Backyardredneck

Ok I have a 90 4runner 3.0 it ran fine a day before I had to change the head gaskets I got it all back together and now it won't start I've checked all my wiring twice. Also checked and cleaned all the grounds it runs fine if I spray fuel in the throttle body.im getting power to all injectors but they are not pulsing. So I'm sure it's the ecu but I'm out of ideas and yes I've checked all the injector plugs for power and pulse.

scope103

Are you sure you're getting fuel to the rail? If the induction piping is disconnected (for instance, to spray starter fluid), the pump won't run.

Backyardredneck

Yes I have fuel at the rails if I didn't it wouldn't spray from the cold start injector

Gamefreakgc

Did you double check you have all the ground connected (ground on Passenger's side cylinder head, next to the battery on frame, top of plenum to fire wall, etc.)? Are you sure the VAFM is plugged in and undamaged? Most likely there's something you forgot to connect, seems like that's the issue more often than not.

Backyardredneck

Yes there is a ground from firewall to plenum,2 from negative batt to body and frame, the one in the injector harness that bolts to the rear of the pass head also one on driver side that goes to the block I've made sure everything is hooked up and grounded just like it was hooked up before and still no injector pulse

Backyardredneck

Also just a thought even though my runner will fire and run with fuel into the throttle body I know the igniter sends the pulse signal to the ecu is it possible for the igniter to be messed up but the rig still have spark

RJR

The injectors get a constant 12 volts (through a resistor for some versions), and are pulsed by the low side being switched to ground by the ECU. Check whether you have continuity from the low side of the injectors back to the ECU, and then check with a test light if there's any activity on the ECU side of the injectors. The "low" side should be normally high and pulse low when the injectors fire. It's less likely that the ECU is bad then that there is a bad connection somewhere.

Backyardredneck

Yea I tested all the injector plugs with a test light and both wires are hot I I looped a piece of wire to connect both wires and stuck my test light into the wire it showed power but I couldn't see a pulse with a test light should I just get a set of noid lights to double check

RJR

The pulse is pretty short, typically only about 2-10mSec, so you could easily miss it with a normal test light. You need something that'll capture short pulses.

PismoJoe

What is your fuel pressure? That should be your starting point.

Also, pulse testers work well but they will not tell you if an injector is clogged and pulsing. I have seen injectors pulse fine but do not spray.

Terrys87

iTrader: (1)

I use this https://www.yotatech.com/forums/f116...t-22re-270857/ It will show if it is pulsing. If it is pulsing, crimps, damaged wire or wiring being corroded will block off enough of the pulse to keep them from firing. Another problem it helped me find was all of my injectors were clogged. The fuel systems get nasty in these trucks depending on where you live. You may have loosened some crud up in the fuel rails and clogged the injectors.

Here is how I test an injector https://www.yotatech.com/forums/f199...l#post52188740 using a syringe with a hose as a fuel supply. On 22re motors the ground wire in the harness can get correded real bad. Sure this applies to the 3.0 as well.

Backyardredneck

Ok and the led is only going to light up if it's pulsing? Or will I have to look at it close to see the pulse

Terrys87

iTrader: (1)

It will be bright and flash several times a second. You will see it clearly. It is polarity sensitive. So if it doesnt work one way, just reverse the leads.

If you get several bright and fast flashes, your computer is good. It will be the wiring or the injector. On my experiences on two different times, it was the crimps and they just wasnt letting enough current thru. It would pass a resistance check and still not fire. It is like breathing thru a straw, you are getting some flow but not enough.

The way Toyota did the wiring in the harness is a poor design. They just crimped one wire to two others and put a piece of electric tape over it. Mostl likely you will find alot of moisture (gasoline, water, oil...) in the harness. My harness had a lot of sand in it.

If you check your injector, I use the little battery (9 volt I think it is) and just touch the battery terminal for a second a time. I had an old harness and used a connector off of it but you can get some female connectors and make a similar set up. With the syringe filled with a few ounces of carb cleaner and under pressure, it will shoot out the fluid thru the injector when you touch the terminal.

The LED has helped me with 3 problems and I know of two other people on here that it worked for as well. On a 22re, when you remove the plenum, you will have the Cold Start Injector fuel line disconnected. Not sure if the 3.0 is the same set up. If so, I would suggest disconnecting the power supply connector at the fuel pump to keep fuel from spraying everywhere.

blake.nemitz

pull the air filter lid and poke your fanger in the vafm flapper and see if the fuel pump turns on. you will hear it. never mind i just re read your post.

blake.nemitz

http://board.marlincrawler.com/index.php?topic=79085.0