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Tech Area => General Buick Tech => Topic started by: Hill1430 on September 29 2023, 12:19:23 AM

Title: Fuel Gauge Not Reading Correctly
Post by: Hill1430 on September 29 2023, 12:19:23 AM

I have installed a Racetronix 255 LPH fuel pump and sending unit. When the tank is full it reads almost 3/4 full. Do I need to drop the tank and play with the float, or am I missing something?

Title: Re: Fuel Gauge Not Reading Correctly
Post by: xracerx13 on September 29 2023, 09:40:17 AM

Did you get the right float. Theres 2 kinds. 1 for digital dash and 1 for analog dash?
Just askin :D

Title: Re: Fuel Gauge Not Reading Correctly
Post by: Steve Wood on September 29 2023, 09:48:00 AM

I guess I would verify that you had the right fuel sender for your dash first.  If you have a digital dash, it uses a different resistance sender than the standard  sending unit which is 0-90 ohms.    I believe the digital dash was 120 ohms.

At one time racetronix sold a different resistor for the sending unit if you had a digital dash.  You had to remove the 0-90 "rheostat" and install the 0-120 as I recall.

If you have the standard unit and the standard analog dash, the trick was to pull the cluster and clean up the post on the back of the fuel gauge where the connector from the sending unit goes.  That often fixed the problem.

When the tank is full, you can disconnect the connector to the sending unit at the tank and read the resistance to see if it reads the correct resistance at the tank.  Should be either 90 or 120 depending upon the installed sender.  If it reads lower than whichever one is low, you can drop the tank, pull the sender and see what the resistance reads when you hold the float all the way up as in a full tank.

That is all that I can think of at the moment

Title: Re: Fuel Gauge Not Reading Correctly
Post by: Hill1430 on September 29 2023, 01:18:50 PM

I have double checked and I do have the correct one for an analog dash. I will follow your advice and check the dash and the resistance. Thank you both!

Title: Re: Fuel Gauge Not Reading Correctly
Post by: Steve Wood on September 29 2023, 06:20:06 PM

Make sure it reads 90 ohms when the tank is full.

Title: Re: Fuel Gauge Not Reading Correctly
Post by: Hill1430 on September 30 2023, 10:44:34 PM

I will do that. Thanks

Title: Re: Fuel Gauge Not Reading Correctly
Post by: Steve Wood on September 30 2023, 11:56:24 PM

If it does, make sure the tank has a good ground to the body sheet metal also.

Title: Re: Fuel Gauge Not Reading Correctly
Post by: Hill1430 on October 09 2023, 12:12:42 AM

Shyer filling the tank the sending unit showed 90.7 ohms. I pulled the fuel gauge and cleaned the 3 pins. Now it reads as it should. Thank you for the advice.

Title: Re: Fuel Gauge Not Reading Correctly
Post by: Steve Wood on October 09 2023, 09:13:08 AM

Happy to see something worked LOL

On to something else

Title: Re: Fuel Gauge Not Reading Correctly
Post by: Hill1430 on October 09 2023, 09:35:41 PM

Right