Does the fuel gauge in your...
Does the fuel gauge in your Mopar always read empty, or worse yet, does your car starve for fuel during acceleration? This month we’ll show you some common problems to Mopar fuel pickups and how to fix them cheap!
Even though recycling is popular, it seems like our society has gotten used to throwing certain things away instead of repairing or rebuilding them. Electronics is a good example, as items such as telephones and television sets would be repaired in the past if they stopped working. Now we simply get rid of the phone or TV and get the latest model. Our cars are no exception to this, especially since nearly every part to rebuild your Mopar is available these days. But what about the parts that aren’t reproduced or readily available? We were recently faced with a fuel pickup and sending unit issue in our ’69 Newport, and checked around for a new pickup and sending unit. Instead of paying a premium for a new or N.O.S. unit, however, we decided to simply repair ours and save some money.
At the heart of a fuel system is the fuel pickup and sending unit, located in the car’s fuel tank. While the fuel pickup sounds simple, it’s really comprised of two separate systems, one to deliver fuel to the engine and the other to provide an electrical resistance to the fuel gauge. On the fuel delivery side, the pickup is basically a tube that is centered in the bottom of the tank, with a filter or “sock” at the end to strain any major contaminants from the fuel. On the sending unit side, a potentiometer is located in the tank, attached to an arm with a brass float that provides varying resistance (between 10 and 70 ohms for most Chryslers) depending on the level of fuel in the tank.
So long as the car’s fuel is kept clean and free from contaminants or water vapor, these components generally last a long time. But if the car has sat idle, especially with an empty tank and in a humid climate like ours, moisture can accumulate in the tank, causing corrosion to the pickup and fuel sending unit, rendering the fuel gauge inoperable or a loss of fuel pressure to the engine. While our problems weren’t bad enough to starve the engine for fuel, we did want to see if we could get the fuel gauge of our Newport to work and check the general condition of our sending unit and fuel pickup.
1 It’s easiest to access...
1 It’s easiest to access the fuel sending unit and pickup with the tank out of the car, but you can also perform the task with the tank still installed. The fuel sending unit and pickup assembly is held in the tank with a locking ring. If you don’t have the proper ring removal tool, the ring can be rotated counter-clockwise with a screwdriver to remove the unit, or clockwise to lock it in place. New locking rings are available from companies like Year One, but rarely go bad.
Held in by a locking ring, the sending unit is easiest to remove with the tank out of the car, but can be removed with the tank installed if necessary. Having pulled the tank to make some floor repairs in the Newport, we decided it was a good time to clean and flush the tank, and check out fuel sending unit as well. After pulling our unit from the tank, three problems were apparent. First, the rubber gasket between the sending unit and the tank tore during removal, necessitating replacement. Next, the fuel pickup filter, or sock, was nonexistent, having disintegrated in the tank sometime during the past 40-plus years. And third, the brass float of our fuel sending unit had corroded to the point of having holes in it, explaining why our fuel gauge always read empty (the float was full of fuel).
Fortunately, a quick check of our sending unit with a multi-meter verified proper electrical resistance, so we simply logged on to Year One’s website (yearone.com) and ordered a new seal, float, and filter for about $25. Compared to the $194.50 price of an N.O.S. pickup, this is a bargain and the easy repairs will get our Chrysler’s fuel system and fuel gauge working properly.
2 With the unit removed from...
2 With the unit removed from the tank, we noticed three separate problems. The seal was torn, the brass float was corroded through and didn’t float at all, and the filter sock was nonexistent. Fortunately, Year One has replacement parts for all these items and we quickly ordered them from their website.
3 The new brass float from...
3 The new brass float from Year One is identical to the factory unit, but doesn’t have the time-created holes, so it will actually float and provide a proper fuel gauge indication. The potentiometers in Chrysler sending units rarely go bad, and inoperative fuel gauges can usually be blamed on a sunken float.
4 What was left of our filter...
4 What was left of our filter sock was lying in the bottom of our fuel tank. The new sock (top) fits in place of the factory unit and provides a pre-filter to keep major contaminants out of the fuel system.
5 The factory seal always...
5 The factory seal always tears when the sending unit is removed, so we ordered a new seal from Year One. At less than three bucks, it’s nice to know we won’t have any leaks once we install our rebuilt sending unit and fuel pickup.
6 Using a multimeter, we...
6 Using a multimeter, we checked the resistance of our sending unit by moving the float through its travel. Factory specs are between 10 and 70 ohms, and our unit’s resistance varied from 8.9 ohms to 69.2 ohms, which is as close as these units were from the factory. To test the unit, place one lead of an ohm gauge on the wire connection for the fuel gauge, the other lead on the housing plate, and move the float from empty to full.
7 After thoroughly cleaning...
7 After thoroughly cleaning and inspecting our sending unit and pickup, we installed the new parts from Year One by simply snapping them in place of the originals. Instead of paying close to $200 for an N.O..S part, our fuel pickup and sending unit were serviceable for about $25 in parts from Year One.