Dies while driving

Hi everyone, been lurking for a while but finally got stuck.
My 01 with 3.4 has had a random misfire on 135and 6 usually light load condition. The truck one time wouldn't start after we stopped at a store about a month ago. After a minute or two it did and it was all fine. Recently it will stall and not restart for a while, and today I finally had to tow it home. I was initially happy because I thought I had something to work with. But it fired right up when I rolled it in the shop.

The truck has new plugs (denso) and wires, new coil packs, compression is good, I swapped relays while waiting on the tow truck. Fuel pressure was good when I checked it after it started.
I'm baffled by the intermittent no start condition. It does crank just won't fire. I don't know if there is spark or fuel because I can't replicate it when I have tools around.
Thanks for your time and ideas

 

It starts and runs fine cold but shuts off hot?

 

Yes, but it could run for a whole day or 20 minutes, I can't find a pattern

 

When I had a similar problem it was the fuel pump relay. I hope it’s something simple. Good luck. Edit: EFI relay

 

I actually got to swap a known working relay with the efi relay while it wouldn't start yesterday and it didn't change anything. I saw some posts mentioning the relay below the fuse panels in the cab as well so I swapped that one as well with no change.

 

Start simple and go from there.......
......grounds and battery are #1 and easiest.....

new fuses.......then those tiny relays.....efi...whatever...

next is the bigger relays......fuel pump.......
pull fuel return hose off fuel pressure regulator and put on a dummy long one and crank and check for copious amounts of fuel coming out......

Inject

Next I'd move on to bigger electical stuff......like the main lines bolted to engine fuss box.....make sure all around box is good....all bolts and connections tight.....

Then maybe starter switch......they fail when hot....start fine when cold.....at first.......then get worse.........starts dying leaving a stop light....


Next is go find all the engine sensors that are not oem factory....
its temping to pay $20 for toyotic part instead of the real $200 one.....
you'd think people would be smarter than that....
Look at all the engine harness....where it touches engine or any brackets......


Final word....I didnt trust a 25yr body ground to my engine to run injectors/plugs....
so I beefed up and ran a braid cable from neg post straight to my intake plenum...........you dont want those guys thirty....do you....

Also if running old vacuum hoses or pcv one hasnt been replaced recently....maybe now would be a good time....

 

what's your location? have you been running fuel system cleaner and/or HEET in your tank since the issues started?
sounds like it's getting worse, which leads me to believe it's fuel filter related. water in the fuel can get worse this time of year if you're in a cold weather climate.
otherwise, I'd say it's likely an intermittent short in the wiring.
it could also be the pump itself if most of your issues come when the tank gets low, but it runs fine when full.

 

I'm located in hawaii so the cold isn't really a factor. I have run several tanks with fuel system cleaner and I just changed the fuel filter the other day after i towed it home. I also pulled the fuel line and pressure tested and it is good. The other day when it quit it had just over half of a tank. I'm currently just driving it with a can of starter fluid and a scan tool hoping it will quit so I can see if I'm missing fuel or spark. I'm wondering about the crank sensor. Since there are 2 cam sensors if one was bad you would expect a code. But a bad crank sensor shouldn't kill the truck..

 

I will never forget this one truck that had the weirdest issues and ended up being an intermittent failing crank sensor. It wasnt bad enough to set a code but it was doing all kinds of weird things. A new crank sensor fixed it.

Might be something worth checking.

 

Could be a bad spot on the pcm circuit board. Like a solder joint that opens up when hot

 

Alternator? Seems similar to and exp3rience I had with an 08 tundra... minus that misfire you described. I wish you luck