TBI Throttle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.

Testing TBI Injectors

Old Oct 6, 2003 | 01:36 PM
  #1  
chevypower's Avatar
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From: Panama City, Fl
Car: '89 Formula, '97 Z28, '88 Formula 350
Engine: 305 TBI(LO3)
Transmission: TH700R4(MD8)
Testing TBI Injectors

Is it possable to test the injectors? And how if you can? My drivers side injector has quit spraying fuel. I've hooked a nod light to the wire connector and it flashes, so its getting power. I just rebuild the whole TBI unit about a month back and did the ultiment TBI mods, I didn't install new injectors though. Can you straghit wire the injector and hear it running?
Also what injectors are the same? A new one is $64.95. He11 Turbo City has matched injectors for $69 each. Wonder if I could mail them my good injector and they could find me a matched one for it, that would be worth the extra $5 + shipping. I think I read the 4.3L and 5.0L has the same injectors, then the 5.7L has two, one for police cars and one for normal cars. Then the 454ci has a different one. Is this true. I've been in the junk yards alot here lately, and there is no 305 TBI Camaros here. But a lot of 4.3 TBI trucks & vans. Please help, Bobby
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Old Oct 6, 2003 | 02:38 PM
  #2  
nick harmon's Avatar
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From: institute, wv
Car: 91 RS
Engine: LO3
Transmission: T-5
i just bought 350 injectors (supposedly off of a police car) from a bone yard for $50. installed them, turned the key, and.... nothing.
since you know one isnt working go ahead and take the other one out too. get a bowl fill it with carb cleaner and let both injectors soak for a couple hours, it wont hurt them. then take the one that stoped spraying and give it a few firm taps with the handle of a screwdriver (plastic!) worked for me cause niether one of my injectors were working. it may not spray properly at first, give it time. run the engine at different rpms, cracking it wot a few times then if it is good it should loosen up within a few minutes and start operating normally. this is the exact proccess i went through on mine, niether of mine would even make a sound, then i did the steps listed above and viola, she started purrin like a kitten again. wish it wasnt a kitten though!
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Old Oct 7, 2003 | 09:31 AM
  #3  
chevypower's Avatar
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From: Panama City, Fl
Car: '89 Formula, '97 Z28, '88 Formula 350
Engine: 305 TBI(LO3)
Transmission: TH700R4(MD8)
Like I said I had just rebuild the TB, they had soked in a carb vat fot two days. The injector hasn't worked since the rebuild.
Hey Nick could you hear your injector running? I'm just wanting to know if there the same size as 4.3L injectors, I can get one of them for free!
By the way Nick did you put your 350 "police" injectors in a 305? If so how did it run? Have you did the APR mod to adjust the pressure for them? I'd thought about that, but other people had talked me out of it. Thanks, Bobby
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Old Oct 7, 2003 | 10:22 AM
  #4  
nick harmon's Avatar
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From: institute, wv
Car: 91 RS
Engine: LO3
Transmission: T-5
no, i could not hear them running-at first. no, i dont have the afpr mod. and yes, my car runs pretty sh!#$y with the 350 injectors. it runs smooth and all, but WOT blows the big one. P-T feels good though. but they came with the fuel metering assembly so i thought, "im gonna need them anyway with my future mods."
so unless your gonna do or have done the AFPR, or burn a chip, dont get the 350 injectors! i think 4.3 and 5.0 injectors are the same. if im wrong someone will catch it by the end of the day.

Last edited by nick harmon; Oct 7, 2003 at 10:28 AM.
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Old Oct 7, 2003 | 10:41 AM
  #5  
nick harmon's Avatar
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From: institute, wv
Car: 91 RS
Engine: LO3
Transmission: T-5
oops, i see you do have a FPR. so its really your call. i hear that AFPR are really a crutch for chip burning. with a properly tuned chip i dont think you need an AFPR. thats what i hear.... i think. i read so much on here that it all gets jumbled up to the point where im scared to even comment.
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Old Oct 7, 2003 | 01:14 PM
  #6  
chevypower's Avatar
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From: Panama City, Fl
Car: '89 Formula, '97 Z28, '88 Formula 350
Engine: 305 TBI(LO3)
Transmission: TH700R4(MD8)
Proper chip tuning is a must! I let http://www.pcmforless.com handle all mine. http://www.tbichips.com burns them for $30-$50 don't think they are real performers, but $30 for the speed limator removed is a deal though. It beats the switch where your speedo shuts off. See Ya, Bobby
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Old Jun 20, 2015 | 02:56 AM
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Re: Testing TBI Injectors

You can test the injectors by connecting them to a 9 volt battery and pulse it on the off. If the injectors work you should hear them click open and close.
They can be cleaned by removing the filter screen and spray brake cleaner into the injector inlet while pulsing the battery to fire the injector. Just make sure all the excess brake cleaner is wiped off the injector before putting the filter and O ring back on as they might get damaged.
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Old Jun 25, 2015 | 11:02 PM
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Re: Testing TBI Injectors

Originally Posted by NZKnight
You can test the injectors by connecting them to a 9 volt battery and pulse it on the off. If the injectors work you should hear them click open and close.
They can be cleaned by removing the filter screen and spray brake cleaner into the injector inlet while pulsing the battery to fire the injector. Just make sure all the excess brake cleaner is wiped off the injector before putting the filter and O ring back on as they might get damaged.
I got a ? On Tbi injectors should all 4 wires test 12v and wat if it doesn't pulse just constant power
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Old Jun 27, 2015 | 03:36 AM
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Re: Testing TBI Injectors

Originally Posted by Unforgiven2033
I got a ? On Tbi injectors should all 4 wires test 12v and wat if it doesn't pulse just constant power
The injectors are controlled by the ECM on the ground side. Therefore, all four wires will show power. The ignition switch supplies power in "crank" and "run". When the computer connects the ground side of the circuit to ground, the injector fires. As the engine runs and the injectors are activated by the ECM, you'll see power on the supply side of the injector, and pulsing/reduced (or no) voltage on the ground side.
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Old Jun 27, 2015 | 09:45 PM
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Re: Testing TBI Injectors

My problem is I have 12v to all wires except the blue one noid light shows nothing new fuel pump new ecm with new prom new fuses and relays new distributor but still no pulse.... Vats?.... There is a yellow wire coming down from ignition that has 2 white wires in it wat is the voltage suppose to be to these if that could be the problem
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Old Jun 28, 2015 | 12:34 AM
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Re: Testing TBI Injectors

Originally Posted by Unforgiven2033
My problem is I have 12v to all wires except the blue one noid light shows nothing new fuel pump new ecm with new prom new fuses and relays new distributor but still no pulse.... Vats?.... There is a yellow wire coming down from ignition that has 2 white wires in it wat is the voltage suppose to be to these if that could be the problem
Punctuation and proper sentence structure would be a big plus.

If you have power to both sides of the injector, you have no ground. NORMAL when the ECM isn't supplying the ground.

I thought VATS would allow the engine to start, then die after some short amount of time--a few seconds, perhaps. Maybe I'm wrong.
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