Delimas and Decisions 69 CJ Gas Tank

This all started when I ran out of gas with my wife in the jeep, downtown Oceanside around 8pm. Some friendly police officers picked us up and escorted us to the Gas station and back b/c the neighborhood was apparnently too dangerous for us to be walking at that time of night. It took a lot of coaxing to get her to come out in the jeep to begin with, hair in the wind and all, and now this.

Anyway, the fuel gauge read half full but it was empty. I dropped the gas tank, and checked out the sender. It is an aftermarket gauge, installed by PO, and must be a fabricated tank, cuz it doesn't match up with anything I can find in the magazines and web sights. The fuel sending unit was erratic and would sometimes go to empty but mostly half full, then at the full setting it would not quite make it to full. It was sketchy at best and not something I want to continue using. Especially if I am going to get my wife back out with me for another ride.

My dash is pulled right now and I am filling in all the holes from the PO. I have a new Jeep spedo gauge with the gas and temp gauges, purchased from quadratech. I plan to use the gas gauge in the spedo assembly.

Now, what to do about the sending unit??? I cannot find a replacement for the one I have and it probably would not work correctly with the jeep gauge. So I have a between the frame, rear mount, gas tank with an irregular hole in it for the sending unit. I suspect the tank is 15 gallons by the amount of fuel I have taken out of it in this process.

1. Do I purchase a new sending unit and fabricate the gas tank to fit the new sending unit?

2. Do I purchase a new gas tank? Presntly, I cannot find a 69 model for 15 gallons rear mount. Don't know if a 70 model will work, anybody know about these things?

3. Do I purchase an under the seat tank? I don't think my seats will allow for an under the seat tank, so, could mean purchasing new seats as well.

Any thoughts are greatly appreciated. I have to get this jeep running by next Sunday so I need to make a purchase asap to get the part in time.

Crawdaddy

 

I figured it would be confusing. My gas tank now is between the frame in the rear. It has 4 long bolts that secure it to the tub. The bolts go through the tank, or the inside of the tank goes around where the bolts go through. There are cylinders made into the tank to put the bolts through. Washers hold the bolts from coming through the tub and lock nuts and washers on the bottom of the bolts keep the tank snugged up to the bottom of the tub. Does that help any?

 

i think he's got a rear mount, but it shouldn't be available for the 69 model anyway should it?? Boyink has done a rear tank install from a later model cj... i know my '71 came with one stock, and it seems to be a little fdifficult to narrow down the year it was swapped to the rear if i remember correctly, but here's the write up:

http://www.boyink.com/supersizedutch_comments/19_0_9_0_C/

 

Chris,
Thanks for boyink's writeup. He doesn't have a working gas gauge though. I have the equivalent to what he has right now, minus the skid plate. A rear mount gas tank without a working gas gauge. My goal is to have a gas tank with a working gas gauge.

BTW, I am from Kennesaw, Georgia. I graduate North Cobb HS in 1990. Played you guys, Marrietta HS, in football.

 

My jeep is not a daily driver, so when I make a couple of days or running around town or out at the farm, I fill it up. I only have a 10 gallon under the seat tank. Which is new. ANd I just converted over to 12 volts. So I have not spent the time to research and get a new sending unit. I don't want to mess around with the new one and guess if I have hooked it up right. Until I know I have the right one. Frankly the gas tank is one area I am concerned about doing it right. I can just see a shorted wire getting getting into a positive wire. My drivers seat would indeed turn into an ejection seat.

My brother had a 100 mile rule for his jeep. Each 100 miles was fill up time.

For now the peace of mind knowing there is no wires running into my gas tank is ok for me.

 

that tank is a replacement for the 71 model tank, so the guage and sending unit for the 71 "should" work. this sending unit looks somewhat familiar, but mine doesn't work right now either and i don't really want to fix it anytime soon. just trying to show you the "stock" jeep parts that you should be able to find without having to show pictures and have people guess which tank you're talking about...

http://www.jeepdoc.com/catalog/partframe.asp?id=79

ahh, north cobb... i actually live in smryna right next to the old campbell high school for the time being, and went to it while i was in school... class of 99 here, so you didn't play me at least.

 

If it was me, I'd go with a new plastic tank, new sending unit and be done with it. Seems like every time I pull my tank out I wind up with a problem as recently happened. My old tub had a hole cut out just above the sending unit for easy access. I'm debating cutting a hole in this one too. My gauge is all mussed up since I had the tank out this winter. I tested everything before reinstalling and it semmed fine. :evil:

 

A working gas gauge is on my long term list of things to do. I know that the replacement senders available for my tank do not work with the VDO gauge in my dash (bought one and sent it back). I have no idea if my original fuel gauge works. When I got my Jeep, the underseat tank had a "universal" sending unit that someone had a machine shop fab up the correct plate for attaching to the tank. It worked with the aftermarker gauge. I got a new poly tank with sending unit from MTS, and that sender does not work with my aftermarket gauge. It reads the opposite (ie. empty when full), but is not accurate at all as the tank becomes empty.


Bottom line: I have three gas tanks, three sending units, three speedometers with fuel gauge, and 1 aftermarket fuel gauge...........and I still don't have any idea how much gas in in my tank. I am left to speculate why the original gauge was ever disconnected and replaced by another gauge. It would probably work perfect if I knew how to wire it up.

 

If you want a working gas gauge do not use the factory gauge in the speedo, as they are always prone to failure. Autometer makes a gauge that works with the factory rear tank sender. Model #3115 this is a pro comp series, application says Ford/Chrysler, the ohm reading is right. I will be hooking one up after Tellico. Auto meter says it will work and it is also the one that 4WD hardware sells as useable with the stock sender.

 

I was just reading the may 2005 issue of jp magazine and they say that they bought a 15 gallon rear mount tank for cj-5,cj-6 pn-7075 from 4 wheel drive hardware.maybe they have a sending unit for you?

 

I converted my fueltank in my 59cj to the rear frame location. I bought a '72 and swapped the tank and dash with the factory speedo and fuel gauge. Been working ever since.

 

my 69 has the under seat and a rear tank, they use the speedo gauge, I have a toggle switch that changes what tank im using and a manual fuel switch between the seats, it seems to work for me, the rear is a 71 tank and sender.....

 

Thanks for all your input on this guys, I put the gas tank back up under the rear and am dealing with no gauge for now. I am thinking thinking that I will purchase a sender for a 71, see if I can fabricate it to my tank, if that don't work, then purchase a gas tank for a 71...........or I could just buy one of those autometer gauges and see if it works with the sender I have in there now.

None-the-less, you guys deffinately helped me out with some options

 

More infor than you'd ever want to know about guages and sending units....

http://www.vernco.com/sparks/id697.htm

Basically you need to get a sending unit with the same resistance as the gauge. Is it a stock gauge? If it is someone here might know what the resistance should be and just get a sending unit to match.

Good luck. Heaven help me if I ever strand my wife in downtown Oceanside

 

Bob,
That article says it all. I have saved it in my howto section of favorites. I now know 500% more about fuel gauges and senders than I did yesterday.

Now to drop the tank AGAIN and measure the resistance of the sender.

 

My stock sender and gauge work. Guess I am lucky. NOTE: Make sure the sender is grounded or the sender/gauge will never work. I ran a separate ground wire to the sender and secured it with one of the screws that hold the sender to the tank. This was after I rhinolined my tub and couldn't figure why the gauge stopped working.

If there is some rubber/plastic/paper under the tank where it lays on the floor, and the tank and mounting strap are painted, and the floor is painted, where did the Jeep engineers think the sender was going to get a ground???

I also think a poor/intermittent ground is what led to the failure of the gauge in my 83 CJ7 (tub was extremely rusted). Maybe just superstition on my part.

 

15 ohms sticks in what's left of my mind. Wrote it down somewhere. Oh man, I'm gettin like my Dad.

 

sending unit that is in the tank now, full reads 50 ohms, empty reads 180 ohms, roughly on both. Don't know what kind of sender that is but I can't find a gauge anywhere that reads that.

I am thinkning that a universal sender from summit might do the trick. Just need to make sure that it fastens to the tank the same as mine does now.

My gauge will be a stock replacement. Does anybody know what the stock gauges read? I am thinking 0 ohms on full and 90 ohms on empty.