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350TPI wont start unless one injector unplugged

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Old Oct 26, 2013 | 10:25 AM
  #1  
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350TPI wont start unless one injector unplugged

My 90 GTA won't start unless one injector is unplugged. I have good spark and hear the fuel pump priming. I checked for power at both terminals of the injector plugs. Both wires have power. I think there is a short somewhere. Anyone else have a problem like this?
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Old Oct 26, 2013 | 12:05 PM
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Re: 350TPI wont start unless one injector unplugged

Check that leads are on correct injectors; easy to misconnect.
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Old Oct 26, 2013 | 12:12 PM
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Re: 350TPI wont start unless one injector unplugged

it was running good the other day...parked it and won't fire up. the leads are in correct order.
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Old Oct 26, 2013 | 12:40 PM
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Re: 350TPI wont start unless one injector unplugged

ohm test injectors: pull plugs off injectors... then place leads from voltmeter on each side of the two prongs inside the injector. should be around 16ohms if stock.... southbayfuelinjectors.com/ on here is the go to for some nice replacements if needed.
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Old Oct 26, 2013 | 02:29 PM
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Re: 350TPI wont start unless one injector unplugged

Originally Posted by Mr.Bounge
My 90 GTA won't start unless one injector is unplugged. I have good spark and hear the fuel pump priming. I checked for power at both terminals of the injector plugs. Both wires have power. I think there is a short somewhere. Anyone else have a problem like this?
Does the engine start no matter which injector is unplugged?
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Old Oct 26, 2013 | 04:32 PM
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Re: 350TPI wont start unless one injector unplugged

Originally Posted by paulo57509
Does the engine start no matter which injector is unplugged?
Does not start when injector for #1 cylinder plugged in...it starts right up when its unplugged. Haven't checked injector resistance yet.
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Old Oct 26, 2013 | 05:16 PM
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Re: 350TPI wont start unless one injector unplugged

Originally Posted by Mr.Bounge
Does not start when injector for #1 cylinder plugged in...it starts right up when its unplugged.
So that injector must be faulty. if the ECM sees a bad injector it shuts down all the injectors in that bank

Originally Posted by James Sutton
Check that leads are on correct injectors; easy to misconnect.
And that effects what exactly ???????
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Old Oct 26, 2013 | 07:58 PM
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Re: 350TPI wont start unless one injector unplugged

Originally Posted by James Sutton
Check that leads are on correct injectors; easy to misconnect.
There is no specific order. Just bank 1 and 2, drivers side-passenger side.
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Old Oct 27, 2013 | 10:01 AM
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Re: 350TPI wont start unless one injector unplugged

Originally Posted by L98GTA87
There is no specific order. Just bank 1 and 2, drivers side-passenger side.
Not even then, there is only one injector driver in the ECM ('7730 in this case). It is batch fire.

Mr.Bounge, if these are still the original Multec injectors, just replace them. Don't bother to measure them, they are bad (the coils short out).

RBob.
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Old Oct 27, 2013 | 03:12 PM
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Re: 350TPI wont start unless one injector unplugged

My injectors were in the 16 ohm range, all of them. Replaced them with a set from SouthBay, all good. Don't even waste your time with those original injectors.
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Old Oct 28, 2013 | 12:06 PM
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Re: 350TPI wont start unless one injector unplugged

Have you hooked a scan tool to your car to do any diagnostics? Did you check that your coolant temp sensor is functioning properly? If the CTS is bad, the ECU will think it's -40* outside and will add way too much fuel at startup. Unplugging an injector may be offsetting that massive fuel enrichment enough to let the vehicle start.
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Old Oct 28, 2013 | 08:07 PM
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Re: 350TPI wont start unless one injector unplugged

Originally Posted by Jim85IROC
Have you hooked a scan tool to your car to do any diagnostics? Did you check that your coolant temp sensor is functioning properly? If the CTS is bad, the ECU will think it's -40* outside and will add way too much fuel at startup. Unplugging an injector may be offsetting that massive fuel enrichment enough to let the vehicle start.
Just measured resistance in each injector.....cyl#1 is 0.6ohms and cyl#7 is 8.0ohms. The rest are around the 16ohm mark. I noticed the engine missing the last couple of weeks. I replaced all the injectors 3 years ago with rebuilt delco ones. I guess that was a huge mistake.
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Old Oct 28, 2013 | 08:23 PM
  #13  
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Re: 350TPI wont start unless one injector unplugged

looking at injectors from south bay....price is $165.99 /8
is that the price for all 8 injectors or for each one. sorry if I sound confused, but I bought my delco rebuilts for $75 each
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Old Oct 28, 2013 | 08:31 PM
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Re: 350TPI wont start unless one injector unplugged

Yes, that is the price for a set of rebuilt Bosch III injectors.
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Old Oct 28, 2013 | 08:38 PM
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Re: 350TPI wont start unless one injector unplugged

Originally Posted by Mr.Bounge
looking at injectors from south bay....price is $165.99 /8
is that the price for all 8 injectors or for each one. sorry if I sound confused, but I bought my delco rebuilts for $75 each
Should be all (8).
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Old Oct 28, 2013 | 09:23 PM
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Re: 350TPI wont start unless one injector unplugged

As said above. Can't go wrong with them either. The warranty and support from SouthBay makes it worth while. Not to mention those injectors are great.
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Old Oct 28, 2013 | 09:28 PM
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Re: 350TPI wont start unless one injector unplugged

Originally Posted by L98GTA87
As said above. Can't go wrong with them either. The warranty and support from SouthBay makes it worth while. Not to mention those injectors are great.
I second that. I also replaced the fuel pressure regulator diaphragm while I had it apart, and bought the fuel pressure regulator diaphragm from SouthBay as they sell it as well.
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Old Oct 29, 2013 | 06:49 PM
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Re: 350TPI wont start unless one injector unplugged

Originally Posted by IROCgiraffe
I second that. I also replaced the fuel pressure regulator diaphragm while I had it apart, and bought the fuel pressure regulator diaphragm from SouthBay as they sell it as well.

Thank you everyone! Mr. Bounge, the cost is for the set of (8) injectors.
They come with a 3 year warranty, and yes they are $165.99 however tgo members receive a 10% discount using the promo code tg11
If you have any questions please give us a shout at the shop.

516-442-4707
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Old Oct 30, 2013 | 07:43 PM
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Re: 350TPI wont start unless one injector unplugged

something that I forgot to mention. when I unplug cylinder #1 injector, the engine starts. I used a needle nose pliers and grounded the terminals together and the engine stalls. does anyone have a clue whats going on?
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Old Oct 30, 2013 | 08:11 PM
  #20  
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Re: 350TPI wont start unless one injector unplugged

Yeah...the ECM is detecting the same type of fault, when you create a zero resistance connection across those two terminals, as your bad injector. Its shutting down the all of the injectors to protect itself.
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Old Oct 31, 2013 | 07:58 AM
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Re: 350TPI wont start unless one injector unplugged

Originally Posted by Mr.Bounge
something that I forgot to mention. when I unplug cylinder #1 injector, the engine starts. I used a needle nose pliers and grounded the terminals together and the engine stalls. does anyone have a clue whats going on?
Don't do that, the injector driver has been under enough stress due to the nearly shorted #1 injector as it is. By shorting +12 volts to the injector driver, that is trying to provide a ground to fire all of the injectors, you are stressing the heck out of the driver.

Contrary to popular belief there is no self-protection circuity in the ECM.

As I previously posted, just replace the injectors, they are bad. Even though they are not the original Multec injectors, there is no difference between having the originals in there or having re-man Multec injectors in there.

They fail by the coils shorting and going through a "re-man" process won't do a thing about that failure. It will happen, which it has on at least two of the "new" injectors.

RBob.
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