Hard start?

I made an account to ask questions here. So here we go. I have a 2012 Toyota Tundra with the 5.7 flex. Just recently it began to be hard to start. It blows white smoke on start up and knocks for about 3 seconds then runs alright. My gas mileage has gone down to around 6 mpg. I’ve done a few things to diagnose this. My first thought was was of the worst. My truck has 154000 miles and I drove it hard (towing, WOT, and jumping it when I was a teenager). So it developed slap in the timing chain. I read timing in real time and it’s throwing 34 degrees in at wide open throttle. So naturally I thought it may have slipped a tooth. But I found a few other things as well I’m this process. The alcohol percentage in the fuel is reading 77.3% which I know is not normal. I’ve ran 87 octane since I bought the truck with an occasional tank of 91 or 85 when I don’t have the cash. Worst case could be timing, best case could be a bad tank of gas. What do y’all think? Any other tips for diagnostics, have y’all heard of this problem before?

codes reading: P0300, P1604
Fuel pressure is good as well as injectors firing correctly and consistently.

 

This exact thing happened to my truck! Maybe someone can chime in but there is Toyota service bulletin out about this issue. Toyotas fix is to replace fuel pump, flash ECU and reteach the alcohol sensing. I asked my dealer if they could do just the flash and relearn and they agreed but made me sign something saying I understand this may be temporary fix.

 

I think this is the tsb
T-SB-0166-19

 

Thanks Dupey, I’ll look into it and update

 

Check my post on how to DIY if interested

 

can you post a link? I’d like to see it!

 

White smoke on startup is usually indicative of coolant seeping into the cylinder. The fact that it stops after a few seconds indicates that the coolant has exited the cylinder(s). Maybe do a compression test? Look for evidence of coolant in the oil?

 

https://www.tundras.com/threads/aftermarket-fuel-pump-install-w-pics-flex.91148/#post-2581853

 

Mine would do that, but only during cold weather. Took it to the dealer and they hooked it up to the tech stream and checked the alcohol density. My ECU though I was running 86% alcohol. They wanted $8-900 to replace the fuel pump, filter and alcohol density sensor. Long story short, the new pump assembly fixed the problem. Took it back before my 1yr parts warranty ran out and the density was fine.