Hey Scotty! Darian here. I just purchased a used 2014 Tundra SR5 with the 5.7 Flex Fuel. The truck has 112k miles, is 1 owner and has been taken care of extremely well. Anyways I’ve had the truck for about 40 days now and after just a few days of owning it, it’s began to have these long/hard starts where it would crank for almost 15 seconds before finally starting up, then it would idle poorly for a few seconds before seeming to be fine. (Once it warmed up it didn’t do this anymore, only when cold and even when cold sometimes it wouldn’t hard start so bad) granted at this point I put 500 miles on the car or so and the only fuel I’ve put in it is 87 octane NO E85. So I take the truck to Toyota and long story short I paid them 142.00 dollars to reset the fuel system they told me it was reading there was ethanol in the system and was flooding the engine when cold. I said fine and it was perfect for about 3 weeks then it slowly began to hard start again then it was back to the cranking for 10-15 seconds before finally starting... so i take back up to Toyota (at this point I’ve put roughly 1700 miles on the truck and still only 87 octane NO E85 ever since my ownership. They tested the fuel and said there was 84% ethanol in the fuel (the previous day I filled it up with 87oct) so what they did again was reset the fuel system for free this time and sent me on my way and said if it does it again we’ll have to dig deeper. Great it was I’m thinking so here’s my theory. Toyota advertises the tank as being 26.4 gallons, and even when the truck is basically on E is only takes just under 21 gallons. I’m not sure if this truck has a separate fuel reserve tank/area holding 5 or so gallons of E85 (maybe previous owner used E85 is what I’m thinking) and maybe when it gets lower and just at anytime is slowly bleeding this fuel reserve back into the tank so it doesn’t go bad and replenishing that with fresh fuel? At this point I’m lost and Toyota doesn’t seem to want to help me with this. If you could give me your input that would be greatly appreciated. I’ve done some research on the Tundra forums and people have had this problem before but everyone had the fuel system reset once and never had an issue again? Weird to me, looking forward for your input! Thanks

it does not have a separate holding tank, just one gas tank as far as I've ever seen. And gas and ethanol mix as soon as you fill the tank up, that fast. But, try a couple tanks of shell V power gas, cause that is supposed to contain no ethanol. Most other gasolines have at least10 percent ethanol in them at the pump

Yeah my solution after leaving the dealer the second time was to use premium fuel and see what happens. It’s weird because it is the flex fuel model so it should be ok to have E85 in the system