jamescisneros355

Hi, ive been dealing with error code 31 on my carburated 89 toyota pickup and i cant seem to find a fix for it. Ive been told that it is the vacuum switches but based on what the error code specifies im not too sure.
It says the trouble areas could be:
-open or short in volume air flow meter circuit
-volume air flow meter
-ECM
The thing is i cant seem to identify where the VAFM is on a carb 22r.
By the way the truck has a standard 4-speed tran and runs fine except for a jerk it does when the truck is running and i maintain the gas at 3500rpm

Co_94_PU

iTrader: (-1)

It's either in the aircleaner box top, or screwed into the side of the carb somewhere between the filter and the butterfly plate.

And the flow meter is a vac switch, of sorts.

jamescisneros355

The white ones are the ones i know as vacuum switches.
The one you say may be on the side of the carb is also the one i was thinking, ill try to take a pic tomorrow.

stock87

There is no VAFM on a carbureted vehicle, that's only on fuel injected trucks.

There's not a ton that can go wrong to throw a code on the carb trucks… The O2 sensor can go bad, and on some of them there's a sensor to make sure the EGR system is working (temp sensor). Are you sure you're reading the code correctly?

jamescisneros355

Thanks for the reassurance, that's what I've been thinking since the beginning but this check engine light is one i can't get rid of.

Yes i believe I'm reading it correctly 3 flashes then 1 and then it repeats over and over

abecedarian

How did you come to the conclusion the code is '31'?

If it's 3 flashes, short pause, 1 flash, long pause, then repeats, that might be 31.
If it's 3 flashes, pause, 1 flash, pause, then repeats, and the pauses are the same length that is a code "3" and a code "1".

Code "3" is an issue with the ignition: igniter circuit problem {+B, IGT, IGF}, igniter module or computer.
Code "1" is "no malfunction"....

Maybe disconnect the battery for a few minutes?

jamescisneros355

Ok that was something i hadn't considered, i just checked it seems like it might be 3 1 the pause was pretty normal. My ignition doesnt return to normal when i remove it and so i have to give it a tap or else it will make the buzzing noise when the door is open. But why would there be a code for no malfunction and why wouldn't it be before the 3

abecedarian

I don't work for Toyota so I've no idea why they did things the way they did.

And don't confuse the ignition system- coil, igniter and ECU, with your ignition switch. All your key does is turn things on and off.

So, like I mentioned, disconnect the battery or pull the fuse to the ECU for a few minutes and see what happens.

88-89 carb'd are pretty rare, at least where I'm at in California, USA. so not much is available for them.

Good luck

jamescisneros355

I reset the ecu, the check engine was off for about 4 sec and came back on, same code. I live in CA too and i see whst you mean, i was thinking it was rare because theres no info, which i find pretty cool and make me want to fix it correctly even more, thanx

jamescisneros355

quick update maybe a different or related problem;
i checked the timing on my truck first with hoses on, it was a couple degrees over 12, then i removed the hoses from the manifold to distributor and plugged them and it wasnt at 0 like most say it should be. So i adjusted it to 0 with hoses plugged reved it up and at about 2000 or 2500 it would "hiccup" (vrrrrrr-vrrrrrrrr-vrrrrrrrr). I connected the hoses back on checked the timing and it was at about 3 degrees, tried reving it again and it would seem to loose power at times, any suggestions?

oh and i checked for vacuum leaks, found a couple small ones because the hoses end stretched out and now i only hear the air being sucked into the carb (it kind of sounds like a vacuum leak)

derf88

hi I just joined I noticed your problem wanted to know if you ever Came to a solution ?I have the exact same truck year with the same code same problem

jamescisneros355

Negative, I found that a good amount of the hiccups came from the gas pump being old. I had the 3 white vacuum sensor changed but no difference. I still want to change the other sensor with 2 hoses (I think VSV) because the bottom tube slipped out.

derf88

K thanks , all my vsv are working I tested them ...did your truck stumble while driving in 2nd gear sometimes and in 3rd gear ....with lack of power but if you feathered the gas then it would accelerate normal ? Cause my 89 does that too.

jamescisneros355

Yup exactly that, although it kind of does it on every gear for me (4Speed MT) if i keep my gas pedal steady, then if i accelerate its normal. Let me know if you find a cure plz.

buickid

Wow, an 89, with a carb and 4 speed. The carb isn't entirely surprising, but the 4 speed is! I thought they were pretty much all 5 speed by then...

derf88

Found my problem. ... code 31 was the vacuum switch valve # 1 and 2 were switched(worng location)... #1 in #2 spot on the fender but vacuum lines in correct location. So all I did is switched the switches in the correct location on the fender and connected vacuum lines according to diagram in cleared codes no more check engine light. Truck runs great.