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onyerleft

Replacing fuel sending unit on '55 Clipper

Not too shy to talk

When my 1955 Clipper Super started stalling on the road a few months ago, I read about potential rust holes in the gas tank pickup line here:

packardinfo.com/xoops/html/modules/newbb ... um=3&post_id=210310#forumpost210310

Since the tank had some corrosion outside, I thought I would start by taking a look inside. NOTE: didn't happen to me, but take seriously the potential for a drained gas tank to explode when sparks from a drill or other tool ignites fumes inside - have the tank professionally steamed at a radiator shop first.

With the tank removed it was a good time to replace the fuel sending unit, which was working erratically (stalling was due to other issues). First it was replaced with one described as "1955 Packard Clipper compatible" bought from an online bulk parts depot - mistake. After removing the tank again and draining it, I opted for the '55-'56 Fuel sending unit on the Packard Parts X-Ref page, Ford Part #B7A-9275-F, from dennis-carpenter.com.

Determined to have a gauge which showed full when the tank was full and empty when the tank was empty (too much to ask?), I first bought long test leads from an electronics store to be able to accurately test the sending unit from the driver's seat.

Older sending units typically are rheostats - variable resistors with maximum resistance when the float is down, no resistance when the float is up. When the Ford float was all the way up, however, the tank showed only ? full on the gauge, and because the gauge showed full when I shorted hot to ground I knew the gauge was OK. With some difficulty I was able to bypass resistance in the sending unit by soldering a wire from the rotary switch's final position, then attaching the other end to the sending unit's case (ground) with a tiny bolt.

Mission accomplished. I hope this helps anyone else with an OCD compulsion to have an accurate fuel gauge.

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Posted on: 2019/6/17 12:48

HH56

Re: Replacing fuel sending unit on '55 Clipper

Forum Ambassador

For a long time there were very few Packard senders available (and still are not for many pre 51 models) but after the need became apparent and the xref info to Ford products that some found would work was entered, Kanter had the 51-6 senders repro'd. As far as I know they still have them but since the repro tanks he had done about the same time have run out perhaps senders have too. Maybe James could confirm if they are still available or not.

Problem with the Ford units is the float arm length is apparently different because Ford had several tank capacities and shapes and it is only a specific Ford product that will work. I don't know if the xref details on which sender will work is correct or if those who posted an item did any rework such as you did to make them work.

Packard used King-Seeley thermal gauges in 51-6 and those need an ohm range of approximately 75 empty to 10 full. Some Ford, Chrysler and AMC models used that range too. By going directly to ground I would be worried the gauge heater could burn out but if it is grounded only when the tank is absolutely full maybe not as big a concern. Still, unlike the 0-90 or 0-30 GM ranges their gauges needed or the 100-0 obsolete S-W range used in some pre 50 Packard models 10 ohms was there for a reason.

Posted on: 2019/6/17 13:04

Howard

onyerleft

Re: Replacing fuel sending unit on '55 Clipper

Not too shy to talk

Good information Howard.

The arm length on the Ford unit I used was fine, but I needed to bend it upwards a tad to keep the float off the bottom of the tank, and so it would reach all the way to the top.

Maybe next time I have the tank out (if ever) I'll insert a 10-ohm resistor between my wire and ground.

In the empty position my sender read 130 ohms at full empty, so if the gauge only needs 75 ohms it will read empty when there's still a lot of gas in the tank. When I tested it sitting in the front seat of the car however, it was accurate.

Posted on: 2019/6/17 14:15