Flex fuel or gas?

[Wylie_Tahoe]

Have you confirmed a VIN match on at least 2 other locations on the truck? Like dash and door match and dash and frame match, etc?

 

[Dutchman]

I had not thought of that. I’ll check that ASAP.

 

[iamdub]

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.

The engines themselves are all the same and I'm pretty sure the only difference between FF and non-FF are the injectors. I don't think the manifold nor the fuel rails are any different since using FF injectors on a non-FF engine for performance purposes (nitrous, boost, big cam, etc.) is a common swap. The injectors do look different. Their electrical connectors are different as well.

FF injector:



Gasoline-only injector:

 

[Dutchman]

Thanks @iamdub. That’s the kind of info I was looking for. I’ll check that when I look at the VIN numbers.

 

[mattbta]

What year? Does it have an inline fuel filter, underneath the driver door area? At some point in the vintage, only the Flex Fuel motors got serviceable fuel filters.

 

[Wylie_Tahoe]

Based on the VIN the OP posted, its an 03. My 03 F/F has an inline fuel filter canister

 

[Fless]

The OE fuel filter will most likely still be there even if the engine was replaced with a non-Flex engine. Doesn't really tell the story. The fuel injectors will.

 

[OR VietVet]

If it does have a filter, it needs changed for sure.

 

[Dutchman]

There is a filter on the frame rail. And I will be changing that as well.

 

[OR VietVet]

Some here will not agree but I always install a new fuel pump relay when I do an electric pump replacement. It all stems from a story from when I was running shops years ago.