ColbyJack

So I picked up this 4runner a few months ago, my first toyota, for $800. I feel like I got away with robbery, I love this thing. It had sat for 5 years under a tree and didn't start, I had to trailer it and ended up changing the gas tank/fuel pump/alternator right off the bat and she was running great until recently.

Stopped for fuel one day and went to restart. The truck would crank as normal but would not continue to run unless I kept my foot on the gas pedal it would die. Other symptoms: the truck will shimmy and vibrate as if being turned on and off very quickly while Im going down the road and the check engine light will come on.

I pulled the check engine code as "oxygen sensor" So here are my concerns.

Will replacing the O2 sensor be the last of my worries? I know the 1990 has only one before the cat converter.

Also what other maintenance/tune up do you recommend for a vehicle that sat for that long.

Thanks for any advice.

fork

firstly what engine are we dealing with here

in what shape is the fuel filter in

ColbyJack

V6 3. Slow

Replaced fuel filter when I changed the fuel pump

fork

have you done any other maintenance to it? here's a link to the fsm to rule out the oxygen sensor http://www.ncttora.com/fsm/1993/engine/101heatedox.pdf (btw the entire FSM is available there if you haven't found it yet)

thook

Which O2 code did you get?

Servicing the injectors would be a very wise thing to do. It's quite possible they're atleast part of your problem. Of course, you could try some Seafoam or cleaner of choice, but sitting that long it may not do the trick completely. Pintle injectors do not like old fuel or sitting for long periods.

Hell, for that matter, it might be a good idea to get a professional fuel system flush and do the injectors.

ColbyJack

I followed these instructions and got code 5

http://www.troublecodes.net/Toyota/

alltracman78

Start with the O2.
There's no way of telling if there are other problems til you fix that and see how it runs.

93toyrunner2

Cap, Rotor, Plugs, Wires, Air filter, Oil change after running SeaFoam in the crankcase for 100 miles. Run a half can of SeaFoam through your intake system before you replace the O2 sensor. SeaFoam in the gas tank, 1oz per gallon of gas, to clean out the injectors while driving.

ColbyJack

Ok I picked up the O2 sensor and replaced it, and I'm still having the same problem! Still getting the same check engine code also.

What could cause the O2 code to keep going off after its been replaced?

Im going to replace the plugs, cap, rotor, wires but after that Im clueless.

93toyrunner2

Wiring short. Grab your FSM, and start testing (check continuity) the wiring from the ECM to the O2 sensor. It runs down the drivers side frame from under the drivers seat area, and can get damaged. Check the wires all the way to the ECM for continuity.

Jbowls

Did you check the fuel pump fuse? Mine sat 5 years also and blew the efi fuse first time I filled the tank. I'm sure you fixed it by now this is old

coloradotom

Is this a thing, does the EFI fuse blow very often?

Just now while home at lunch I was putting my EFI fuse back in, took it out this morning to reset the CEL. I really looked at it because it appeared that it could be inserted two different ways (180 degree rotation).

In another thread I described how I got a new O2 sensor, drove the truck about 120 highway miles, then had the CEL come on next time I got the engine up to operating temp. I took apart the connection to the sensor from the wiring harness and found some sloppy splices. Could have been shorting? Which could blow the fuse?

Will the truck run without that fuse? Does it truly control the EFI, because if so I would think the truck would fail to even start without a good fuse.

So?

james92toy

I'm thinking you need to check your timing also maybe a small vacuum leak or egr valve is stuck open a little .

Gamefreakgc

It will work either way, it's just a fusable link. Doesn't matter which way, it will hold the current.

Those sloppy splicing could most definitely cause a fuse the blow. Probably the main cause besides water damage for most blown fuses is bad wiring. The EFI fuse doesn't necessarily power the whole system, the injectors and such will still run if I'm remembering the wiring diagram right. I believe the fuse is just to the ECU, so without it you'll get poor fuel management and other issues.

masterchiefhasayota

Yes, the engine cannot run without that fuse. Are you having a problem with it right now? If you are, I believe I could help alot. Mine just recently kept blowing. Worked on it for weeks, finally fixed it. Turned out that the wiring going over my fuel rail was melted. several wires were severed, and it was grounding out.

Jbowls

When my efi fuse blew my 4runner would not start at all, just my experience. It did this only once so far but I keep a glovebox full of fuses just in case now.

masterchiefhasayota

Well if your o2 sensor is bad, that can lead to efi fuse blows. Same with a bad fuel pump, a bad circuit opening relay, ground issue in efi system, or a bad ecu, the mother computer.
Mine was a ground prob, as I said. Yeah, Keep extra fuses, just in case.

Jbowls

I'm almost positive mine was from this old 250k fuel pump. I haven't check fuel pressure to see yet but may be worth looking into for you if the problem continues after you fix the wires.

masterchiefhasayota

Well that would make sense then. You're probably A-OK.