It’s about time!

[Jim Roach]

Well after about eight years I’ve decided that 2020 is the year I’m going to get my 52 back on the road. The first thing I did was to get a new battery. I got it hooked up, jumped in the seat, turned the key and the first thing I noticed was my gas gage pegged to the far right full position. The gas tank is not full. This just doesn’t seem right so I turned the key off and sat down to ask everyone their thoughts. Any help is greatly appreciated. 

[Tooljunkie]

Not sure on how the sender and gauge react with voltage/ground. 
first check is wiring condition. 
next is  battery cables connected properly. 6 volt or 12?

[Jim Roach]

It’s still 6v. I installed the battery the same as the previous one. I was thinking the same thing about having the battery installed incorrectly but double checking it seems correct given the different sizes of the terminals and the previous battery orientation. Everything worked fine the last time it was running. 

[Merle Coggins]

The gauge has 2 electro-magnetic coils inside that move the needle. One has constant voltage and pulls the needle to Empty. The other is connected to the tank sensor, which is a variable resistor. When the tank is low the resistance is high, which makes the second electro-magnet weak. The constant magnet pulls the needle to the Empty side. When the tank is full the resistance of the sensor is low, so the sensor side electro-magnet is stronger and pulls the needle to the Full side. 

 

There are 2 possible reasons that make the needle peg to full as soon as the key is on. 

1. The wire to the tank sensor, or the sensor itself, is shorted to ground. Remove the sensor wire from the back of the gauge and check continuity to ground. It shouldn’t be less than 10 ohms (with a full tank). If you tank is closer to empty you should see up to 75-90 ohms. If. You have close to 0 ohms you have a short to ground somewhere. 

2. The ground for the gauge is bad so the constant electro-magnet can’t pull to “E”. The metal back of the fuel gauge must be in contact with the mounting stud/nut to pass ground to the gauge panel, which in turn grounds though contact with the dash/cab. Check for continuity between the gauge back plate and a good chassis ground. 

[ggdad1951]

bad gas sender isn't likely to cause an issue in safety, just annoyance.

[JBNeal]

additional information - Fuel Gauge Operation and Troubleshooting 

[Jim Roach]

Currently working on the manifolds. The intake has a fine threaded hole on top toward the rear of the engine. Can anyone tell me what it’s for?

[JBNeal]

Vac.port for vac.wipers

[Merle Coggins]

Yup... Should be 1/8" (or 1/4") NPT. You can just put a pipe plug in there to seal it up, if you don't need it for your wipers. Or use that port to connect up a wolf whistle... ?

Edited March 12, 2020 by Merle Coggins

[Brent B3B]

I used that port to hook up my vacuum gauge to assist in timing the engine 

[tom'sB2B]

On 2/3/2020 at 5:18 PM, Jim Roach said:

Well after about eight years I’ve decided that 2020 is the year I’m going to get my 52 back on the road. The first thing I did was to get a new battery. I got it hooked up, jumped in the seat, turned the key and the first thing I noticed was my gas gage pegged to the far right full position. The gas tank is not full. This just doesn’t seem right so I turned the key off and sat down to ask everyone their thoughts. Any help is greatly appreciated. 

I'm having the same symptoms with my gauge. I tested the sending unit by hooking it up to a gauge on another vehicle and found that the sending unit works fine and the gauge is faulty. Not sure I if it's something that is fixable or if I need a new gauge

[Merle Coggins]

32 minutes ago, tom'sB2B said:

I'm having the same symptoms with my gauge. I tested the sending unit by hooking it up to a gauge on another vehicle and found that the sending unit works fine and the gauge is faulty. Not sure I if it's something that is fixable or if I need a new gauge

 

I went through this issue recently with Kris Bolstad's truck, Eddie. It turned out that the fuel gauge was not getting a good ground to the gauge panel and cab. This causes constant coil to NOT pull the needle to "E". The variable coil, that connects to the sender, always wins and pulls the needle to "F" regardless of the sender resistance. The 2 mounting screws for the fuel gauge had insulators under the screw head. Once we figured it out Kris removed the insulators so that the screws would ground the gauge back plate to the gauge panel and all was good from then on.

Edited March 12, 2020 by Merle Coggins

[tom'sB2B]

10 hours ago, Merle Coggins said:

 

I went through this issue recently with Kris Bolstad's truck, Eddie. It turned out that the fuel gauge was not getting a good ground to the gauge panel and cab. This causes constant coil to NOT pull the needle to "E". The variable coil, that connects to the sender, always wins and pulls the needle to "F" regardless of the sender resistance. The 2 mounting screws for the fuel gauge had insulators under the screw head. Once we figured it out Kris removed the insulators so that the screws would ground the gauge back plate to the gauge panel and all was good from then on.

I was so excited to go home and check things out. I knew that one attachment screws did not have the insulator. No luck! I 

Sorry to highjack the thread. Jim, put pipe plug in it and then use it to adjust your timing

With a vacuum gauge.

 

[Jim Roach]

No problem Tom. This information will be helpful too.