Flex fuel sensor - LS swap

Tomeal

G-Body Guru
Apr 17, 2016
783
93
Clyde,pa
Anyone running a flex fuel sensor in their LS swap? Was curious what all was involved with using one.
 

64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
4,998
113
Upstate NY
What ECM? I thought you were using a stock ECM IIRC?
 

Tomeal

G-Body Guru
Thread starter
Apr 17, 2016
783
93
Clyde,pa
I am going to use the stock ecm. The motor and ecm are flex fuel capable. I believe it to be one wire from the ecm and a 12v and ground to the sensor. One day this week I was going to search for the sensor on my donor vehicle just to see what was involved. I know there will be settings in the tune.

Was mostly curious if anyone else here has done it.
 

81cutlass

Comic Book Super Hero
Feb 16, 2009
4,322
113
Western MN
Yes I have. It's in the return line. Works great
 
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Tomeal

G-Body Guru
Thread starter
Apr 17, 2016
783
93
Clyde,pa
Is there any difference with where you place it at in the line? Closer to the tank or engine? Or just in a convenient spot.

I think I will plumb it in on mine when I get to fuel lines.
 

64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
4,998
113
Upstate NY
Location is not an issue for normal use. But if you have it in the return and you run out of fuel or can aeriate the return fuel for any reason, then it will make E read as gas which will mess with your tune alot.

For 90% of all swaps, though it doesn't really matter.
 
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Tomeal

G-Body Guru
Thread starter
Apr 17, 2016
783
93
Clyde,pa
Thanks guys! When I get around to pulling the sensor off the donor I'll update here again for anyone else that may look into it down the road.
 
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Tomeal

G-Body Guru
Thread starter
Apr 17, 2016
783
93
Clyde,pa
Crawled around under my donor vehicle tonight looking for the sensor, can't find the d@mn thing. Going to stop at the local dealership and let them pull a schematic and tell me where it's at.
 

Tomeal

G-Body Guru
Thread starter
Apr 17, 2016
783
93
Clyde,pa
GenIII or GenIV? GenIII I think you have to start with the correct Suburban tune, not as simple as just enabling it in the tune. Sounds like you may already be there though.
Im trying to find the physical sensor on the donor vehicle. I'm not to the point yet of the tune. Although that will come next. Figured I'd at least plumb it in when I do fuel lines. If I don't hook it up/ enable it now, at least I don't have to cut it in later.

BTW...2012 GMC 3500 box truck, flex fuel from factory. Hoping it just a case of retaining the correct hardware and properly setting the tune for it to work.
 

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