I'm installing a '69 Mustang gas tank in my 56F100 and have been told by AutoMeter that if I use the Ford sending unit I will get false readings with their gas gauge. The Mustang tank has the fuel pickup integral with the sending unit and there is not another connection on the tank. Also the AutoMeter sending unit is for top mounting and the Mustang has a side mount sending unit. Does anyone know if there is a way to make the AutoMeter gas gauge and the Ford sending unit compatible electrically?
Or, other suggestions??

Thanks.

 

Tough one...the problem is most aftermarket gauges operate at 240-33 ohms resistance and Ford/Chrysler vehicles gauges operate on 78-10 ohms. I know of no way to make the two compatible. I can offer two options, though neither are going to be what you want. You can buy an aftermarket gas gauge made for a Ford or Chrysler (they are available in most parts houses) and hang it under the dash, or you can take the tank to a shop and have a hole cut in it and mount the Autometer sending unit leaving the Ford sending unit right where it is. One final option would be to hook the gauge up to the Mustang sending unit as is and see what kind of reading you get...if any. If you do get a reading from the Mustang sending unit, my guess is empty will read empty or below empty, but full may only register as 1/3 tank or something like that. If you can live with that, then so be it! Perhaps there's some electrical geniuses on here that know what kind of resistor could be put in place to change the guage to operate on 78-10 ohms, but I don't have a clue

 

I was just checking Autometers website because I am going to run into this also.

In their street rod section, they list gas gauges for all different makes and models.

(0 Ω Empty/30 Ω Full) For most GM vehicles before 1965.


(0 Ω Empty/90 Ω Full) For most GM vehicles from 1965 to present.


(73 Ω Empty/8-12 Ω Full) For most Fords before 1989 and most Chrysler vehicles.

(240 Ω Empty/33 Ω Full) FUEL Sender may be needed, see model 3262.

I wonder why they're saying that when it appears that 73/8-12 would work with the stock sending unit. Are you trying to make a gauge work that you have or are you trying to find one that will work?


Mike

 

Mike-
I had already purchased the Ford Motorsport (AutoMeter) set of gauges before I decided to change gas tanks. Maybe the Ford Motorsport gas gauge only comes in the higher impedence numbers. It appears I will have to modify the tank if I want to have accurate readings on the gas gauge. That means adding a fuel pickup connection and either using the AutoMeter sender in the original side location (don't know if this sender will work in that orientation) or doing as GreatNorthWoods suggested and cutting a new hole to mount the sender in the top of the tank. Not what I anticipated when I decided to change tanks but that is part of the process.

Larry

 

To followup: The more I thought about this the more it bothered me so I tried calling AutoMeter again and got some answers this time. The Ford Motorsport gauges that Ford commissioned AutoMeter to build only come with the 240-33ohm gauges with a matching sending unit per Ford's request. You would think Ford would consider a person might want to use a Ford Motorsport gauge with a Ford sending unit but not so. Only considered to be a streetrod aftermarket/new tank situation. The Ford Motorsport supplied sending unit is only a top mount so it can't be used in the 69 Mustang side connection location. The options, if you want a fairly accurate reading fuel gauge on a 69 Mustang tank and using Ford Motorsport gauges:

1. Cut a new hole in the Mustang tank to locate the top mount sending unit and add a fuel pickup connection. Close up the original sending unit hole on the side of the tank.
2. Send the Ford Motorsport fuel gauge back to AutoMeter and they will modify by mating the Motorsport face to another Ford type fuel gauge that matches the Ford 73-8/12 ohms sender. However, the reading will still be a little off at the mid range of the gauge due to the face indication points being a little different between the different style gauges. Will read accurately for full and empty, just a little off at half way.

Something to keep in mind if you use the Ford Motorsport gauges and the Mustang tank. AutoMeter makes other gauges that work fine. Hope this keeps you out of more trouble than this got me into.

Larry

 

Larry,
I ran into this exact problem about 9 months ago(should have come up on a search on either this forum or the electrical).
I ended up ordering the #1505 Autometer guage with the intention of switching the face myself,although it looks fairly close to the Motorsport guage.I just haven't had the time to do it yet.

Greg

 

Thanks for the reply Greg. I did a search but I think I must be inept when it comes to doing one because I never seem to find what I'm after. Larry

 

Now I understand...... Thanks for explaining, I was getting ready to order the FMS gauges for my 70 mustang tank.

Hope everything works out.

Mike