The Ford Barn

einstein · 10-11-2019, 12:45 PM

I just put in a new sending/fuel pump unit drove 100 miles and the gage still says full.( History) 1940 Ford Sedan,1990 5.0 HO,all Mustang underneath. Someone put in a 1987 Aerostar sending unit. I have put in new Autometer gauges and a Classic Instruments fuel link. My problem is the sending unit is still reading 158 ohms which is telling the gauge that the tank is still full. I checked the float operation and ohms before installing. HELP

40cpe · 10-11-2019, 08:32 PM

You might already know it, but the gauge and sending unit have to match. The gauge advertisement will tell the ohms required from the sending unit. If you have done that, excuse the post.

Daves55Sedan · 10-12-2019, 10:47 PM

Some of the modern sending units have an adjustable float arm. You need to know the depth of the fuel tank first. For deep tanks, the float arm can be adjusted so that the float is farther away from the fulcrum. For shallow tanks, the float arm needs to be pushed inward closer to the fulcrum.
Now, if the gas tank sits at a slant normally, there is a whole nother problem, because you will run out of gas when the level goes down to where the end of the pickup tube is (often in the middle of the tank), yet you may have 3 or 4 gallons in the tank. This needs to be taken into consideration when adjusting the float arm.

5851a · 10-13-2019, 12:12 PM

Have you tried calibrating the fuel link. I believe it has half a dozen presets. Try calling classic instruments.

einstein · 10-13-2019, 03:04 PM

The fuel link is fine have been in touch with classic the sender is putting out 158 ohms which is telling the gauge that the tank is full

poolplayer1 · 10-14-2019, 11:08 AM

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Did you try putting a meter on the sender to make sure that the ohms are being varied as you raise and lower the float arm,for example from 10 ohms to 158 ohms.
Just a thought.

einstein · 10-15-2019, 08:49 AM

yes i did

JeffB2 · 10-16-2019, 08:10 AM

Some tech tips here: https://www.tanksinc.com/index.cfm/p...cat/cat159.htm

5851a · 10-16-2019, 04:21 PM

That is a head scratcher, you should have used between 4 and 5 gallons. What tank is in the car the 40? Any chance that the depth would be greater than a Aerostar and effect the float staying up longer?

10-11-2019, 12:45 PM	#1
einstein Member Join Date: May 2011 Location: Michigan Posts: 63	Gas Sending Unit I just put in a new sending/fuel pump unit drove 100 miles and the gage still says full.( History) 1940 Ford Sedan,1990 5.0 HO,all Mustang underneath. Someone put in a 1987 Aerostar sending unit. I have put in new Autometer gauges and a Classic Instruments fuel link. My problem is the sending unit is still reading 158 ohms which is telling the gauge that the tank is still full. I checked the float operation and ohms before installing. HELP

10-11-2019, 08:32 PM	#2
40cpe Senior Member Join Date: May 2010 Location: Star, MS Posts: 4,024	Re: Gas Sending Unit You might already know it, but the gauge and sending unit have to match. The gauge advertisement will tell the ohms required from the sending unit. If you have done that, excuse the post.

10-12-2019, 10:47 PM	#3
Daves55Sedan Senior Member Join Date: May 2010 Location: Granite City, Illinois Posts: 3,008	Re: Gas Sending Unit Some of the modern sending units have an adjustable float arm. You need to know the depth of the fuel tank first. For deep tanks, the float arm can be adjusted so that the float is farther away from the fulcrum. For shallow tanks, the float arm needs to be pushed inward closer to the fulcrum. Now, if the gas tank sits at a slant normally, there is a whole nother problem, because you will run out of gas when the level goes down to where the end of the pickup tube is (often in the middle of the tank), yet you may have 3 or 4 gallons in the tank. This needs to be taken into consideration when adjusting the float arm.

10-13-2019, 12:12 PM	#4
5851a Senior Member Join Date: Oct 2014 Location: NE Iowa Posts: 1,663	Re: Gas Sending Unit Have you tried calibrating the fuel link. I believe it has half a dozen presets. Try calling classic instruments.

10-13-2019, 03:04 PM	#5
einstein Member Join Date: May 2011 Location: Michigan Posts: 63	Re: Gas Sending Unit The fuel link is fine have been in touch with classic the sender is putting out 158 ohms which is telling the gauge that the tank is full

10-14-2019, 11:08 AM	#6
poolplayer1 Senior Member Join Date: Sep 2015 Posts: 399	Re: Gas Sending Unit Sponsored Links (Register now to hide all advertisements) Did you try putting a meter on the sender to make sure that the ohms are being varied as you raise and lower the float arm,for example from 10 ohms to 158 ohms. Just a thought.

10-15-2019, 08:49 AM	#7
einstein Member Join Date: May 2011 Location: Michigan Posts: 63	Re: Gas Sending Unit yes i did

10-16-2019, 08:10 AM	#8
JeffB2 Senior Member Join Date: May 2010 Location: Phoenix,AZ Posts: 1,417	Re: Gas Sending Unit Some tech tips here: https://www.tanksinc.com/index.cfm/p...cat/cat159.htm

10-16-2019, 04:21 PM	#9
5851a Senior Member Join Date: Oct 2014 Location: NE Iowa Posts: 1,663	Re: Gas Sending Unit That is a head scratcher, you should have used between 4 and 5 gallons. What tank is in the car the 40? Any chance that the depth would be greater than a Aerostar and effect the float staying up longer?

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