I have tested all the relays. Fuel pump comes on and is pressurizing the lines.
The injector harness to the injector is getting a constant 12volts. But when I turn engine over the voltage never drops or stops. I know the injector has 12 volts all time and the computer grounds them as they fire. The engine will fire up on starting fluid. But quickly dies.
This 4runner has sat up for YEARS. I cleaned the tank and installed new pump
There is something I know that is simple that I am over looking. I know its a sensor that is unplugged or something like that.
Found answer to problem. There is a double ground wire that bolts to that steel hose octopus looking thing down about mid ways of the head and under the intake throttle body. pulled the Throttle body off so I could get at the injectors and test them better and thats when i found the ground wire. Makes perfect since that the ground was missing from the circuit. As that was what the ECM uses to trigger the injectors to fire. Without it all you get is a few seconds of run and shut off. I thought it may have been a clogged injector at first, but when i used the NOID light to test the signal, there was no pulse, only steady voltage. I am now pretty good at trouble shooting they system now, I know where every relay and what triggers what and why. Not that I say its a good system, its a crazy system. But it is a solid system that when its parts are in working order and wired right :ha_ha: works..

 

You should check injector pulse with a noid light, not a test light or voltmeter.

 

I did use a noid light.

 

Are u positive ur getting gas to the injectors? Double check ur coil wire and connections. Sounds like u have a clue what ur doing, with my luck it's always the easy stuff that bites me. Also, if ur using starting fluid the engine won't stay running if u have the intake boot unhooked. U will have to spray the starting fluid then quickly hook the boot back up before starting the truck, or spray it before the afm. But I'm not positive if that will hurt the afm or not. I just know it won't start and stay running with the boot unhooked.

 

Yeah I spray the starting fluid in the intake tube at the throttle body then put back on. The engine runs so I know the coil is working.
Something is not telling the injectors to work

 

at the minimum, the cold start valve should be dumping fuel into the intake, which should at least fire the truck momentarily.

since that's not working, it could be defective, or you aren't getting any fuel.

right after the system sounds like the fuel pump is running, shut it off, and crack the fuel line at the cold start valve, see if any fuel leaks or sprays out.

 

It's getting fuel. It's the dang injectors that are not pulsating like they should.

 

sounds like it's not even firing the cold start valve... is the harness plugged into it?

you should be able to hear the injectors clicking with a mechanics stethoscope, or possibly even with a wooden dowel or something between your ear and the injector, when the key is in the "start" position, at the minimum.

so we would be saying that you see the noid light pulsing(never tried that myself), which means that the injector is getting the signal to fire, but you can't hear the injectors clicking?

 

The injectors have 12 volts on them. They are Not getting the signal from ECM to ground out or fire. So they are not firing. Verified with my hand on them and with light

 

you can narrow it down by checking for a signal at the other end of the harness, at the cpu box, under the passenger side kick panel.

at this point it would probably be a good idea to follow the troubleshooting steps in the factory service manual, it has a complete flow chart, based on the symptoms.

please keep us updated.

 

fwiw, the injector wiring in schematic shows two connections coming off of the cpu, but they are tied together inside of the harness, it looks like Toyota altered the wiring after fact.

that area where they hacked the harness is prone to corrosion and breakage, but it's typically an intermittent failure... you can't tell it's bad with a meter, because there are typically still a few strands of wire connected.

what's disturbing here is that you didn't feel a pulse at the cold start injector either, and it's on a whole 'nother circuit(?).

 

I checked the harness. It looks good. I got the FSM I gonna start there and work though the trouble shooting list.

 

Any one know what signal the ECM needs to trigger the injectors?

 

Well figured out how to bypass the neutral safety switch wiring

 

still have the issue of the injectors not firing.

 

There is a harness ground that bolts to the intake, can only see it with the throttle body off. It was not connected and once connected back. It fired up and purrs like kitten now.

 

wow! a simple fix...

thx for the follow up.