Feeling Gassy

Finally have some time to catch up on some of the projects that I completed at the end of summer this year.  One of my main goals was to get my gauges working reliably and the other was to replace the gas tank.

Gauge Problems:

• Temperature Gauge Pegs at 'H' around 200 degrees
• Fuel Gauge reads 'E' at a half tank of gas
• Oil Pressure Gauge pegs at high upon start-up
• Voltage Gauge reads fine

The first step was to replace the voltage regulator (previous post).  Although everything works now on the cluster, the gauges are sill not reading accurate.

So the next step was to go through and start replacing the sending units.  I picked up an Oil Pressure Sending Unit as well as an Temperature Sending Unit from Mustangs Unlimited.  After installation of these parts, the oil gauge worked perfectly but the temperature gauge was still running too high.  

I was out of ideas for the temperature gauge, so I hit the VMF Message Boards.  Someone mentioned adding some resistance to the wire to bring the gauge down so I went and picked up a 1/2W resistor kit and added a 3.5 ohm resistor to the line.  This brought the gauge down to where it reads 180 degrees around 3/4ths and creeps up to 'H' around the 220 range.  I am now comfortable with both of these gauges and don't feel like I need to freak out when I am sitting in traffic with a temperature gauge pegged at 'H'.  Now if I see that the gauge is pegged at 'H' I better get off the road and let it cool down (hasn't happened yet).

Temperature Sending Unit

Oil Pressure Sending Unit

New Gas Tank

Since I was going to be replacing the fuel sending unit, I decided to replace the tank as well.  It is at least 30 years old (if not the original) and just a good idea.  My guess is the float on the old sending unit has a hole in it that is letting gas get into it and not properly float.  

I picked up a Premium Fuel Tank Kit from CJ Pony Parts.  I picked this kit because the tank comes with a drain plug and it has a brass float sending unit from Scott Drake.  A word of caution though, if you do end up ordering this kit, don't expect to get it anytime soon (the sending unit is the long lead time item).  I ordered it in July and didn't get everything until late August.  

Overall though the install is pretty simple.  Once the tank is drained, removal is just a handful of bolts and screws and the tank slides out of the trunk.  I did end up painting the new tank with a couple coats of rust proof primer and Eastwood's Tank Tone Paint for protection before I installed it.

Finished Product with New Sending Unit

Installation

So I go ahead and get the new tank installed, put in 5 gallons of gas, and fire the car up.  Everything is running, I go to check the gauge and it is reading flat on 'E'.  Are you serious?!?!?  Just my luck I tell you.  So I hit the internets to find out what could have went wrong and troubleshoot the error:

1. There is a bad connection - The connection looked a little corroded so I was wondering if there was a bad connection.  When the wire is grounded, the gauge is supposed to go straight to 'F'.  I ground the wire, and the gauge goes straight to 'F'.  
2. There is a bad ground - I check all the bolts to make sure they are all secure.  I did use some sealant when I installed the new tank, so I used an alligator clip to ground the tank and see if that was the culprit.  Still nothing from the gauge.
3. The Sending Unit is Defective - this is my worst fear.  Now I have to drain the tank again and remove the sending unit.  It works on variable resistance from 0 - 70 ohms.  I bench tested it with my multimeter and it was reading correctly. 

Whelp, I'm lost now.  I have no idea what could be wrong so I decide to just install everything again.  It should be working.  I get everything back together, put in 5 gallons of gas and fire it up.  Except this time I see a little life in the gauge.  It is still reading 'E', but it is not pegged at the bottom.  I decide to run over to the gas station and fill it up. I start the car, and baboom, the gauge goes to 'F'.  It's a freakin' miracle!  Well not really, there was probably just a bad ground somewhere that got fixed when I re-installed everything, but still it works!  I'll take it.

It was a pain, but I got everything working and I am happy with the instrument cluster and the gauges now.

Project Frustration Score:

Due to the problems with the fuel sending unit and gauge, I give this project a 2/5 angry cavemen:

Project Satisfaction Score:

I have peace of mind now knowing that the gauges are reliable and the gas tank is new, but since nothing I did drastically changed how the car works, I give it a 3/5 happy cavemen.

On a final note, I added a passenger side mirror (it's worthless):