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Flex Fuel Sensor MS3

8K views 22 replies 8 participants last post by  01yellerCobra 
#1 ·
I picked up the PNP Megasquirt system for my 3.4 build. I had a couple of questions about the flex fuel sensor. I was planning on running the GM/Continental sensor. Is there a pigtail offered by GM? Also where has everyone been plumbing the sensor in a return style setup. I have a Fore system. Trying to get the last few things figured out.
 
#2 ·
I got my sensor from Summit and it came with a pigtail.
Here's a pic of the sensor with the adapter I made that splices into the return line.

Gas Wood Machine Auto part Metal


ks
 
#3 ·
Good to know the summit piece comes with a pigtail. I didn't see it in their pic. I will call my fab guy and see if he can make something similar. I can't TIG to save my life.
 
#6 ·
I plumbed the sensor in the return line. Seeing as I run a deadhead system I figured that would be more beneficial. However I have yet to get the sensor to work. I used the ECU 12v for power and I'm guessing it's not providing enough power. I keep getting an error code. But to fix it requires pulling the tire and fender liner.
 
#8 ·
The PRO-M piece looked pretty great so i went with that. Really trying to take advantage of this MS3. Flex fuel and adjustable traction control should be fun.
 
#9 · (Edited)
When you guys start to implement the flex fuel sensor(s) be sure to check out the plumbing diameter, most use a 5/16" tube. A 5/16" OD tube with 1/32" wall thickness is only a 0.250" ID for fuel flow. there are a few ⅜" OD tube sensors also available. A ⅜" OD with 1/32" wall tubing provides a slightly larger 5/16" id for fuel flow.

In the real world either would likely work adequately for ethanol content sensing purposes, The issue comes when you begin to plumb the sensor into the circuit. If you choose to do it on the feed side and you have a #10 AN feed line the sensor will need to be plumbed in parallel to the #10 feed line. No big deal right? Be careful if you use a "Y" adapter. You want all branches of the adapter to accept #10 AN fittings. On the sensor leg of the "Y" adapter use adapters to mate with the required #6 or #8 AN to EFI plumbing adapters to plumb in the sensor. On the other leg of the "Y" fitting use a #10 line to maintain the flow capacity you need to feed the engine.

Depending on which sensor you use (5/16" or ⅜" tube) you will need an appropriate AN adapter. Russel offers the adapters through Summit and Jegs. Here is a pic from Summit of the Russel listing for both adapters;

Automotive lighting Font Cylinder Gas Liquid


Note the ⅜" diameter fuel line adapter at the bottom of the listing uses a -8 instead of a -6 AN fitting.

Although it may not matter, the fuel flow through the -8 plumbing will be greater than the corresponding flow through the #6 plumbing which means the sensor will report more quickly any changes in the incoming fuel's ethanol content with the larger plumbing. If you search for sensors by tubing size on Summit you can quickly sort the alternatives into the two sizes and choose the one you prefer to use.

Ed

p.s. If you choose to do the plumbing on the return side be aware that reduced tubing diameters can produce a back pressure to the returning fuel creating an unintended and unwanted rich condition whenever return fuel flow exceeds plumbing flow capacity. Additionally placing the sensor on the return side only tells you the horse has left the barn after he is gone. For best engine fueling you want to know about the fuel's ethanol content before it is injected into the engine - which will argue for a feed line placement of the sensor not a return line placement.
 
#13 · (Edited)
They are very impressive guys, Tony. That gizmo is just the tip of the iceberg for what they offer. Their design uses an internal bypass to avoid choking off the fuel supply to the engine. I ordered one as soon as they told me about the internal bypass! Thanks for the heads up.

Here is a gizmo pic;

Trigger Air gun Gun barrel Gun accessory Composite material


Ed
 
#14 · (Edited)
Of course as soon as I see this, they are sold out of them.
Ed, do you know if it’s compatible with the ProM sensor Josh used that reads temp as well?
Edit: Never mind the question regarding the ProM sensor. Went back and read through some pages and realized this isn’t necessarily needed if using the the ProM sensor and vice versa!

Thanks
Ken
 
#15 · (Edited)
When I ordered mine Ken, I asked for the one that would work with a sensor that has the ⅜" fuel nipples. There is also one that can apparently accommodate the 5/16" fuel nipples. The 5/16" hardware would probably work fine but just to be safe I chose the ⅜" plumbing instead. One of the sensors that uses the ⅜" plumbing is the Chevrolet AC Delco part# 13577429.

I have seen OEM AC Delco manufactured versions of the sensor with that part number at price points ranging anywhere from low $60's to high $80 numbers depending on where you source them. I would be cautious of any potential low buck knock off product offerings because of the potential engine damage possible if the sensor is unreliable. This is an item I feel safer about, knowing it is a an original AC Delco OEM component.


Ed
 
#17 · (Edited)
Ken, and everyone else who reads this thread;

The AC Delco sensors have a built in temp sensor which is the third wire in the harness, so you have a fuel temperature monitoring capability should you decide to use it.

Although I have previously said this, it doesn't hurt to repeat it, The knock off versions of this sensor can be a problematic choice for a supercharged engine. Errors in the fuel content / makeup and potentially temperature, if you monitor that, can result in significant piston, cylinder, head gasket and valve damage in a supercharged engine. The few additional bucks for the genuine article is cheap money well spent.


Ed
 
#18 ·
Thank you Ed, as always I greatly appreciate your detailed guidance and input in this forum and past PMs!
Do you by chance recall the vendor you purchased your AC Delco flex fuel sensor from?

Also to anyone else reading, the piece linked by Badcobra https://www.motionraceworks.com/pro...-sensor-mount-for-feed-or-return-6an-8an-10an and discussed by Ed is back in stock at Motion Race Works. I just ordered mine.

Thanks
Ken
 
#21 ·
Glad I hopped on here before my turkey comma kicked in. Ordered one of the sensor mounts for my winter fuel system refresh. Just gotta pull the trigger on the pump now.
 
#23 ·
The Continental brand sensors are also really good. Or so that's what my research showed me. I ended up ordering one since I couldn't find an AC Delco sensor with the shorter connections. I only had E85 in my tank for a bit, but comparing the readings to a spread sheet I found showed both really close.

YMMV
 
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