Fuel Sender & Guage Test

[Deleted User]

I am in need a "shade-tree mechanic" testing procedure to check my fuel guage and sending unit before I resort to dropping the tank and putting in a "new" sending unit.



I know how much fuel is in the tank as it was measured going in. I get nothing on the guage. The wiring looks good in the dash and as much as I can see of it under the car and in the trunk.



My thoughts are that the sending unit is rusted or stuck as this car did set with much fuel in the tank for a long time.



I do have a multi meter and a length of wire.



Thank you in advance.

Ol racer

There are probably many ways to test system but I first test the gauge by grounding the wire to the tank for a moment. If the gauge moves its good, if not the gauge is bad.



The Fuel sender & float needs to be out to move up & down comparing with the gas gauge movement...

hudson1948

You don't have to drop the tank to get at the sending unit. I've taken out plenty without taking the tank down. Sometimes the sending unit needs a ground wire from one of the screw holes on the sender to somewhere under the car. But try gronding the sender wire first to see if the gauge goes up.

hdsn49

In many cases, its the float on the sending unit that goes bad. You can get a replacement float from a Ford dealer. I don't remember the number. I changed the float on both of my 49's and that solved the problem. I'm sure someone on the forum will supply you with the correct number.

Unknown

OK guys , start from square one,use the meter and be sure you have voltage at the unit. Then be sure the unit is grounded good,no rust in conections. If it don't work then pull the unit and check it. Could be the float or the unit needs cleaning or replaced. I've had some looked like impossable that cleaned up and worked fine. To check the gauge ground the hot wire to chassis, gauge should flop all the way to full if OK. I've taken them apart and cleaned them up to work also but they are delicate. Bud

[Deleted User]

37 Terraplane#2 wrote:

OK guys , start from square one,use the meter and be sure you have voltage at the unit. Then be sure the unit is grounded good,no rust in connections. If it don't work then pull the unit and check it. Could be the float or the unit needs cleaning or replaced. I've had some looked like impossible that cleaned up and worked fine. To check the gauge ground the hot wire to chassis, gauge should flop all the way to full if OK. I've taken them apart and cleaned them up to work also but they are delicate. Bud

OK...So



Step One) Open the dash gauge panel, disconnect the feed wire from sending unit to input on gauge, connect a temp wire from ground to input on gauge.



Step Two) Turn key ON for only a short period of time to look at gauge.



If gauge is OK, it will go to FULL. If not it is bad.



Step Three) If Gauge is Good, install 14 gauge wire from one Sending unit screw to clean point on chassis, again check Gauge.



Step Four) Using extra wire and multi meter, check feed wire. Should be Zero Ohms.



Step Five) Pull sending unit to check for "clean" and holes in float.

Unknown

I'm wondering how many guages do you see go bad compared to sending units. My suspicions are that its usually a sending unit....am I right?

[Deleted User]

Jimalberta wrote:

I'm wondering how many guages do you see go bad compared to sending units. My suspicions are that its usually a sending unit....am I right?

From what I have read on this forum, I would agree. I just wanted a procedure that would work as the book procedure was written as if a person had a known working unit with which to test.

Unknown

Hi I am looking at replacing my fuel gauge but the problem I have is that the car (52 Pacemaker) is in the shop and I don't have access to pull the sending unit out of the tank and I need to find out what the ohm readings for the gauge would be.



I know there are different readings depending on your car make. For example 50's Chevs - 0 ohms EMPTY to 30 ohms FULL and others are 270 ohms EMPTY and 33 ohms full.



Does anyone at all know what my Hudson would be I can't find it anywhere and really need to get it sorted as I am having work done on the dash and looking to put new round gauges in.



Thanks,

Adam

[Deleted User]

Some years ago I replaced the float in my 50 Pacemaker Deluxe's! fuel tank. The old float had corroded in two and became a "sink" instead of a float thus giving an empty indication on the dash gauge. The replacement float was smaller than the Hudson one and consequently sometimes gives an erroneous indication. If you have a bad float make sure you replace it with one that's of similar size.

mars55

Here is official procedure from the Hudson Body Service Manual 1948 - 1954.

dougson

When I removed the old sender from my tank I found that the "flexible" copper connector band was broken. To be sure I would remove the sender and replace it with a new Ford unit. If it's 50 years old, it probably should be replaced anyway. Which brings up a question, how durable are the gas and temperature gauges in stepdowns?