xdescrubx

I have read numerous threads pertaining to non starting vehicles. So far I have not found a solution. I have a 1996 4runner sr5, 130k, v6, auto, 2wd. The vehicle has been very reliable and just stopped starting all of a sudden. I was driving on the highway, got off and parked at the store. Ran perfect. Came out and would not start. I have good spark and fuel. I also can smell unburned fuel coming out of the exhaust. I know fuel is getting to the cylinders. I tried to check the ecu, via obdii connector under the dash, with my scan tool (which has been verified working on another vehicle). I get a communication error. I have never had a check engine light come on since I bought the truck. I took the ecu out and it looks like brand new on the inside. The only other thing that is different, is the IAC is making a loud buzzing/ticking noise with key on, engine off. It never did that before. From what I read its supposed to make some noise. Can the IAC cause a no start problem? I thought a vehicle can run even if the IAC messed up. So I am leaning toward the ecu being toast. Any suggestions? Thanks in advance.

edit: I also confirmed that all fuses and relays are functional.

wyoming9

iTrader: (1)

Just what do your plugs look like??

About the only thing that will take out the ECM is getting water inside or a massive voltage spike

Some contact cleaner should cure your failure to connect

The MIL light does light when you turn the ignition switch on?? So you know the bulb is working ??

xdescrubx

The MIL does come on when key is on/engine off. I cleaned the obdii connector with electrical contact spray. I cleaned the IAC and throttle body. Spark plugs look good. There is unburnt fuel smell in the cylinder. Still cannot connect to the ECU. I get power at the plug but no link via scantool. I put everything back together and It still doesnt want to start. I sounds like it may want to start for a millisecond. It seems the engine is getting flooded enough to where its loosing compression due fuel washing oil out of the rings. Can a faulty ECU cause a rich condition?

wyoming9

iTrader: (1)

Anything is possible

One thing I forgot is physical damage to the wiring harness

Rodents chewing wires is quite possible

something shorted and burned

poor ground connection

Then since you have not caused a code to trip

injectors stuck open can fill cylinders with fuel

xdescrubx

Thanks for the reply. I thought about the injectors, but what's the chances of multiple injectors stuck open? I wouldn't even suspect the ECU, if I could communicate with it on my scantool. I think i'm going to order one off ebay...30 day money back guarantee. See what happens. Ill post results.

xdescrubx

So, it turned out to be the ECU. Plugged in a used one, and it fired right up. The scantool also communicates with the ECU now.