[jimib]

After I had a mechanic install a Holley Sniper EFI setup, the fuel gauge reads ¾ full even though there’s only about 3 gallons in the tank (gauge worked fine before). Regrettably, he lost his business.

So I removed a few screws and pulled the dash forward enough so I can get behind the fuel gauge. The fuel gauge is well grounded, the pink wire to the “I” terminal on the gauge reads 12.5 volts, and when I ground the “S” terminal, needle goes to empty, and an open “S” terminal sends the needle past full. So the gauge appears fine. Also, I’m getting 62 ohms from the tan sending wire.

I bought the EFI fuel tank from “Tanks Inc” and the mechanic bought the sending unit from the same company and installed them both. He said he installed the EFI float-type sending unit (compatible with this tank); the one that is 0 to 90 ohm’s (correct for this fuel gauge). Possibly this sending unit is defective. At this point, I guess I have to drop the tank and remove the sending unit to test it; a lot of work being I have to use jack stands.

Any suggestions?
Thank you.

[steve25]

Well seeing as you only have 3 gallons of fuel in the tank, now is the time to drop it and have a look at things, even though doing such does suck!

[Formulas]

see what the ohms rating is on the new sending unit to verify if its the correct one to start with then verify what it actually reads to verify its health
also look to make sure the new unit is grounded properly

stands to reason its the new parts, not in your dash

[george kujanski]

Not a EFI setup, but when I installed my new tank and sender, i took the time to tweak the sender such that the gauge would move slightly off "E" when there was only a few gallons in the tank.

George

[Steve C.]

I doubt it applies to the situation here because of the style (shape) of the tank itself. Although it is stated to be 1" Deeper than stock

But a tid bit for conversation, some aftermarket tanks are shaped so they have more fuel capacity at the top than toward the bottom. Wider at the top and narrower at the bottom.

Ricks '70-'73 design is one of them. I have it installed in my car for the fuel injection system in place where a factory tank would be:

https://rickstanks.com/shop/#!/70-73...gory=140285309

With their aftermarket fuel sender used in conjunction with that tank design the float comes down slower with the larger volume of fuel at the top. As the volume of fuel reduces the float drops faster. Result, when my fuel gauge reads near 1/4 tank it only has a few gallons left inside. if that !


.

[Radman]

Early sending units were a 30 ohm system. At some time the sending units were switched to a 90 ohm system. If you now have a 90 ohm system the gauge will always read more gas than you have. There are two ways to fix it. First get a 30 ohm system. Second add a 20 watt 45 ohm resistor in parallel with the sending unit. One end of the wire at the sending unit signal, the other end to a good ground. There may be a slight error when the tank is full, but 3/4 to 1/4 should be spot on. The empty reading is much more important than the full reading. They all drive much easier than they push.

[Lee]

The TanksInc "float style" sending units, IMHO, SUCK. I've installed a few. CAREFULLY measured & marked per their instructions - go to about 1/3-tank (as read on the gauge), and I'm on the side of the road with NO gas in the tank. Several R&R's to make adjustments... I could get it to read accurate at either FULL or EMPTY, but never both.

I've swapped one car over to their "tubular" sending unit, and also used the tubular on a friend's car with an EFI system - we've both been careful and filled up before pushing our luck, but the tubular seems much more accurate.

Holley has a new "lidar" based system. Looks interesting, but I'm not sure if it is any more accurate than the tubular system.

[JLMounce]

The cheaper float style units aren’t very good in many of the tanks due to how shallow they are. If you have a float style sender I’d replace it with the tube style sender offered by tanks Inc. it’s about 60 bucks more than the standard sender but is better quality and much more accurate.

[flat-bill]

Sounds to me as though you need to bend the float arm to fine tune the full and empty settings. Empty the tank or get the float to the bottom of the tank. Then bend the arm until the gauge matches. Do the same at the full float setting. You may have to trim the length of the float arm. If you don't have it get the installation instructions from the manufacturer.

[jimib]

Originally Posted by Lee

The TanksInc "float style" sending units, IMHO, SUCK. I've installed a few. CAREFULLY measured & marked per their instructions - go to about 1/3-tank (as read on the gauge), and I'm on the side of the road with NO gas in the tank. Several R&R's to make adjustments... I could get it to read accurate at either FULL or EMPTY, but never both.

I've swapped one car over to their "tubular" sending unit, and also used the tubular on a friend's car with an EFI system - we've both been careful and filled up before pushing our luck, but the tubular seems much more accurate.

Holley has a new "lidar" based system. Looks interesting, but I'm not sure if it is any more accurate than the tubular system.

Yeah, the tubular-looking floats are called Floatless Fuel Sending Units sold by Tanks Inc which should match with my Tanks Inc EFI tank.

https://www.tanksinc.com/index.cfm/p...rod/prd346.htm

[OCMDGTO]

X10 on getting the floatless sending unit. There has been a lot written here about them being the one to get. I've been using one for a couple years with success.

[Tom Vaught]

X20 on the float-less sending unit.
ONLY WAY TO GO.

Tom V.