90 4 runner needs doctor
 

:dunno: I have a 90 4 runner that idles around 500 rpm, sputters and jerks while driving as if gas cut off. I've replaced fuel filter, wires, plugs, dist cap, rotor, timing belt, vacumm hoses, EGR, PCV, Max Air flow, adjusted Idle, oxygen sensor, checked cat converter, and numerous other system parts. this has myself and a good mechanic stumped. I would hate to have to junk it, put a lot into it and am holding off on further restoration until I can fix this. Anyone have any wisdom on this? It is not constant, but right now for 5 days. Any help appreciated.

What engine? I assume 3slow because you said timing belt?

Its a 3.0L V6, Manual transmission, 5 Speed, 4X4.

sounds like a vac leak of some sort

I've checked and replaced Vac hoses, can't find any leaks. I have recently mixed synthectic oil with regular and was told this could gum up. Is this a possible cause? I'm new to the forum and have been reading some of the threads, it seems i've attempted the majority of fixes with the same luck as everyone else. Has anyone dropped the gas tank yet to look at pump screen? that is one i'm looking to do but dreading.

Mine did that and I found the wire to the fuel pump got a crack from a mod to the center consol might be worth looking at since they run under there

TPS:
http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

Otherwise, here's the Factory Service Manual for a '93 truck, yours should be identical:
http://personal.utulsa.edu/~nathan-buchanan/93fsm/

Thanks, I'll check that out, I also found yesterday while changing oil that one of my new plugs wires was corrosive. I'll dig into that today. Used a gunk additive in oil before changing, did help alittle.

X2 on TPS. Then, I'd check the coolant temp sensor (not the sending unit for the gauge).

And, sythentics are designed to be compatible with petro oils.....have been for quite some time. So, they won't sludge when mixed.

yeah try taking the hach off the botom (under the rear seat i think you have one too) then find the power wire for the fuel pump and cut into it and place a 12+ jumper to it and see if that fixes it it might then you know you have to replace that wire and check timing it could be off just a lil and be causing this to and the TPS bench check her!!! take off the TB and check the tps with a ohm meter that way you know its ok hope its helps

Yeah, running on 5 cylinders could explain your problem ...

NOTE: for plugs, wires, and O2 sensors, NGK or Denso ONLY. Do not use Bosch!

Unfortunately, Allen, 2nd gen's don't have that convenient little "hatch" feature. But, I tell you what......if I had the tools, I'd make one for my '92!

Thanks for all replies, I will continue to check all. Installed new wires and plugs again, found some problems with the recent ones. in process of checking fuel pump and lines ( one has minor crimp near filter) TSP checked out alright. with everything i've done it is trying to run better. Let you know when I find the elusive key. Thanks.

If you are down to the point where it is "trying to run better", pick up a can of Seafoam. Put half of it in the gas tank, administer the other half into the intake through a vacuum line. Search, there's a huge thread on how to do it and the benefits you can expect to see.

I did that last week, Lots of smoke for about 15 minutes. I'm dropping gas tank tonight to check all workings. time allowing should have her back up in a week or two.
Thanks.

So, I dropped the tank, turns out there was a pinhole leak from the feeder tube on sender and the main line dropped off when touched. never saw the leaks but they where there. Once I get the parts that toyota milked me for, I'm hpoing it solves the problems. Thanks for everyones suggestions.

For any interested. After fixing fuel lines and replacing the Pump and sender, still had the stutter on acceleration. Changed EFI relay, Helped a little, Changed main relay above ECU and truck is running almost perfect. MPG is back up tp 18 MPG. Also for those with the Starting problems, I have gone through 3 starters, 2 batteries and a alternator. Also changed battery cables.
After putting in a gel battery the truck still wouldn't crank. Decided to check voltage everywhere in the starting system. Found only 5 volts at inciter wire. Traced lack of voltage to hack job previous owner did to wires connected to ignition. 23 splices in all. Cleaned up that mess. Truck starts every time now.
Hope this experience helps some others.

Mine does the same thing as yours, idles low, doesn't run well for a while, and stutters and stops. It died just now (might have had something to do with the fact that there's no radiator fan in it since that thing exploded and took out the radiator last week...I put in a new radiator already though)

I spent $1300 at a mechanic's to get it running right. They changed the timing chain, changed out a vacuum solenoid, and a fuel leak among other things. It's been running pretty well since then until today.

I'm really started to get pissed off at this hunk of s***. I can't wait to sell it.

Meanwhile, how hard is it to mess with the TPS? I have an DMM...Can I test it without taking it off?

the link that tc gave above tells you what to do.
here it is again:
http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

you said the main relay is above the ecu, that would be behind the pass side kick panel right? where is the efi relay, in the box under the hood? i have an 88 runner 22re
where did you get these, the dealership? about how much did they run ya if you dont mind me asking, you can PM me if you would rather do that.
thanks for any help you send my way!
dewitt