Long crank

I have a question for anyone who might know the fuel system better than I for our 5.7 gas engines. My son has a '15 SR5 and has lately had some problems with a long crank (like 10-15 seconds). It has not thrown any codes. He took it in to an Autozone to check for any stored codes, and the person that he spoke to there told him that the fuel pump check valve might be to blame, requiring the long crank to get the fuel rail up to pressure. I don't necessarily disagree with that, but the suggested temporary "fix" was to turn on the key and not start, then after 10 seconds or so to turn the key off, then crank as usual. I'm not sure about it, but I told my son that I don't think our trucks' fuel pumps will run unless the ECM senses a turning crank. Once started, the truck runs fine.

Any comments and/or suggestions on helping him out is appreciated.

 

https://www.tundras.com/threads/res...ectional-scan-tool.123799/page-8#post-3842351.
sounds like this might be your problem.
my 2016 had a long crank then would finally start and run rich for a few seconds, after that would run just fine. only happened when it was cold out, below 40 degrees

 

Thanks, but it's not flex fuel.

 

The potential diagnosis provided is correct for one possible cause of long crank. There are others. He was incorrect about waiting 10 seconds. That works on some vehicles, but not tundras. They do not turn on the fuel pump until the starter engages.

 

Yeah, as it turns out, my son does have a flex-fuel truck. has the P1604 fault. He'll need to get the density reset and also might eventully endup needing the pump and all that. So we're working toward that angle now. Appreciate the comments.

He's got an independent Toyota shop that he's working with now.

 

If it long cranks after 2+ hours of not being on but doesn’t long crank if you turn it off then back on within a few minutes then it is likely the fuel pump check valve, which keeps pressure in the fuel line. This will not throw a code, fix is a replacement fuel pump usually as it’s the same unit.

Otherwise could be other things like bad fuel pump, alternator, ecu, poor fuel, clogged intake, dirty maf or throttle body etc.

 

I had this start about a month or so ago. My truck is '17 with currently, 255,000 miles on her. I took it to toyota and was told I needed a fuel pump, but they're backordered, so I took it to another shop, installed an aftermarket fuel pump. I also changed the spark plugs and replaced the battery as it was bad. The hard start persisted intermittently.. This morning, I took it back to toyota and had them reprogram the ECU and reset the Alcohol density, it was reading 79%, now reads 8.63%. The truck is definitely starting normally and seems to be running better and my fuel mileage after changing the fuel pump went from 12-13mpg to 16-17mpg. Last week, I drove from Houston to Tulsa and went 500 miles before I fueled and I still showed 60 or so miles to empty. For what that's worth..