Miss12052

my fiance recently bought a 94 yota 4runner...he was driving home the other day and it just stopped running on him while going down the road. He's ASE certified but this truck is frustrating him because he can't seem to figure out what is wrong with it. Did an OBD2 test on it pulled up code 24 (intake air temp signal fault), 31 (air flow meter circuit or vaccum fault) & 52 (knock sensor fault). He has replaced the MAF sensor and it's still not running. It's turning over it just will not run...any advice is greatly welcome at this point...

wyoming9

iTrader: (1)

Did the check engine light come on when it quit or did he pull up old codes that were never cleared??

there is it just quit

as just slowly had a loss of power

then it quit just like you turned off the key.

How about the simple things did he run out of gas??

Is he the type that drives around with the gas gauge between 1/4 and empty ?? Even knowing better!!

Did the timing belt break? the woodruff key shear off on the crank pulley.

Pretty much comes down to a fuel problem electrical or mechanical

If you can`t plug a tool into the engine to tell you what is wrong it can be repaired.

Back to the basics Good luck:jessica:

OverTheEdge

Has he been able to confirm good spark, fuel and compression? Also, ran into a proplem of my own that sounds similiar. Malfuntion in theft deterant system Disabled the ignition system (spark) also affected the starting system threw the starter interupter cicuit. Good luck!

Miss12052

in answer to both replies: it was running & then lost all engine power like instantly, check engine light never came on & still isn't on...dunno if it was old codes that weren't cleared, we just bought it about a week ago, gas tank was full, he hates driving below half a tank...timing belt looks like it was recently replaced (no visible wear &/or tear) has good spark, fuel & compression..pulled out the viper anti-theft system and still nothing...

OverTheEdge

This is interesting, an engine needs four things to run
1. Spark
2. Fuel
3. Compression
4. Air
If you have these then the engine will run, with all due respect this is fact.
Now on the other hand if all are present but one or more are weak(spark) or low(fuel/air flow) then it could prevent it from running. I would verify good numbers on all. also would check all grounds for clean tight connections. Please keep us updated on diagnosis and repair.

OverTheEdge

The above post was based on the assumption that the injectors are indeed allowing fuel into the combustion chamber.
I do not recommend this to anybody reading because of the potential of grave harm. But You say that your fiance is ASE CERT as am I. Therefore, in a situation like this I myself would give the engine a quick burst of starting fluid threw the thottle body, re install the air intake, to act as a spark arrest and see if the motor will fire. If so this would tell me that there is a fuel delivery problem. If it does not fire. it would lead me to the ignition system(Spark)
[B]DO NOT TRY TO USE GASOLINE FOR THIS TEST![/B] Had a fellow co worker set himself and the customers car on fire a few years back. It was not a good situation.

vital22re

iTrader: (2)

ASE and its running yet? 94 did not have obd2. Obd2 came out in 96, 95.5 for the tacoma's. Has he checked any of the fuses ? The code 52 will not prevent it from starting but rather how it runs. The other codes for the AFM will though. Did he replace the AFM with a used unit? or was it new? The AFM sends a signal to the COR(circuit opening relay) that energizes and sends power to the fuel pump.

Does he have spark?
If he sprays some starter fluid in it does it run for a second or two?

James Woods

iTrader: (1)

ASE just means that you can pass a test, doesn't mean you can fix anything. I have seen some darn good techs fail some ASE tests and some guys that can't do an oil change right pass the test. Last time I took the test I had just left the bar and didn't care if I passed or not, took it in 15 minutes and passed. Nothing against your Fiance as I don't know what kind of a tech he is, but why are you here asking questions and not him?

Getting that out of the way, has he checked the FSM or have access to Alldata? Has he checked any of the above yet?

OverTheEdge

Direct and to the point JW.

OverTheEdge

http://www.ncttora.com/fsm/1990-1995_4Rnr/Toyota.4Runner.1990.1995/contents.htm[/URL]

Prairie Dog

Howdie, I am new to Yota tech site. Just read about your dilema. If after you have checked out all the good advice from all the replys to your S.O.S. and if nothing seems to resolve your problem. I had an experience years ago with a
new buick and while driving on the highway on a business trip my perfectly running vehicle suddenly
just up and quit and would not start. After an expensive tow to the nearest G.M. dealership and
3 days in the shop Voila! Mystery solved. The distributor shaft gear was completely stripped balder than a chicken in a tornado.You might want to pull the distributor and check the gears. And like
i said it may be a long shot but it is easy enough to check out. Hope your problem is solved soon,good luck.I know 4-Runners can be mysterious. I own a 92 Runner Medalist Limited nice rig just mischevious thats all.

OverTheEdge

Very Good advise that i overlooked. To expand on Prairie Dogs input, simply remove cap rotate engine and see if rotor turns. Nice P.D. See Ya!

Miss12052

figured it out...when previous owners replaced timing belt they didn't bother resetting the timing so he reset the timing & replaced the old belt with a new one...running like a champ now & thanks for all the input...i was asking simply because i'm more pc literate w/ forums & what not...plus he was literally banging his head against the wall in frustration as to what the problem could have been...

OverTheEdge

Back on the road again, excellent!

vital22re

iTrader: (2)

That doesn't sound right. You mean the timing belt jumped a couple teeth?

That does happen as timing belts get worn out in time.

AZSPEED

Same thing happened to mine but i'm still banging my head against the wall.

fourthdb

This just happened to me last week! I was scouting out camping sites for my wife and I to take a camping trip and when I started on my way out of the woods my 2002 4runner just shut off. I still had all lights coming on if I turned the key. They engine would turn but would not start. I know 3 different mechanics and had all three go over the vehicle to try to figure out what was wrong short of taking the engine apart. We cleaned sensors, replaced spark plugs, replaced fuel filter. Everything we found online for fixes would not fix it. So the 3rd mechanic decided to look at the timing belt and sure enough it had jumped. My 4runner is now at a shop to get the timing belt fixed.