nuknuk

95 4runner 3.0 v6, After months of messing with this thing and just swamping parts, and testing, I am 100% sure the fuel injectors are not firing.

I have changed the ECU with one off of Ebay
spark plugs are dry
I have 12v to both wires on injector with key on
new injectors and pigtails
timing is good and have signal on all wires
have pulled plugs looking for fire, all good
new distributer, rotor, and plug wires
I have fuel supply and pressure, fuel pump is good to go
ground wires 3 that I know off, one back of engine, one by the power steering pump, and the one on the fender by the battery all seem good.
cleaned Air sensor and tested it, it good, thought it was bad, but its not.
no fuel leaks or vacuum leaks, I look every time I mess with it.
new battery

nuknuk

I going to peel back the black plastic cover and tape on the wire harness from the ECU to the injectors and look for breaks.

nuknuk

wires look good

wyoming9

iTrader: (1)

What about the ECU ground on the cam bearing cap if it has not been moved .

These can be quite finicky at times .

Has that been cleaned real well ??

The ECU you bought was tested that everything works ?

scope103

Any codes? 14 will shut off the injectors (but it should reset so that you can re-start, but it's something to look at).

nuknuk

I haven't been to the cam bearing so I haven't touched any of that, all this did start after I changed the knock sensor. It was running just find before I changed the knock sensor, now I haven't gotten it to start up since. The ECU I bought used off of ebay, didn't test it, but it acts the same as the old one does.

nuknuk

I have checked and no codes were coming up, but its been a while so I will check again and see if anything new popped up.

RustBucket

iTrader: (1)

Check your main ground wire to the negative terminal of the battery. I had a poor connection there once from using a crappy O'Reilly's clamp cable and the resistance was too high to let the injectors fire. Put an ohmmeter between the negative post and the frame -- should give you basically the minimum reading (maybe 0.1 ohm or something).

nuknuk

I have codes 31 and 24, and I replaced the battery ground wire with a new one, and still no start. I guessing its 24 or just 4, cant remember if it flashes twice at the beginning of the codes or not every time it starts over.

nuknuk

I did unplug the VAF meter to see if it would start up but plugged it back in while still trying to start it. Not sure if that is why I have codes now. I about to set the thing on fire, will never own another 3.0 again.

nuknuk

ok, so I just cleared the codes, and then tried starting it again, then checked codes again, and have no codes. The VAF meter does make a tapping noise, the vane is jumping, only when I press in the gas pedal while trying to start it. Anyone know why this would happen?

Trents3.slow

Don't get frustrated. I'm sure it's something simple and its being over looked. Did you check if the EFI Relays are functioning? I KNOW THIS IS A NO NO!! but what happens if you spray a little fuel into the intake (after the maf). Does it fire?

anndel

Did you check the EFI relays as mentioned and the EFI fuse as well?

Trents3.slow

Double check your connection at the MAF. If that isn't right the fuel pump won't kick on.

Charchee

You may have already done this but try jumping the two terminals on the little diagnostic connector by the fuse box that will allow the fuel pump to run all the time while you test it and will take the MAF out of the equation temporarily. Like stated above, the fuel pump will not run if the MAF isn't working correctly unless you have it jumped. Let me know if you aren't familiar with this trick and I'll elaborate.

Somebody help me out here. Doesn't the ECM need some feedback from the coil / igniter before it will send the ground signal to the injectors and allow them to open? I am aware of this part of the circuit but have never had to troubleshoot it. Do a search on it if nobody comes back on this. I'll find the pages from the FSM and walk you through it if you need me to.

One more thought. Safety First Here. You could remove your cold start injector from the plenum and have someone crank the engine over while you safely direct the fuel into a container, if any will come out. If nothing comes out, you either have no rail pressure or you are on the right track with troubleshooting the signal to the injectors. Either way, that should rock you off dead center and give you something new to consider.

Take your time and don't let it get you frustrated. These engines are really pretty easy to troubleshoot. You just have to get to know them. I'm looking for a challenge and mine's running fine. I'd be glad to help if I can.

Trents3.slow

Solid advise. I can't back you on the signal to the ecm talk because I have no clue. I'm positive there is simple wrong with his truck. We will figure it out.

nuknuk

I know of one EFI relay and fuse which is under the hood, they are both good.

nuknuk

Ok thanks for the reply, I do know how the jump the box for the fuel pump to come on, I have done it before with no results but will try again. I am sure my fuel pump is kicking on while cranking it, as I have tested that by cracking lines. I haven't checked the cold start injector so I will. But thinking its fine being I got fuel pressure to the fuel rail. I think your right about the ingiter/coil sending a signal back to ECM for a ground. I don't know how to test that. I know it is sending spark signal due to testing it with my timing light.

nuknuk

I have the connector on good with the wire clip securing it.

Charchee

You are always going to have rail pressure so long as your fuel pump is working and the test is not to see if the cold start injector is in good shape. It is to see if you are actually getting signal through your injector harness to the injectors. You see, it's the only injector that you can actually hold in your hand while it's doing it's thing. If it works or doesn't work, you are going to really narrow down your list of possible problems.