saitori

Hi everyone, can't get my 87 4runner running

Up until now:

The head gasket blew due to electrolysis. I rebuilt the engine, replaced the head and had the injectors cleaned & checked. I put in a new rotor, cap, wires & plugs. Also put in a new O2 sensor.

I put the engine back in and turned it over. I had a rough idle apparently due to cylinders 1 & 4 not firing (it was running off 2 & 3).

I checked the compression - It's good in all 4.
I checked for spark - It's good to all 4.
I checked cam timing, distributor alignment and distributor to plug wiring - All correct.

The only thing left (I think) is fuel. I started looking into the fuel by trying to switch the 1 & 2 and then the 3 & 4 injector connectors to see if that change which cylinders fired. The wires were too short to try this Still had the top of the intake on). After I tried this, the engine no longer turned over. It wont run on even 2 cylinders like it used to.

After, I checked the wire harness from the injector connectors back to where the ground wires from the ecu splice from 2 wires into the 4 separate injector grounds. There is no observable corrosion.

I now have the top of the intake and the throttle body removed so I can get to the wires and injectors.

The engine wont start but I try to crank it over with the noid-lights attached to the injector connectors and they do NOT start flashing. If I ground the injector wires from the splice location to the lower part of the intake the light turn on (and stay on). Also, I get 12V when I check the positive side of the injector connectors. So, I get power to the injectors and the ground is good at least to the splice point in the harness. I think the injectors themselves should be good because they were cleaned and checked professionally.

I'm left very stumped...

1 - (Original Problem 1) What could be the cause of cylinders 1 & 4 not firing? It seems fuel related but I don't know what...

2 - (Newer Problem #2) What has caused the engine to stop running all together? Is it a continuation of problem 1? Is it a new problem that started during the diagnosis of problem 1?

One more thing. When the engine could still run, I could hear the opening circuit relay (by the fuse box) and the fuel pump activate when I pressed the vane in the air flow. Now when I try this I do not hear the relay or the fuel pump activate. Could I have blown the relay? How do you test the opening circuit relay? I think this MIGHT be the reason for Problem #2. Still no idea what's the cause of Problem #1.

Feeling a bit desperate at this point. Thanks in advance for the help. It's much needed.

Terrys87

iTrader: (1)

My injector splices would pass a resistance check and still not fire the injector. I would suggest removing the splice and solder them together.

Here are some of the other things I checked when having problems>>> https://www.yotatech.com/forums/f199...l#post51897320

92yoterDD

Is this a 22re or 22r? Believe it or not a bad MAF sensor will keep the fuel pump from coming on.

jarheadtex

I was thinking simple...EFI fuse. However, if you have power at the injectors that cant be it.

vital22re

iTrader: (2)

ecu could be going bad. It sends a pulsed ground signal to fire the injectors and goes from 2 ground wires then split to 4. Make sure you have all your grounds for the ecu bolted and clean. Then start testing the wiring starting from the ecu

RAD4Runner

+1.
After I left shop after engine rebuild, my truck sputtered. I took it back and shop quickly found bad splice on that harness. That harness gets exposed to extreme conditions so its very likely that connections there get brittle or corroded. I wish I had the opportunity to wrap that harness silicone insulating tape.

scope103

If the fuel pump doesn't run, the truck can't possibly run. The easiest way to check the VAF/COR circuit is with the fuel pump test jumper. I don't know when the connector changed, but this page shows both locations: http://www.4crawler.com/4x4/CheapTri...CheckConnector

You said that you checked cam timing; how about ignition timing? I almost hate to ask because it's so basic and fundamental, but you didn't mention it. While you're at it, you can also use the inductive pickup on each plug wire to check for spark.