fpcam

Have a 1991 Camaro 5.0L engine.

Fuel is going to the throttle body. Not spraying from the injectors.

Checked the ohms on the injectors. Repair book says ohms should be 11-14.
My injectors read short, 0 ohms.

Are the injectors bad? Should I do further checks?

All fuses are good.

CamaroRider

Is this a TBI or TPI system?

Did you have the measuring instrument set to the correct setting to measure this low resistance and did you calibrate the ohm meter at this setting?

fpcam

Digital ohm volt/meter, 2kOhm setting, no calibration.

TBI system

CamaroRider

Normally an ohm meter can be set to a range of about 10 ohm, 100 ohms, etc. Then you would touch the probes together and spin the 'set' or 'calibrate' or (whatever dial) until you read zero ohms. Then you take the measurements through the probes. On my TBI injectors the ohm reading should be down near 1 or 1.5 ohms I believe. That is VERY low so you have to make sure you meter is set up to read that low.

CamaroRider

Actually, I just tried reading mine again. I had to set the ohm meter to the 1X scale, calibrate, then touch the injector leads. It showed just a hair over 1 ohm for each of them. My 10X scale just showed ZERO ohms. So you can see how critical it is to have the meter set for maximum sensitivity and calibrated.

fpcam

you have 1-1.5 ohms? Book states 11-14ohms. Did read further, relates to multiport injectors.

Do you know what the ohms should read if the injectors are defective?

fpcam

Thanks for the input. My meter is for high ohm resistance checks.

However, I am having a hard time figuring out why the injectors are not spraying.

CamaroRider

I have two injectors. Throttle Body Injection system. The resistance is expected to be 1 to 1.5 ohms.

were you able to set your meter to 1X, calibrate, then read the resistance across one the injectors ?
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I would find it somewhat improbable that all injectors would go bad at the same time. Now another big contributor to NO SPRAY would be a blocked fuel filter, blocked fuel lines, a fuel pump that is not running or a fuel feed system in the tank that leaks (such as a deteriorated hose connection between the fuel pump motor and the hard line inside the fuel tank). Another possible problem is that the fuel injectors are not being told to fire by the ECM.

fpcam

All of your reccomdations were excellent. I have already fixed the fuel pump, replaced the fuel filter, and determined that the fuel is reaching the throttle body. Took off the fuel pressure regulator, and turned the key, and watched the fuel geyser in the throttle body.(lol) Was hoping there was a simple test of the injectors to insure they were ok. Also replaced the ignition module.

Plan to rebuild the fuel pressure regulator then go to the electrical checks.

Thanks again for your suggestions.

CamaroRider

My engine was unused for 1.5 years and did not spray fuel into the engine. So I had to learn allot about the injectors and and firing them.

I removed my injectors and set a variable power supply. On this power supply I set the maximum current allowed to 1 AMP. I set the voltage to 6 VOLTS. When I placed the leads across the injectors I could hear them 'click'. I placed them in carburetor cleaner and 'cycled' them many times and also clicked them open and forced carburetor cleaner through them in reverse. This seemed to help them function and gave me proof I needed that they were indeed opening.

Now if your injectors are indeed functional, you do have adequate fuel pressure and they are still not spraying fuel then I would suspect that they are not being told to 'fire' by the ECM. If this is your situation then use the 'Search this Forum' tool in each forum to read prior posts. Use key words like 'injectors' 'no spray' or whatever. There are quite a few that discussed what should be checked. If I find some I will place some links here.

TurbomanKnight

Unplug the injector harness and put a noid light or a test light to check for injector pulse. If there is none, it can be caused by a VATS issue or a bad ignition module, among other things.

89IROCZ28

iTrader: (14)

As the engine is turned over you shuld be able to hear or feel the injectors 'clicking' when fired by the ECM. If you do, the problem is probably not w/ the injectors or ECM.

I think you're on the right track w/ rebuilding the fuel pressure regulator. A failed regulator diaphram is a common problem. If the diaphram in the regulator has failed, the pump can supply all the fuel the engine can handle, but nothing will come out of the injectors due to the lack of pressure. All the fuel will be routed back to the tank by the regulator.

fpcam

Finished replacing the fuel pressure regulator diaphragm. Reinstalled it and no difference. The car cranks, but no spray from injectors.

Messe with my key, now security light comes on and no crank.

Does anyone know how to disable the VAT in order to allow me to eliminate that from the electrical troubleshooting?
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There is no pulse coming to the injectors. The ignition module has been replaced. Would like to know how to disable the VAT to eliminate it from the trouble shooting process.

CamaroRider

Here is a link to some VATS information:

https://www.thirdgen.org/vats_passkey_system

Interesting read. Note how after unsuccessful attempts to start the engine it will lock out the user for some period of time before it will allow another start attempt. Also note the dash light. It could tell you something about the status of the VATS.

But I do not know enough about it to help you eliminate it.

fpcam

Excellent article!

Thanks.

Back to cranking and no start.

No spray from injectors.

Note: all mechanical problems relating to fuel have been fixed. On to electrical checks.

fpcam

Jumpered each injector to ground and +12v, each one clicked.

Put the key in the ignition...VAROOOM.

Car sarted and is still running.

Thank you CamaroRider.