2004 3.4L 5VZ-FE Sudden Death

Hi all, I am completely stumped and not sure what to check next.

tl;dr
===============
My truck is suddenly dying (while driving) and then will not start until some time (at least 10 min) has passed. Cold starts are fine.
When it is warm it turns over and _almost_ starts but just dies. This happens intermittenly, not every time. But is becoming more frequent.

About My truck:
===============
* 2004 Tacoma 3.4L 4Wd (5VZ-FE)
* 150K miles
* Sparks changed about 40K miles ago (Iridium I think)
* New fuel pump and fuel filter
* Timing belt changed at around 100K miles
* Scanned and there are no error codes.


The long version:
===============

This first started about 2 months ago when I drove it sort of hard because of an emergency (higher RPMs/more aggressively).
Later that night I drove somewhere else (it would achieved operating temp) then it wouldn't start after having been stopped for a bit.
It would turn over but not catch on (at first I thought is was battery but it wouldnt jump either).
The mechanic I towed it to surmised it needed a fuel pump, so it got a new pump (Bosch), filter, and screen.
He messed up and didn't attach one of the lines from the pump (the one that goes to the canister I think) and a check engine light
came on. He corrected that (grumble) and had no problems.

Three weeks later my wife left the car idling (probably before it had gotten to operating temp) and it suddenly just died.
It restarted right after that though. Later that morning, it repeated this but this time would not restart until it had sat for about 10 minutes.
Note that in these cases the car was _not_ getting a chance to get warmed up.

I took it to a different mechanic and he cleaned the MAF and throttle body (didnt take it off, just cleaned the throat) and changed the fuel filter
for good measure. The MAF was quite dirty. The truck started up better and we had no problems for the next two weeks. We even drove
it on the highway and some light off-roading.

The other night, I had another emergency (dad was in an accident) so naturally I was a bit more aggressive driving to get him. That night we left the truck
idling for a while and once again, it just died. Ever since then, the truck will get up to operating temperature and then will either die
while driving (even if I keep the RPMs up by downshifting or keeping it higher RPM at a stoplight in neutral). It simply doesn't want to idle when it is warm.
Now it is even dying while I am pressing the gas pedal.

I scanned it and there are NO scan codes reported. (My last mechanic flashed the codes so we could easily see new ones). After reading a ton of forums,
my thinking is that the TPS is failing, so I took it off and mechanically it is ok (springy), but I am not sure the best way to electronically test it safely as a n00b.
Note that this truck has the 4-pin TPS which are hard to find (thanks, Toyota).

My friend says it must be fuel system related because that wouldn't report error codes, but I don't understand why the truck cooling down would 'fix' the problem then.
My understanding is that when the truck warms up a loop is created in the computer's interaction with the sensors and somehow perhaps the sensor is reporting
wrongly so the fuel gets cut off and she dies.

I uploaded a video [here](http://youtu.be/KlkAqc8dP5Q) that demonstrates the car having been warmed up, then dying (at about 18s in) when I move the throttle. After the car has died there is a
mechanical buzzing/ringing sound coming from the throttle body area and a irregular 'ticking' sound that sounds like something is trying to engage. It is almost
like the throttle sensor doesnt know that the car has died and it still trying to do something. I can't guarantee that is where the ticking sound is coming from though.

Thanks for reading my post! Any advice would help me narrow whether this is electrical, fuel, etc.

 

In the repair manual (factory or haynes type) there will be OHM values. Open, shut and sweeping. Those you will need to check.

Just for fun go check the coolant temp sensors resistance. Being that it seems to temp related i would start with all things that measure temp.

 

My forum lurking found this awhile back. http://www.customtacos.com/tech.old/files/tsb/hard_cranking_tsb.pdf

 

Look at the grounds, mainly the one that goes the the fuel injection harness.
If your lucky that will be the culprit. If its a dead short you will have to have it on a diagnostic computer to tell you exactly whats going on when it starts to die so you know where to start looking.

 

Interesting my 03 5vz used to die out of nowhere right after putting it into reverse going down my driveway which was on an incline. Right as I shift into drive it would stop.
It had to be something electrical, it would throw the battery and oil cel. Never found the issue but now when I back up I put it in neutral with the emergency brake on and then shift to drive, no issues since then.

 

might be vacuum lock, plugged vent or charcoal canister is sucking a vacuum until gas no longer flows. truck shuts off and after a few minutes the tank sucks in enough air to break the vacuum to allow fuel to flow again until boom, its sucked into a vacuum again.

run it with the gas cap off and see what happens or if you cant do that then take the cap off as soon as the truck dies, it is supposed to have a "little" suction so you should hear a little air being sucked in but not a lot, if its hard to remove or a loud sucking sound then something is plugged up, either the vent system or the charcoal canister is bad

 

Thanks all I am out trying these things (except the wiring harness replacement ) today and will report back.
@keakar the mechanic who put in my fuel pump told me his mess up was that he didn't attach the line to the charcoal canister. Could the week or so driving around without that line hookup cause this kind of plugging? Is that the same canister you are talking about?

 

Today I took @keakar's advice and drove around without the gas cap on and it is still dying. It _seemed_ to go longer without dying but I suspect that is a false positive. It wouldn't start any quicker either.
My multimeter is dead so I couldn't check my resistance on the TPS wiring or the other suggestions so tomorrow I guess that is what I'll be buying.

What I don't get is why cleaning the MAF and throttle body throat a while back had the truck running better for a couple of weeks. It seems like if it was electrical it would be consistently tripping. Gremlins!

 

the gas cap eliminates it as being an issue but it doesn't rule out the charcoal canister. since it lasted longer with the cap off I think you are on the right track so now you need to figure out how to bypass the charcoal canister and see if that is your problem. it was the canister for another member a while back who had very similar issues going on and he had replaced the fuel pump and everything before he figured it out.

I have no clue how to properly bypass one so is there anyone you know that you can swap canisters with for a test drive?

 

Ill check around @keakar, thanks. I found a couple of threads on bypassing the canister. I expected driving around without a gas cap would throw a check engine light but it didn't. Not sure if that is significant tho.
I'm considering dropping my fuel tank and having a look at what this mechanic did to see if there are any other issues in the lines he dealt with.
My buddy said the fuel system is the only thing that doesn't throw codes so mebbe this is the right track.

 

Easier to pick the bed up off the truck. Drive it around without the bed so that you can mess with the canister and fuel stuff without crawling under and getting fuel in the face. The charcoal canister is under the bed too so everything you need to troubleshoot will be more easily accessible if you take the bed off. It is a lot easier than you think. Just get 3 buddies to help when you need to take it off and put it back on. I've done this a couple times with mine while trying to find gremlins from my frame swap (had access to a forklift though).

 

I thought I'd update status on this. I took the truck to a different mechanic who _did_ find fluctuations in the fuel pump using a pressure gauge and voltmeter so I returned it to the original mechanic to replace. He begrudgingly replaced it. So far the truck has performed ok with the new pump and I am not sure whether he screwed it up by failing to attach the line going to the canister or whether the pump was just defective. Either way, I won't be returning to that shop. I'll report back here if the pump fails again.
Thanks all for offering input. Great community here!