Flex fuel or gas?

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Dutchman

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According to my VIN, my truck is flex fuel (Z). But I had to drop the tank to replace a line this weekend and the lines and pump match what online stores have for gas only trucks. Can the flex Tahoes be converted to gas only? I rarely even see E85 fuel anywhere, much less use it, so gas only is perfectly fine. I'm just wondering if mine has been converted some how.

Here's the top of the fuel pump. I looked it up and it's labelled gas only.
fuel-pump-top.jpg
 
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Dutchman

Dutchman

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So, no responses so far. Is there an easy way to tell if my engine is gasoline only? My VIN says it’s flex, but I think it may have been swapped.
 

OR VietVet

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Dutchman

Dutchman

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The VIN is 1GNEK13ZX3J283139. As you can see, the eight digit is Z. When I bought it, the engine looked very clean and runs like a champ. I think it has been replaced with. Gas only engine. Is there a way to tell?
 

OR VietVet

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@915_Tahoe, would the vehicle come down the assembly line with all attachments and electrical for both options and so would all be there depending on which way the VIN 8th digit is?
 

swathdiver

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Consider that the previous owner put the wrong pump for whatever reason, maybe GM put the wrong pump in by accident on the assembly line or a dealership. Should be date codes on that stuff.

The big difference between the two systems is that the Flex pump can flow more fuel and has plumbing for the flex fuel sensor and larger fuel injectors.
 

OR VietVet

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If you look at the two choices for pumps, there is a world of difference. At least it looks like a lot of difference to me anyway.

Gas/Robust system fuel engine code T: https://www.rockauto.com/en/moreinfo.php?pk=496248&cc=1412244&jsn=1067

Flex engine code Z: https://www.rockauto.com/en/moreinfo.php?pk=7056044&cc=1412244&jsn=1068

Gas except robust system: https://www.rockauto.com/en/moreinfo.php?
pk=1300750&cc=1412244&jsn=1065


Looks to me like the first link is a match but maybe the 3rd link as well. Whatever a "Robust System" is?
 
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Dutchman

Dutchman

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Consider that the previous owner put the wrong pump for whatever reason, maybe GM put the wrong pump in by accident on the assembly line or a dealership. Should be date codes on that stuff.

The big difference between the two systems is that the Flex pump can flow more fuel and has plumbing for the flex fuel sensor and larger fuel injectors.
So, if that pump has worked previously, I should be okay with the same as a replacement, right?

That leaves me with my original question. Is there a way to tell, by looking at the engine, if it’s flex or gas? Because I think it has been changed. It’s in too good of shape to be original, I’m thinking.
 

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