B4B Fuel gauge momentarily erratic, now only showing Empty

[Bobacuda]

This one is causing me to scratch my head.  The gauge was working (within reason) until a few days ago, then it acted irratically, an now only reads E.

I get 6 V all the way to the sending unit.

I pulled the sending unit and it appears to be working.  Additional grounding did not help. 

Before I fight the short wires and mechanical connections behind the gauge cluster, any thoughts on what else to try?

 

[B1B Keven]

Take one wire off of the the back of the fuel gauge.

Take an ohm reading across the two posts.

You're looking for something in the 40-60 ohm range.

If it's infinite, you've got a broken wire in the windings.

I've got extra gauges if needed.

Edited June 2, 2023 by B1B Keven

[Merle Coggins]

While you’re back there, check the resistance of the sender wire to chassis ground. You should get somewhere between 10 and 90 ohms, depending on the level of the tank. If that’s an open circuit that would account for your “E” reading and you’ll have to diagnose the sender or the wire going to it. Temporarily ground out the sender terminal at the back of the gauge wit the key on. The needle should go to “F” quickly. If it doesn’t you have a faulty gauge. 

[Bobacuda]

I checked the fuel gauge using both Ken & Merle's testing methods.  It appears my fuel gauge is busted.  Great... I'm trying to get the truck ready for the local July 4th parade and associated car showings.

 

Ken - please PM me with info on another gauge and the cost.  It will have to be sent to Comfort, TX  78013.  Look forward to hearing from you.

Bob

[B1B Keven]

11 hours ago, Bobacuda said:

I checked the fuel gauge using both Ken & Merle's testing methods.  It appears my fuel gauge is busted.  Great... I'm trying to get the truck ready for the local July 4th parade and associated car showings.

 

Ken - please PM me with info on another gauge and the cost.  It will have to be sent to Comfort, TX  78013.  Look forward to hearing from you.

Bob

It's Keven, really.

[Bobacuda]

And that's what happens when I use my cell phone rather than the computer - the klutz in me really comes out.

Sorry about that Kevin.

Bob

[Bobacuda]

Got the replacement fuel gauge from Kevin, then spent several hours contorting to get far enough under the dash to disconnect the oil pressure line and make sure that I did not break the heat gauge line and replaced the faulty gauge.  The fuel gauge is once again functioning. (Thanks again, Kevin)

 

What better way to spend a 100 F day with 80% humidity?