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Installing A Fuel Gauge and Sender

Installing a Fuel Gauge and Sender

By:  Jim Clark,  the Hot Rod M.D.

 

   Modern high-mpg cars have large fuel tanks and experience extended-range between fill-ups.  Old hot rods with small fuel tanks and big gas-guzzling engines require more frequent fuel stops.  This makes an accurate fuel gauge more important when embarking on the open road.  So this often overlooked device takes on a more important role.

   Fuel gauges seem like a simple device that we would assume to be standard across most all vehicle lines.  Actually they vary widely from one make of vehicle to the other.  This table of offerings from a fuel gauge sender supplier illustrates how they differ from one make to the next.
 
 Which Fuel Tank Sender Do You Really Have?
0-30 Ohms (GM Type '64 and earlier)
0-90 Ohms (GM Type '66 and later)
 75-10 Ohms (Ford Type '86 and earlier)
 16-158 Ohms (Ford Type '87 and later)
 90-0 Ohms (Toyota and Nissan '85 and later)
 240-33 Ohms (Standard Aftermarket)
 
 
Therefore it is important to use the gauge and matching sender in your project.
   
     My original set of VDO Cockpit series of gauges made it necessary to adapt the supplied sender to my original ’32 Ford gas tank.  Only one hole for the sender is supplied in an original tank, unlike the fine reproduction tanks that come with two.  The second hole in them is for the fuel pickup or electric pump in fuel-injected cars.
   
     I had to rotate the flange slightly to allow for drilling holes to match the six-hole pattern on my tank.  A new gasket was made and the unit cut-down to account for the depth of the tank.  Most sending units have a float assembly that has to be modified to fit the depth of the vehicles tank.
   
     There is a new alternative now available that you might consider if you are still in the process of selecting a gauge set.  It is a new type of floatless fuel sender from Classic Instruments. This fuel level sender is designed to work in vented tanks with depths greater than 6-1/2 inches.  Sender must be mounted perpendicular (not at an angle) from the top of the tank.  Available in 240-33 & 0-90 ohm resistance ranges.  You simply cut it to length and calibrate it for your application.  Just make sure that it is compatible with your gauge.
 
 
New floatless fuel sender from Classic Instruments.
 
 
The following photo sequence shows the steps necessary for the installation of my fuel sender and routing of fuel lines on my roadster.  They should be similar for your project.
 
 
This is a typical fuel tank sending unit with an adjustable float level.  Cardboard marked with top and bottom of tank indicated shows where uncut sender would fit in tank.
 
 
 
 
 
Float for sender comes with a long rod that has to be cut to length once the sender is shortened to proper length for this tank.
 
 
 
 
 
 
Stock ’32 Ford fuel tank has a flange with a six-hole pattern.  The standard pattern for most modern fuel tank sending unit flanges and universal senders is five holes.
VDO offers an adapter to allow the standard 5-hole pattern to be on early Ford six-hole tanks from 1935 to 1956. Fuel Sender Adapter Flange for Fords 1935-1956: # 226902. My ’32 Ford tank has a smaller 6-hole flange.
 
 
 
 
 

 

I had to use the sending unit supplied with my VDO fuel gauge because it registers empty at 10 ohms and full at 180 ohms, the same as new VDO gauge senders. The standard aftermarket senders now measure the fuel capacity at 33 ohms empty and 240 ohms at full. Bolt pattern was rotated slightly to match the six-hole pattern on my stock '32 tank. Large hole is for fuel pickup tube.

 

 

 

Fuel pickup tube was fabricated by silver-soldering a length of 3/8th fuel line to a 3/8th pipe thread / hose barb 90° fitting.  Was cut to length and fitted with Ford in-tank nylon mesh filter from van / F-100 pickup (not shown).

 

 

 

Installing a Fuel Sender

Paper pattern was made to match the new hole-alignment on flange; it is then transferred to cork gasket material.

 

 

 

 

Installing a fuel sender

If you don’t have a gasket hole punch then a piece of steel fuel line of the correct size can be used to cut the holes in the cork gasket.  Some other gasket materials may be a little tougher to do this with.

 

 

 

Sender was cut to a little less than half of the fuel tank depth and a new hole drilled and tapped for the clamping bracket.

 

 

 

 

 

Cut down sender is adjusted to half the depth of the fuel tank and the clamps tightened.  Center of float pivot point should be the reference for half the depth.

 

 

 

 

Float is installed in our mockup of the tank and positioned just off the bottom of the tank.

 

 

 

 

Float is then swung through full travel to determine that it ends its travel just below the top of the tank.

 

 

 

 

Once the travel of the float through its full swing has been determined the rod can be cut to length and the screw tightened on the pivot shaft.

 

 

 

 

Sender unit is installed into the tank using the new gasket and appropriate hardware.

 

 

 

 

Next the fuel pickup tube is screwed into the sender flange.

 

 

 

 

The finished unit provides for the signal to the fuel gauge and site for the fuel pickup.

 

 

 

 

 

Short section of 3/8-inch fuel hose connects tank to steel line routed along the inside face of the right frame rail.

 

 

 

 

Three-eights inch steel fuel line passes over the rear crossmember and is secured with insulated clamps.

 

 

 

Fuel line continues along the frame rail taking care not to route it too close to any exhaust components.  I chose to use a continuous piece of line because I was able do so while the body was off.  Some applications might need to join more than one length of line at strategic points to allow for routing in close quarters.

 

 

 

A double-female flared union was used to join the 45° flared end of the fuel line to a 90° angle 3/8-inch flare / hose fitting.  Larger insulated clamp will secure it to the frame rail.
 
 
 
 
 

Here is the finished end in the engine compartment where a short fuel hose will complete the connection from the fuel tank to the fuel pump.

 

 

   Wiring for the gauge chosen will vary depending on the application.  Instructions for this are usually included with the gauge package.  Your fuel gauge may seem like a minor item until you find yourself out on the open road in the middle of nowhere and without a fuel stop insight.  Then you may learn to appreciate this often-overlooked item.

 
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