Cranks, starts, dies.

I have a 2003 Tundra V8 4.7L that cranks, starts for a second, then dies.
Sometimes I'll turn the key and, VROOM, starts right up and it drives beautifully, no problems at all.

I have replaced the fuel pump relay, the fuel pump, the fuel filter, the MAF sensor, replace cracked hoses, checked wiring and connections. I purchased a membership with, "Just Answer," and spoke with several different, "Experts," none of which had a clue as to what the cause is. The experts all wanted to know things I don't have the equipment to measure. When it does start it runs like a champ, rendering checking measurements moot.

There were a few times I towed the truck home after hours trying to start it. The next morning, VROOM.

Now, when it does start, I'll go to a jobsite and let it run all day to be sure I could drive, not tow it home.

I am positive that I am not the only one who has/is experiencing this issue.

 

It's not a normal occurrence around here if that's what you're meaning.
Many times right after someone has changed their timing belt they'll find themselves in same situation. Their crankshaft position sensor wiring harness was reinstalled wrong and gets nicked by the serpentine belt.
Have you checked the fuel pressure ?

 

The strange thing about all of this is: When it does start it runs fine. I

 

believe that because it runs fine, when it does start, means the fuel pressure and any other measurements
are fine. Otherwise the truck would not run.

 

Common issues to sort through:

Power and ground wire connections and condition. Prone to corrosion.

water intrusion into interior electronics. Fuse panels and computer modules are subject to corrosion due to windshield and cowl leaks.

I’m assuming there are no codes? I’m assuming that the critical parts are all OEM, not aftermarket garbage? I’m assuming the maintenance is up to date, timing belt, MAF and TB cleaning etc? No misfires?

 

You are correct on all of your assumptions. This issue has been going on for better part of a year. I have triple checked everything with the exception of the ECM. Is there a way of reprogramming the ECM? Would that even help?

 

It really sounds like something is shorting to ground. Crankshaft position sensor wire would be where I'd start. If it's nicked and shorted, guess what? No fuel, no start. And it could be jiggling around causing what seems to be random no starts.

 

Remove the negative battery cable for 10 minutes. This will force re-learn. Does it continue for the next few startups?

Also curious. Do you park outdoors? If so, do you notice this happens after, say, a rain/water event? Interior leaks are common. @KNABORES covered above. Into the fusebox and into the ECU being the two which would be detrimental. Into ECU would be hard to diagnose, and tends to be hit or miss on the symptoms, and can come/go. Fusebox is sometimes easier, it'll usually munge up 2-3 or more circuits, so you'll have a few different symptoms of electrical gremlins.

What's the state of the throttle body, currently? Can we see a picture of the opening, with the full throttle plate? Have you popped out the air filter and looked for signs of rodent activity? A piece of filter breaking free and getting stuck in the MAF could cause this. As could a failing MAF. FYI, the OEM MAF is made by Hitachi for the V8. I recommend to stick with it if you measure its resistance and find it's out of spec.

I'd proceed by going to store and getting a can of MAF cleaner, and a can of throttle body cleaner, specifically. Disconnect the negative battery cable. Clean the MAF (need instructions?), let it come back to room temp and install, don't start the truck while it's still ice cold from the cleaner, weird shit can happen. Clean the throttle body by spraying the TB cleaner into a cloth and wiping until you get no shit stains. Clean the front and back sides of the round throttle plate but DO NOT (or try to avoid) letting the throttle plate slam shut and NEVER spray TB cleaner directly into the TB. Reassemble, reinstall the negative battery cable, and go back to driving.

 

Wiggled the wires feeding a fuel injector and, VROOM. Hopefully it will continue to start.