Lost

[steveo]

a 1991 camaro rs didn't come from the factory with a black security box with a light.

you likely have an aftermarket alarm system.

maybe some idiot wired up a fuel pump disable with it.

i'd get that aftermarket alarm out of there, every single car i've ever owned that has one has been a huge source of problems.

[Crystalvictoriamail]

​My name is crystal and I love love Camaros can I say lol I live in ms and a friend referred me to this site because I'm at a stand still I recently got a 91 Camaro rs v8 tbi for Christmas only under the impression that it was a fuel pump and I replaced fuel assembly fuel pump fuel tank also n now the thing is is its a PROJECT having an issue w no power to gray fuel pump wire could anyone help please!

How how many volts r supposed to be going to the injectors

[steveo]

on your injectors, there's a power wire, and a switch wire.

the power wire is constant ignition voltage, fed by the ignition switch. you check the power wire against GROUND.with key on and engine not running. it should be within a volt of battery voltage, but more importantly, it should be fairly close to whatever the ignition +12v @ the ecm is so the injector offsets work correctly.

the switch wire simply connects and disconnects the ground, and is fed by the ecm. you can't really measure that signal in a meaningful way without an oscilloscope

[Crystalvictoriamail]

​My name is crystal and I love love Camaros can I say lol I live in ms and a friend referred me to this site because I'm at a stand still I recently got a 91 Camaro rs v8 tbi for Christmas only under the impression that it was a fuel pump and I replaced fuel assembly fuel pump fuel tank also n now the thing is is its a PROJECT having an issue w no power to gray fuel pump wire could anyone help please!

K so got the right voltage new tank fuel pump n regulator assembly the whole nine yards and defiantly know there's fuel coming to the top plate but it's not coming outa the injectors

[EagleMark]

You may have a VATS issue? If key does not have correct resistor to match VATS module then no pulse to fuel injector.

The injectors also need a DRP Distributor Reference Pulse to fire injectors. Sometimes you can tell when there is no spark at plugs. But other times the EST module in distributor will still produce spark at plug, but no fuel pulse at injector. The EST is a very finicky part when it comes to failing or being faulty and it's very rare for them to go bad, but they do.

Some auto parts stores are set to test this EST module. If you find one and take it out to test ask them to run the test three times. The module will get hotter with each test. If it fails any part of any test? Replace it with a AC/Delco brand. Aftermarket EST modules are just not as good!

Also check your grounds! Should be two from EFI system to engine, one on intake and one on back of head IIRC on Camaro. Clean, rust free, no loose wire, no paint underneath. As stated earlier the injector has power to it, the ECM grounds it to pulse/fire. Grounds are always an issue with EFI. They have to be perfect.

[Crystalvictoriamail]

K so got the right voltage new tank fuel pump n regulator assembly the whole nine yards and defiantly know there's fuel coming to the top plate but it's not coming outa the injectors

Alright might might sound crazy but nope no vats issue I know this n I have a pulse n also I have good grounds throw em at me any ideas cause I'm telling ya I did it all idk anymore! Oh and any one got directions how to take the actual injector apart let me know

[jim_in_dorris]

Crystal, go to an Autoparts store and rent a NOID light. Plug it into one of your injector connectors. Crank the engine. Does the light blink Yes/No

[Crystalvictoriamail]

K I have no pulse to the injectors what could I do?

[Crystalvictoriamail]

Crystal, go to an Autoparts store and rent a NOID light. Plug it into one of your injector connectors. Crank the engine. Does the light blink Yes/No

When keys keys turns over light comes on but when u crank no pulse also when I manually ground it it shoots fuel

[EagleMark]

Alright might might sound crazy but nope no vats issue I know this n I have a pulse n also I have good grounds

Crystal, go to an Autoparts store and rent a NOID light. Plug it into one of your injector connectors. Crank the engine. Does the light blink Yes/No

K I have no pulse to the injectors what could I do?

Just looked up a 91 F car and it does have VATS enabled... so earlier you said it's not a VATS issue and you have pulse? Now no pulse with Noid light...

Is your key in good shape? Does it have the resistors in it? Did you recently get new keys? Is the key switch worn/loose?

Do you have spark at spark plugs? Even if you do it could still be a faulty EST module or wiring issue at EST in distrbutor.

I'm open to other ideas as well, but these are top 2 for no pulse injectors... could also be a faulty ECM. Are there any error codes set?

[jim_in_dorris]

Okay, you injectors are fine. Your ECM is not commanding the injectors to fire. That can be a lot of different things. If the ECM is not seeing a reference pulse, I don't think it knows that you are trying to start the engine. Because you can ground your injectors and get fuel, I will assume that the fuel pump is coming at at Key On. The reference pulse comes from the distributor and goes to the ECM. Seeing the reference pulse tells the software that the engine is turning over. Do you have any SES codes set? there is one for no DRP's

[Dewayne_S]

For those following this, the problem has been found.
Friday evening I burned a new chip disabling the vats, security light went off but still wouldn't run. After a little research I found that the pinout for the 8746 was the same as a 7747 ecm so yesterday morning I drove over and swapped out the ECM's. The engine now runs. The problem was the ECM.

Crystal is now a very happy girl!