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350 tbi injector pulse prob.


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Sidom
Veteran / Moderator
Sidom profile image

Sep 5, 2010, 4:00 PM

Post #26 of 35 (3559 views)
Re: 350 tbi injector pulse prob. Sign In

The only thing you are going to want to use a test light for is checking the source voltage and source grounds with the connecters disconnected. This basically is loading the circuits and making sure there isn't any resistance problems.

Once the connecters are hooked up you need to be using a scope or multimeter. A test light is a load devise and shouldn't be used on a low voltage comp circuit due to the fact it could allow too much current flow. A multimeter is harder because if you are looking for a wave form or duty cycle, on a good circuit you will just see rapidly fluctuating readings on the meter that don't really stay at one spot. A scope, you can see the whole pattern, amplitude, time any pattern break down etc.

I realize most people don't have a scope at home due to the expense. So at some point you get limited...Once you get to the point where all the wires have continuiity, aren't shorting to ground or power anywhere, good ecm power & grounds, that is where you need to be able to verify the ecm inputs & outputs.

It really sounds like at this point you've covered all the bases.... I'm just trying to make sure there isn't something I forgot....... Most of the time on these older ones that lost pulse that pasted a tap test it was a bad module.......You said you changed that & really can't see getting a new module doing the exact same thing...

I hate gambling but your almost to the point of running out of tests to do with the equipment you have...


roger2791
User

Sep 5, 2010, 5:33 PM

Post #27 of 35 (3550 views)
Re: 350 tbi injector pulse prob. Sign In

the white and green wires coming off the pick up coil inside the dis. is it possable for a weak signal that would allow spark but not injector ref. signal. and if so what should the voltage be /or how do you test


Sidom
Veteran / Moderator
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Sep 5, 2010, 6:46 PM

Post #28 of 35 (3545 views)
Re: 350 tbi injector pulse prob. Sign In

If you can get to run, then more than likely the pickup coil is good. It produces an a/c pattern you would need to check with a scope, plus with all the connections being in the dist, it's hard to do. There may be some grounds in the dist housing that have got corroded. It the housing is corroded inside, take apart what you can & clean it real good.....


roger2791
User

Sep 5, 2010, 9:00 PM

Post #29 of 35 (3539 views)
Re: 350 tbi injector pulse prob. Sign In

dist. looks good cleaned it off good when i replaced the module..


Sidom
Veteran / Moderator
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Sep 6, 2010, 10:31 AM

Post #30 of 35 (3524 views)
Re: 350 tbi injector pulse prob. Sign In

Just one quick question. What did you use to check for pulse and did you disconnect both injectors when checking for pulse?

I noticed your other post, if you have a good tester to use that would definitely be the way to go...


roger2791
User

Sep 7, 2010, 8:12 AM

Post #31 of 35 (3512 views)
Re: 350 tbi injector pulse prob. Sign In

used a test light to check for pulse on the injector one at a time changed the ecm (moved the prom chipfrom mine to the tester ecm) still no pulse at this point only one thing left to change distributer. have a theroy if the pickup coil is sending a weak signal is it possable to have a weak signal going to the ing coil causing a weak spark enogh to ignite the starting fluid but not a strong enough signal going to the computer for a pulse to be generated? ... (the signal coming from the module to the coil is stepped up to casue a spark) right???


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 7, 2010, 8:42 AM

Post #32 of 35 (3507 views)
Re: 350 tbi injector pulse prob. Sign In

That's the best way I know to trash your computer. I hope your aware that it's the ground side that pulses, not the power.
This has to be tested using a noid light.





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

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.



roger2791
User

Sep 7, 2010, 2:14 PM

Post #33 of 35 (3500 views)
Re: 350 tbi injector pulse prob. Sign In

thanx HT you do give very good advise. yes i did know the ground side is the one that pulsed.
i did find the problem and it was my error. last night I put a spark tester on the coil wire after changing the ECM.
(I wanted to make sure that i was still getting sprak) and i noticed a very weak spark .
the spark was enough to ingnite the ether in the starting fluid but not strong enough to get the signal to the injector ??? have never seen this before but i assumed that since it would start w/ stating fluid that the spark was fine .I over looked the basics and thats when you really get lost...
At first i thought i had a problem no one had every seen before. but now I know that my problem was a very common
one. ASSUMING and/not RECHECKING THE BASICS. (always check and recheck the basics)... ha/ha.
thanx again for all of the help and feedback.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 7, 2010, 3:41 PM

Post #34 of 35 (3497 views)
Re: 350 tbi injector pulse prob. Sign In

What was it, bad coil?



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

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.



roger2791
User

Sep 7, 2010, 7:07 PM

Post #35 of 35 (3492 views)
Re: 350 tbi injector pulse prob. Sign In

pick up coil inside the dist.






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