Why is my 2015 not flex fuel

[swathdiver]

...and who's going to look for a yellow replacement cap?

I did. As for running it, I never thought I would either but a hurricane helped change my mind. Because the fuel costs so much less, I actually saved at least one and one half cents ($.015) per gallon compared with high test. Will I run it all the time? I dunno, have to see who has it around where I live, I fueled up while out of town.

L83

You're good to go for E85

 

[AZRiverRunner]

I believe that any of the direct injection 5.3L, which is 2015 + Tahoe are NOT Flex Fuel E85 certified. It's not in my manual or on my fuel door/cap. Warranty would be void according to the manual if used and had a problem.

 

[swathdiver]

There's no mention of E85 or Flex Fuel on pages 1-27 and 9-69 through 9-71 in your manual? Well, err on the side of caution and don't run it then.

GM even has L83 dyno numbers with E85, 376hp and 416 ft lbs torque.

 

[swathdiver]

This subject has bothered me so I did a little more googling and came across this:

GM TSB : PIP5227 (edited for brevity)
Please note: There was a change during the production of 2015 Full-Size SUVs, and with the beginning production of 2015 Full-Size Light-Duty Pickups, shifting from a standard E85 capability on all of these vehicles equipped with the L83, 5.3L V8, to an optional E85 capability, requiring selection of E85 capability through vehicles equipped with RPO code FHS.

Note: Vehicles equipped with RPO FHO, E10 gasoline are certified for this fuel type and cannot be modified to allow use of E85 flex-fuel.

In the past, GM would give a new name to an engine, like the LH6 becoming the LC9 because of the Flex Fuel but I guess they were tired of adding engine numbers.

So, you fellas with L83s and black gas caps or filling ports, you probably have RPO L83 and FHO.

 

[LI Tahoe]

This subject has bothered me so I did a little more googling and came across this:

GM TSB : PIP5227 (edited for brevity)
Please note: There was a change during the production of 2015 Full-Size SUVs, and with the beginning production of 2015 Full-Size Light-Duty Pickups, shifting from a standard E85 capability on all of these vehicles equipped with the L83, 5.3L V8, to an optional E85 capability, requiring selection of E85 capability through vehicles equipped with RPO code FHS.

Note: Vehicles equipped with RPO FHO, E10 gasoline are certified for this fuel type and cannot be modified to allow use of E85 flex-fuel.

In the past, GM would give a new name to an engine, like the LH6 becoming the LC9 because of the Flex Fuel but I guess they were tired of adding engine numbers.

So, you fellas with L83s and black gas caps or filling ports, you probably have RPO L83 and FHO.

Jame- I appreciate that this subject has bothered you, since I am the OP, it really bothers me. I looked up the TSB you posted and it clearly states.

Addition Note: For SUV models, FHS is only available for fleet and government ordered vehicles; for LD Pickup, FHS is available for all orders. The default fuel capability is E10 gasoline, specified for vehicles equipped with RPO FHO. E85 flex-fuel capability is specified for vehicles equipped with RPO FHS Vehicles equipped with RPO FHO, E10 gasoline, will be equipped with a black fuel cap and will not be equipped with a flex-fuel sensor. Vehicles equipped with RPO FHS, E85 flex-fuel, will be equipped with a yellow fuel cap and will include a flex-fuel sensor. Note: Vehicles equipped with RPO FHO, E10 gasoline are certified for this fuel type and cannot be modified to allow use of E85 flex-fuel. Warranty Information


since 99.9% of us do not have a fleet and or government vehicle-- still not go on E85

 

[HiHoeSilver]

Good find @swathdiver. Wth would they make this change so confusing and in the middle of a model year? Not to mention publishing a bunch of conflicting data. Jeez...

 

[swathdiver]

It looks like GM went back to the way the engines detected E85 with the Gen III, a separate sensor. That would explain why the engine designator wasn't changed. It also probably means that there is no difference between an L83 able to run E85 and one able to run E10 only. It's the sensor and computer programming that determines such. That's the way the details that Matt posted seem to be.

Well I hope nobody ran E85 with a black cap because of my previous posts. Hopefully they'll read through the posts.

 

[GTNator]

My 2017 rental Yukon SLT is flex fuel and it's clearly marked in two places.




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[jeffbco]

What's your engine RPO code?

 

[Undeserving]

My 17 5.3 has no indication anywhere that it is flex fuel capable. I looked for decals on the windows, filler door, etc. Nada.