02 tundra mystery

I have owned my tundra for 16 years never had any problems. 6 months ago it just started randomly dieing I have replaced countless parts nothing seems to help. It won't leave you stranded but it just dies I have narrowed it down to the fuel. I hooked a pressure gage into the system and it runs 44 lbs I put the gage on my wiper so I could watch it while driving. It runs great and then you can see the gage start to drop it goes to 0 and idles rough and then dies as soon as it dies without cycling the key the pressure jumps back to 44 and it starts right back up. To save time. Here is a list of new parts. Throttle body, injectors, MAF, fuel pump, fuel filter, inside fuse block,ignition, alternator, crank sensor, cam sensor, 3 relays several vacuum lines I used a after market fuel pump oriellys it was in for about 5 months before this problem started. Took It to Toyota ended up with new throttle body no difference. I'm going to hook up volt meter on the fuel pump wires next so I can see if I'm losing power to the pump when it dies while driving.

 

Sounds like you need a denso fuel pump. Were all those parts you replaced bought at O'Reillys?

These trucks are finicky. They like denso or OEM brand parts.

Also, it sounds like the fuel pump relay/resistor is going bad...

 

Just gotta say this because I always say this: It's never the fuel filter

Replace the fuel resistor next, sounds like it's about the only thing you didn't. It's the finned thing mounted on top of the driver wheel well, under the brake booster/MC.

I don't love aftermarket parts, but if it behaved EXACTLY the same with the old shitty non-OEM pump and new pump, I'm thinking that's not the problem.

We can give you full diagrams of the fuel pump circuitry if you want. The symptoms don't smack of fuel pressure regulator to me, so I'm not going there.

This video is not 100% accurate, but have you run through all the steps they show, and through all the diags they show for debugging?

https://www.youtube.com/watch?v=VoerlgT8pck

 

Oh, and reason I say it's resistor - which you can test with an DMM, testing its resistance - and buy OEM replacement - let me know if you want the instructions to test it, if you have a DMM.

The fact it does it while you're just driving, that resistor in conjunction with the relay kicks the pump into low/high mode. I suspect when it's kicking to low mode, it's actually dumping power to the pump. I'd blame the relay first, but you said you replace it, so ...

 

Yes, I agree, fuel resistor is the culprit, it matches the symptoms. The fuel system is 'weird' on these trucks in that it primes for two seconds when you turn on the key, then turns back on when the ECU detects the engine is cranking, and then at some point, changes the voltage to the fuel pump from high, to low. I think your fuel resistor circuit is shot and when the change over happens, your pump is getting turned off instead of turned to low.

 

Can you bypass the resistor just to see if it is the problem?

 

According to this post you can: https://www.tundras.com/threads/fuel-pump-resistor.54240/

 

Oh and @Baldobbie2263 here's the procedure to test the resistor: https://www.tundras.com/threads/2006-double-cab-fuel-pump-no-power.36822/#post-2962132