'97 Tacoma starting/running problem

'97 3.4 Tacoma 4X4.....
Truck started stalling while driving, wait an hour and would start again. Drove around for a month with it occasionally stalling and then wait to start. Changed fuel pump, filter and same results. Finally it would not start and sat for about a month.
My son just got in the truck and started it after a month of sitting, it ran like a champ for about a month. Now resumed not starting.
Since then it has started 2X, ran for less than a minute and then died.
Cannot get a code as the engine won't start.
MAF has been cleaned also.
Any suggestions?

 

Maybe a bad TPS sensor, or distributor?

 

The engine does not need to be running for codes to be read. When it does not start, does the CEL (check engine light) illuminate when you turn the key to the run position?

 

Thanks for the replies.
The CLE light comes on when key is in run position.
The current no start situation after a very heavy rain storm; (not sure if that has anything to due with the issue) but seems to have happened previously.

 

Today was able to plug in OBD2. Check engine light is on, OBD2 says cannot connect to ECU.
My son's friend tried a dedicated scanner and he could not connect either.

 

What kind of OBDII scanning tool are you using? Is it one of those plugs that connects wirelessly to your phone that you read via an app or a specific OBDII scanning device?

 

hi, my mechanical knowledge is limited but I am interested since I have a '97 3.4 as well, how many miles are on it?
I have only had a similar issue once and found it to be that a mouse had crawled up inside the air filter housing box and had been nibbling on the element which messed up some sensor
have you eliminated the mouse in filter housing problem?

 

Yes mine is, a BAFX: it links up on my wife's Toyota with no problem.
I do not know the brand scanner my son's friend used. When it wouldn't link up to my son's truck, he tested it on his with no issue.

 

We cleaned the MAF and also new fuel pressure regulator and igniter.

 

I have a 1997 3.4. I’ve been having the same issue. New ecu coming in this week. I’ve checked all sensors, used multi meter on all wires, checked grounds and all fuses. Scan tool reads linking error no communication. Put the scan tool on another vehicle, it works fine. Will let you know if ecu was the issue.

 

Thanks hope it works out .

 

Mine was the ecu too. Runs like a champ. Thanks.

 

Was able to put in some time on my son's truck today trying to see why my scanner cannot connect.
When we got to the truck it started and ran rough for about 2 minutes; scanner could not link to ECU.
Truck would not restarton a number of tries, but fired up for a few seconds and then died.
CEL stayed on until I pulled the EFI relay then came back on as soon as I plugged relay back in. I changed the relay and it did the same with the replacement.
Tried disconnecting every sensor to see if I could get the scanner to read the codes but still a no go. Only one we couldn't get to was the crank pos sensor.

Would the ECU be bad if the truck started occasionally?
My son started the truck a few times this past week with it running for a bit then dying.
This event all started after a very heavy rain followed with about 2-3 weeks of rain.

 

I found this... maybe it is your ECU.

 

Thanks for all replies.

 

crank position sensor or ECU is my keyboard guess...

 

Is it getting fuel? Is there spark? I had an issue with my 5v reference circuit and couldn’t get my scanner to connect. It ended up being the MAF plug, the ends at the connector were exposed. I put a new connector on and it solved the problem. From what I read if the Ecu isn’t getting the reference voltage from certain sensors it won’t turn on the fuel pump. I have a 99 3.4

 

Thanks for all the replies, after all it was the ECU.
Put in a rebuilt ECU and truck started right up.
CEL off, sounds and runs great.

 

odd... the Toyota ECU's are usually rock solid dependable.