2008 tacoma v6 cranks but wont start

my check engine light does not come on when i turn the key on, the truck will not start and my obd scanner cannot connect to the ecu currently. the truck has been outside parked in 25degree sun for a couple hours

 

You may have missed my previous post, but did you try any of those things? I don't know where you are located, but I assume because you are not using freedom units you are in canadia? I ask because if you are nearby I will come help you. You may have a fellow TW inmate nearby that can help too. Lots of smart dudes on here.

 

i tried unhooking sensors and nothing changed. still wouldnt start. i pushed it into the shade and about an hour later it started no problem

 

That's crazy man. If the plugs are wet (getting fuel) and the plugs are sparking it should light. I can't help you without pulling complete wild ass guesses out if you don't start trouble shooting and letting us know what you find. The only clue you gave us was that A) it won't start when hot, and B) there are no codes and can't connect to ECU during fault. Not much to go on. There are some amazing resources available here and I am certain we could get this figured out pronto if we could get some more info. My Scientific wild ass guess at this point is the immobilizer wires (behind the glove box) or maybe ECU wires/ground/connections in the passenger kick panel. If you haven't checked the battery, that could be all it is.

 

A suggestion was made to hook up a scanner. They do more than interpret CELs.

Read post #13 in this thread:

http://www.toyotanation.com/forum/7...3-96-tacoma-4cyl-hard-start-warm-weather.html

 

like i said before, i tried unhooking sensors and starting and got no where. the battery has sufficient voltage. it will start fine all evening, but during the day if it sits out in the sun it will just crank and not start. i can tell it wont start right away when i put the key in and on and the check engine light doesnt come on like it regularly would when you start your car. at this point my obd scanner wont be able to connect to the ecu either. to me it seems like there is a sensor or something preventing the ecu from turning on? ive read about the coolant temp sensor and the crank position sensor possibly preventing that but im not sure where to start.

 

Try this- http://www.customtacos.com/tech.old...06toyrm/06toypdf/06rmsrc/rm2006ta/0050060.pdf

I got there from this link,which was in the link that I posted on the last page. Everything you need to fix it is in there. Follow the flow chart!

http://www.customtacos.com/tech.old...06toyrm/06toypdf/06rmsrc/rm2006ta/0050063.pdf

 

You would start with a resistance(ohm) test of those 2 sensors. Ohm values in the FSM. There are a kazillion threads that point to a downloadable(zip file) '05-'06 FSM. Same vehicle in many respects since the 2nd Gen came into being.

 

i went through the pdf files and still nothing. im not sure where the charcoal canister pump module is tho. i got high resistance on the module wires. could it be my ecm? :S

 

I don't understand. You got high resistance in the module wires, but don't know where the pump module is? Follow the wires.

 

The canister pump module is on top of your gas tank. Try to unplug it and see if it starts. Also try to remove your gas cap to relieve pressure.
Here is the long version; your ECM takes +12V and converts it to a +5V signal that goes to the throttle body, gas pedal, canister pump module. If you short that +5V signal to ground anywhere along the way, the ECM shuts off to protect itself. The idiot light stops working indicating the ECU is dead. You further confirmed this by being unable to connect with your scan tool. I don't think the ECM is fried because it still works when cool out. My theory is that you have something clogged in your EVAP system, and when it gets warm out the fuel expands and pushes fumes into the EVAP system. When you try to start the truck the canister pump module tries to push those fumes into the intake of the motor, but since something is clogged, the motor stalls and "shorts out". If you unplug the pump and open your gas tank, it should start. That's my theory and I'm sticking to it. http://www.customtacos.com/tech.old...06toyrm/06toypdf/06rmsrc/rm2006ta/0050058.pdf

 

any chance this could be a crankshaft position sensor issue? ive heard of this sensor preventing vehicles from starting up before, could this be my issue? would it be worth while to try changing it out?

 

I recently got left stranded with my 2012. Left me with a no start condition in its entirety. At least yours still runs but yours sounds like a much more annoying issue.

There are some quick disconnect lines right next to your engine. You can disengage them by hand actually. You pinch the two plastic tangs and it releases the line. When you are having the issue, disconnect the supply side of the fuel line. Trace the lines to determine which one is return and which one is supply. Its not hard to figure out, just see which line exits the fuel pressure regulator. That one will be your return and you will want to leave that one alone. Once you determine that attempt to get a long hose you can slip over the hard side of the line then let it go into some kind of catch bottle and if alone crank the truck. If you are receiving fuel when you are having the issue then the pump is not the problem. You will have to do this immediately after you have the condition and know exactly what to do as well as have the supplies with you.

The other ones it could be due to your hard start nature after heat soak is the crank shaft position sensor, or the coolant temp sensor. The fuel pump can overheat and stop working though and that would be one of the first things to check due to my recent shitshow with that part. It was totally dead even upon testing. If you need any further help just PM and I can try to step by step walk you through or take some detailed pics.

 

On these trucks all you need at the most is 9.6 to crank and start. It won't be a pretty start but it'll get the job done. Any lower then that and it won't start and you could also cause permanent damage to your battery.

 

when my no start connection happens i have no connection to the ecu, so im not getting fuel pump or spark. at this point im trying to figure out why im losing my ecu connection when its hot. that is why im thinking the crankshaft position sensor could be the issue

 

Try to get a hold of a scanner and find out if you are receiving a STA signal (start). If you are not then thats indicative of something bigger then a bad fuel pump.


Also, it would help if you quoted the posts. Its hard to track this thread without any notifications.

 

My obd2 scan tool can't connect to the ecu. The cel doesn't come on at all when I turn the key on and the truck will just crank. I changed the crank sensor and it still won't start. It only does this when it's been sitting in the sun for awhile and gets hot. Could it be the coolant sensor?

 

Did you try this?

 

If the coolant temp sensor goes bad, it reads low to the ecu. The ecu then enriches the fuel mixture. When the engine is hot, the mixture is too rich to run. When it cools, it will start right up because it needs the rich fuel mixture anyway. So yes, it could be the coolant temp sensor, and that might not always throw up a code. It could also be a high resistance at the connector on the sensor.

 

I located the canister, but I think ill have to drop the tank to access the lines and plug. I will try tomorrow

i just find it weird that the engine light doesn't come on when I turn the key to accessory. what could be preventing that?