In

That's an unrelated code. You could be looking at a bad ECM here but you need to first verify all the ECM grounds and the wiring to the injectors first.




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(This post was edited by Hammer Time on Sep 2, 2010, 10:37 PM)


roger2791
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Sep 2, 2010, 10:43 PM

Post #7 of 35 (6606 views)
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Re: 350 tbi injector pulse prob. [In reply to] Sign In

where do i get good wiring diag.


(This post was edited by roger2791 on Sep 2, 2010, 10:50 PM)


Sidom
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Sep 2, 2010, 11:20 PM

Post #8 of 35 (6602 views)
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Re: 350 tbi injector pulse prob. [In reply to] Sign In

Hmmmm..... This strange..... You are saying it's passing a "tap test".

I'm assuming you are using a noid light to check for pulse.....

You said the module is new...... The truck died and you just put a new module in it with the same results? or This module was new, already in the truck and it was running but now it died?






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roger2791
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Sep 3, 2010, 12:07 AM

Post #9 of 35 (6597 views)
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changed the module after truck died because i could make the injectors fire with test light jumping it between wires coming out of moudule (purple w/ white stripe) and pos. term. of the batt. so silly me i assumed it was a module problem.


(This post was edited by roger2791 on Sep 3, 2010, 12:08 AM)


roger2791
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Sep 3, 2010, 12:10 AM

Post #10 of 35 (6595 views)
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but i was told that this means the E.C.M is good. is this also a bad assaumtion?


Sidom
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Sep 3, 2010, 2:30 AM

Post #11 of 35 (6592 views)
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With you getting a SES, flashing a 12 and passing the tap test it sure looks like its working.... As far as getting 2 modules doing the same thing, that's kinda out there to....

There is a few reasons why the PCM would shut down the pulse......It's late & my mind just aint movin that quick so I'll have to check all the reasons later..... One reason for sure, is WOT or clear flood. If the comp "thinks" you have it floored it'll shut off the pulse. Try disconnecting the TPS & see what that does (besides setting a code..Sly). You said you have a 32. The is just an EGR code & while there is no ref voltage the PCM does ground it.... Just for the hellva it, disconnect the egr solenoid, it should be just to the right of the throttle body....

This is an exploded diagram of the PCM connecter......What is missing on this is just the injector wires going to the injectors & the injector power source.... The PCM use this signal along with some other inputs to determine the pulse width for the injectors (how much gas the engine needs)



Just for the heck of it......triple check all the fuses...........please


Another thought after looking at this diag a bit............. Double check all the connecters in the dist...... It really seems like the module isn't sending a signal out on ckt 430..... I'll have to ponder this some more.........it's late..........







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(This post was edited by Sidom on Sep 3, 2010, 2:35 AM)


roger2791
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Sep 3, 2010, 3:47 PM

Post #12 of 35 (6576 views)
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triple chk fuse and they are fine. today have noticed green wire off of the pick up coil going to the ing. module insalation is cracked and wire exsposed but if i had a problem with the pick up coil wouldnt i also have a problem with the spark (no signal to the (ext.) ing. coil resulting in no spark)


(This post was edited by roger2791 on Sep 3, 2010, 3:52 PM)


Sidom
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Sep 3, 2010, 10:52 PM

Post #13 of 35 (6567 views)
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You know the one thing I didn't think about is there is a ground coming from the PCM to the module. I don't think it's a pickup coil either or it wouldn't run on starting fluid.....

Unfortunately my database is down. but if all the wires are good, new module and it's still not getting a pulse then HT is probably right and you may have a bad PCM........ This is where it would be real nice to have a "known good" tester to pop in real quick.....

IF you can't get a diagram for this.....I'll see if I can bring on from the shop.........






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roger2791
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Sep 4, 2010, 12:56 AM

Post #14 of 35 (6563 views)
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you say a pcm? is this the same as ECM i didnt think this truck had a pcm its 91 but then again i dont know every thing or i would not be in this predicument. ha / ha. thanks for all your help its good to know that are still nice folks willing to help another when there down...


(This post was edited by roger2791 on Sep 4, 2010, 1:14 AM)


Sidom
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Sep 4, 2010, 1:23 AM

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Yea it's basically the same thing...... PCM, ECM, ECU are all acronyms for the engine computer... Manufacturers all have to use different terms for the same thing.

Like HT said, the powers and grounds have to be verified 1st before pulling the trigger on it. If you had one you could swap, I'd definitely try that, if not I would want to make sure there wasn't a bad wire 1st before buying one..........


I'll see if I can't find some diagrams for you or maybe HT has some he can post....

Just a footnote, GM has a bad habit of listing comp ground circuits as "low reference". It shouldn't be a problem for what you have to do, but when you are tracing ref voltage circuits it can really get confusing & misleading if you aren't aware of it...............






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(This post was edited by Sidom on Sep 4, 2010, 1:27 AM)


roger2791
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Sep 4, 2010, 2:08 AM

Post #16 of 35 (6553 views)
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thanx.


Hammer Time
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Sep 4, 2010, 7:57 AM

Post #17 of 35 (6546 views)
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Make sure this matches because there are some varying versions of this








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Sidom
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Sep 5, 2010, 2:02 PM

Post #18 of 35 (6531 views)
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Yea that's what I was thinking of HT.

Roger you can see the 12v & grounds on those pins. While it does run with carb clean it would still be a good idea to make sure there is no power or resistance problems on those and the 5v ref is good as well......

These are the connection you really want to make sure are good. 453 was the ground I forgot about going to the module. While you can get a pulse with the tap test. That means the pcm can generate a pulse, for what ever reason it's not getting a signal to generate a pulse (maybe?)..... These problems are a little tougher to check out with out a scope but not impossible... This is for your module. You can find the corresponding ckt numbers on HT diagram....








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roger2791
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Sep 5, 2010, 3:31 PM

Post #19 of 35 (6523 views)
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thanx im checking now and i will get back with the results.. am i to check the pins with the connectors on or off the ecm


(This post was edited by roger2791 on Sep 5, 2010, 4:37 PM)


roger2791
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Sep 5, 2010, 4:38 PM

Post #20 of 35 (6513 views)
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am i to check the pins with the connectors on or off the ecm


Sidom
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Sep 5, 2010, 5:32 PM

Post #21 of 35 (6506 views)
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I would 1st disconnect both ends of the connecters and check them with an ohm meter both for continuity and grounding. The system powers and grounds you can check with the connecters disconnect & KOEO. The signals & PCM grounds you are going to have to check with the connecters hooked up, KOEO & back probed.






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roger2791
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Sep 5, 2010, 6:30 PM

Post #22 of 35 (6498 views)
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all is right (12 volts & grounds) exept for b5 there is no ground and when you probe with test light looking for ground you here what sounds like the fuel pump priming the line. and a clicking of a relay switch.


Hammer Time
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Sep 5, 2010, 6:47 PM

Post #23 of 35 (6492 views)
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The fuel pump trigger should be a Dk green and and white on A1.
B5 is the EST reference signal on most and a speed sensor on one of them.




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roger2791
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Sep 5, 2010, 6:53 PM

Post #24 of 35 (6488 views)
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 should it have ground (b5)


Hammer Time
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Sep 5, 2010, 6:55 PM

Post #25 of 35 (6485 views)
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No. it's an ignition signal from a module. Don't be sending power down it. You have to be careful what your testing here.




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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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