How To Test a Fuel Sending Unit & Gauge | Old School Way

An old-school approach to quickly diagnose your fuel sending unit and the gauge. Most times, the wiring is bad. Use this video as a reference.
Heres a link to a good universal fuel gauge to use in your test: amzn.to/2xdlQdL

[@faronf2006]

Love this way of testing the sender unit over using the typical ohm meter ...can see exactly what is going on with the fuel gauge when the float is moved up or down . Thanks for posting .

[@elir079]

I wish I saw this video before I bought a new fuel sending unit for my 71 Mustang. Liked the video simple and easy to trouble shoot the fault.

[@williamgrissom9022]

I got a very similar-looking stainless fuel sender for my 1965 Dodge Dart and also bench-tested before installing. It was a bit erratic, so I popped the rheostat cover. The wiper looked a bit loose, so I bent it to contact the slide-wire tighter and then gave a solid signal (10 ohm full to 70 ohm empty as I recall, Ford & GM different). BTW, the slidewire wasn't an actual wire, but more a smooth conductive surface. I also replaced the old thermal 5 V regulator w/ a modern electronic one and tweaked the output voltage to get the level and temp gages reading correctly. To realize that, I had to also tweak the gage pivots and add parallel resistors across the level sender to get "F" to read correctly.

[@shed911cookiesgarage2]

thanks mate, I have a full reading on my old merc and now I know I probably have a bad wire, earth or sender wire. thumbs up man

[@1987lafuente]

Love the video man. I'm having that full on full problem. So, with this video I now know where to start.

[@mick_yarnall3051]

Buddy your a life saver I’m going crazy rn and u just saved me. Keep it up 👍🏻

[@jumpinjojo]

*You’re

[@sidneybolt1099]

This is a brilliant vid. Thanks from the UK!

[@mysteriomarvel933]

Excellent video explanation. I'm actually thinking of making a little mock up of a 1965 Ford F250 custom cab dash guage in my closet with the tailgate and lights encasing it. I open the tailgate and it opens up to a workbench so I can have fun and test individual guage circuits like a science lab for vintage Ford trucks. I'll have functioning switches and pull knows and lights too. That's my project plan anyway.

[@vinny6875]

Sounds interesting I'd like to see it when completed

[@Yellowghost73]

You have it backwards. The pickup tube is at the lowest point in the tank. You would stall at 3/4 tank .

[@f150bft]

Great video. I did notice that you must have something wired backwards. If you oriented the sending unit as it would be in the tank the full position reads empty and empty reads full. The way you are holding the sending unit the the siphon tube would be towards the top of the tank and not pull any fuel. Unless there is some camera trick going on that I'm not aware of. Just an observation. Thanks for the video.

[@MrLike2surf]

great bvideo, Straight to the points and very clear.

[@r0bbiemiller888]

A Vette with a fuel cell,has 2 wires out of the cell which are green yellow and one purple wire out of factory.proper way to wire. I like your vedios much better than the nerds that use the ohm meter. thanks Robbie

[@fernandomartinez5812]

Thanks for the video bud. Very informative.

[@rogerwilcoshirley2270]

Basic but very useful, thanks!

[@mancaveproductions00]

Great stuff thanks

[@davesaam4308]

Excellent instruction without checking ohms.

[@superfuntime3107]

Do you have a source for push on connectors for the post terminals on top of the sending unit ?

[@olliej914]

chasing an issue on my mustang. just found out the foxes have an ivr/resistance wires in the cluster... I rewired my whole 82 gt from ron francis..and after filling up at the gas station im at 3/4 full...tested the sender wire and i think im getting 12v instead of 5v.. sender shows 10 omhs full and probably 70ish empty... howver im picking up 40 ohms when keyed off on that sender wire alone that feeds the cluster..,.. not much to go off these older mustangs. let me know if you have any thoughts. thanks

[@hovlandbound]

Hi Thanks for the video. What is your thought if the gauge always shows empty? Wiring to the battery? or the ground to the gauge? Thanks!!

[@luksurias]

Thank you very much.

[@DIABLO_4_Tester_Sacramento]

hi, i replaced fuel pump but sensor installed from the old one. Now at full tank it shows 80%...

[@chrissummerland7012]

I have a 1983 toyota corolla KE70 i bought 2 mounths ago when i first had it i noticed there was a problem with the fuel gage it was reading over a quarter of a tank after i have been driving for twentey minuts i stopped at my loceal store i notist the guage started moving up past the half way mark and then stopped and then slowley moved back down into the correct reading whice wss quarter of a tank so in thought i probabley need a new sending unit so i replaced that but it still does the same thing when i stop or park or go up a slight slope or slight hill i thing it could be a bad earth wire or plug that connects to the contact of the sender unit needs replacing?

[@witnessmoyo1951]

Well explained

[@gregrenfro2211]

Great video

[@tendoman32]

Is it possible to use that same sending unit for my 1986 honda accord dx

[@markpatterson7070]

Thanks for the video !!!!!!!!!!!!!!

[@javiertrujillo3136]

What do you think my problem is if my gauge works from full to a notch under half tank... but never drops under that mark...i think maybe the float is damaged or hangs up at that mark...should I roll the dice and just replace it? The car is a salvage vehicle 2017 Lexus NX200t but never was hit in the rear.. Thanks in advance

[@deborahwadden3733]

i just bought a new no start ls 04 tranks but no staart power to relAY POWER to fuel pump but im not seeing any power to the sending unit but if ones a signal and ones a ground i guess there shouldnt be power or a fuse

[@paulgeorge9614]

my manual calls for 3ohms full/80ohms empty the replacement unit I received reads 6.5omhs full/82.5 empty will that cause an issue ?

[@endlesssummer3406]

What if guage stays on E? Unplug it, it goes to full.

[@TheLange1175]

I realize this old,but I have the same type of sending unit and the problem I’m having is the needle moves a little and stops. The wire is good and I just changed the sending unit. Any ideas? Possibly the gauge itself?

[@avcomth]

I think all modern cars since at least the 1990s would have the time delay circuitry in between the sender and the indicator to prevent the gauge from swinging wildly with the movement of the car seen in older models.

[@xchadderbox]

How many volts are going back to the fuel sending unit?

[@hisyst]

Very good

[@azzazel_99]

Does the yellow wire have power on it?

[@markfeuerherdt2338]

I have a 1980 CJ5. My speedo cluster has the fuel gauge built into it. When I start the jeep, gauge needle goes from below E to on the E. Won't go past. I have about 10 gallons in it. Has a poly tank. My temp gauge works good. I never really had a full tank. It was in the shop for about a year. I am going to de fuel the tank and drop it. I will see how the ground on the sending unit is. I never calibrated the sending unit before I dropped it in. Then again the speedo is made by Crown, and there is probably a quality control issue. Any help will be great. I got a new sending unit and I calibrated it with my multimeter. When I pull the sending unit out, I will check it with a multimeter to see if it need s adjusting, thanks!

[@TheThirdWheel618]

I have a 69 F250 my aux tank is like that .....I have 2 tanks only my in cab tank only has 1 wire to the sending unit and it has a grounding tab on the sender that's the one I'm having a issue with funny the gauges run on 6 v I tested the voltage on the sending unit

[@gbertostorage1575]

How do you calibrate?

[@jeremykillebrew5232]

Solid video. My scenario is it stays on half

[@omarstephenson8967]

Thanks

[@BeezNeezz]

What if it is reading Empty and doesn’t move?

[@Archifx]

Bad gauge

[@CreatorCade]

Oh thank goodness I was loosing my mind over this.

[@billwilliams6338]

FIX IT NOW }} \\ The Temperature gauge needs a "resistance value" or a Voltage? to be applied to the temperature gauge to see the needle moving from C to F? When I disconnect the temperature sending unit/temperature sensor can't I just use a variable resistor potentiometer and watch the temp gauge need moving from C to F? the temp sending unit/temp sensor is a thermistor which is a variable resistance But i dont' know what my temperature gauge is wanting a resistance and a voltage or just only a resistance in order to move that temp gauge needle from C to F?

[@Outlawthis]

my fuel gauge only has 2 places to connect wires on the back, is there supposed to be 3?

[@theincredibleediblekrausewich]

How is it that it reads empty when the float is furthest away from the sock? Shouldn't that be the full position?

[@jimdandy849]

Correct. He has it upside down - the sock would be at the bottom of the tank. Apparently, his gauge is reading reverse resistance possibly for a different sending unit. 1969 Mustang sending unit is 73 ohms empty, 10 ohms full.

[@dewholdingsllc1050]

What’s the spec for resistance on the ford pick up unit? It you know? I don’t want to buy a aftermarket fuel gauge. I have a multi meter for testing components like this. Should be a range of resistance as you move float lever. Nobody makes a aftermarket pickup unit for full size Ford. (Aftermarket units are an inch short so screen is not at the bottom of the tank. ) just sayin.

[@ivanalcivar5251]

It was a good video

[@roster2423]

Is there there a simple way to test it so i dont have to drop the gas tank? I have a 94 f150 5.0 4x4.

[@nicholas4514]

Not expecting a reply based on age of video. I am working on an 87 plymouth and I'm reading empty on the guage even though I have a full tank.

[@Banjoguy55]

Seems like your testing it upside down. Wouldn't your screen be in the lowest part of the tank

[@xjrope]

No, it clogs faster

[@shrop]

Nice....

[@tonysantamaria19]

My gauge always shows empty. It is only 4 years old, but it went empty and now doesn't show fuel. Any ideas if this can be fixed?

[@modeljetjuggernaut4864]

I think some setups are reverse where the least resistance is full and high resistance empty. My 69 Dodge is set up like this.

[@robertsnyder4966]

Something in your gauge hook up is backwards. The end of the pickup tube goes to the bottom of the fuel tank. When the float is near the end of the fuel pick up tube, the gauge should read empty. In your video it is reading full.

[@Archifx]

All gauges are different. This one is reverse OHM

[@papergatorzfedducca7998]

Thumbs up!!!

[@thedr4549]

How can this test be accurate when the factory used a pulsed 5V from the instrument voltage regulator?

[@Archifx]

Because I did the test and I’m always accurate

[@dalebecker6583]

To me that seems backward! Screen at bottom of tank to pick up fuel, float would be showing empty if it was next to the screen, right? Float away from screen, it’s full?!

[@thomashogan7272]

I agree. I think he has it backwards and I think he has the wrong gauge for that sending unit. Ford's senders have 10 ohms resistance at full and 75 ohms at empty. I think GM cars are opposite that setup.

[@yevgeniykovalenkov4708]

That is a return line, not a pickup, so everything is correct.

[@Banjoguy55]

@@yevgeniykovalenkov4708 so where is the pickup?

[@jimdandy849]

@@yevgeniykovalenkov4708 Not. It's a pickup with sock/screen. I've had my 1969 mustang since it was new and have dealt with its sending unit over that time. Any vehicles that had return lines during that era were 5/16 inch, and were right next to the 3/8 inch pickup. There is no other place on a mustang fuel tank for a return line. Just look at a photo of a 1967-70 fuel tank and you will see that there are no other openings.

[@jimdandy849]

@@Banjoguy55 He has apparently never been around a vintage Mustang.

[@Eagle127]

180 off !! The float when empty should be closest to the pickup screen.

[@Shawncombat]

Please link fuel sending unit, I cannot find it anywere

[@houstonhotdog5273]

Thats why i keep 2 gal gas can locked in back of truck

[@lesetsamonyama5618]

IF THE UNIT ALWAYS SHOWS EMPTY EVEN IF THE WIRES ARE DISCONECTED

[@michaelkors109]

Power wire came off it went to empty

[@MrThegabbster]

Dah. A. Ya. Sorry