Plymouth Owners Club

I have a 41 Plymouth that has been modified (with an alternator) to a 12 volt electrical system. All works well except for the fuel gauge which works for a year or so and then quits. I have to replace the component that was installed to reduce 12volts to 6 volts. I'm quite sure that it is'nt robust enough. I believe it's a resistor type...the size of a thick quarter mounted on a heatsink with two leads on it. 12 volts in and 6 volts out. Does anybody know of anything easy to install...ready to go that I could replace this with? I saw a Borg Warner VR1 on line.
http://compare.ebay.com/like/120914625535 var=lv&ltyp=AllFixedPriceItemTypes&var=sbar&_lwgsi=y&cbt=y

Would this work?

Thanks, Bob

Interesting question.  I have the same issue with my 52 Plymouth.
At first I used a Runts reducer, which is close to what you show.
Then I went to a transistor voltage regulator.  A small transistor you can buy at Radio Shack.
Now it acting up again.  After about three years.
I started thinking, my year has electric wiper motor, that I am using a larger ceramic voltage reducer.  Works great for the wipers. 
I am going to tap off of that this time for the fuel gauge, and see how things go.  The only issue I can see is it may act up if the wipers are on, but that is rare anyway.

Wish you luck on yours.

Most fuel gauge work on measuring resistance along a coil of wire as an arm travels along that coil with the level of fuel. As such most of them are voltage neutral, meaning they will sent their resistance message regardless of 12v or 6v. 

The most common problem with fuel senders is a poor ground.  Run a jumper wire from the sender to a good clean ground in the trunk floor and in 90% of the cases your gauge will thak you by actually indicating the level of fuel inthe tank.

By the way this is another one of those posts that should not be discussed here as it represents talking about an unapproved modification from stock factory provided components.

I can't tell if your joking or not.  If you are, it's hard to read with the bright bold red.
If you not, just shoot me, I don't want to spend the rest of my life in cyber jail.

If I sign up 5 new members do I have to tell them that if they discuss unapproved modifications their money isn't wanted here, or do I take their money and run. Some members have an attitude that makes it hard to be part of this club.

For the '52, it should have a single wire sender and a relatively simple and voltage insensitive dash unit. I wouldn't want to run 12v through it as may burn it out, but within reason you can feed it a fairly wide range of voltages and it should read okay. I'd measure the system resistance when the tank is full (minimum resistance in the sender). What ever that resistance is, buy a resistor of the same value at your electronics shop and wire it between the power feed to the gauge and the gauge. That should drop the voltage by about half from 12v to 6v. You will want to size it to dissipate the power properly. So if, for example, you find you need a 22 ohm resistor (because you measured around 20 ohms with a full tank) then you'll have a system resistance of around 40 ohms. With 12v your current would be (12*12)/40 or 3.6 watts. For that I'd be looking at maybe a 5 watt rating.

If I recall correctly, the '41 will have a two wire sending unit and a thermostatically operated dash unit. I would guess that it will take more power to run that type of gas gauge than the more common single wire setup. And because of its construction, I am not sure if you can simply measure the resistance through the system to get a estimate of its power draw. But you ought to be able to do roughly the same thing with a voltage dropping resistor.

If you want to get fancier, you could fab up or buy a 5v (close enough to 6v) regulated power supply that uses a 12v input. I am guessing that a couple amp output would be sufficient. As long as you are working with a negative ground, 12v to 5v supplies should be pretty cheap as they are widely used in the PC industry. You'll want to find one in a form factor that can be easily hidden so that plym_46 can't see it. :)

You guys apparently missed that my tongue was firmly planted in my cheek with my finishing comments.  It was incas mr FourDoor was looking.

Kinda goes along with this thread

http://plymouthbulletin.com/smf/index.php?topic=3041.msg15990#msg15990 (ftp://http://plymouthbulletin.com/smf/index.php?topic=3041.msg15990#msg15990)

Like  I stated, your attitude is is a problem , I justed looked at the POC application form on the POC web site, and there was no wording in the form that stated your position that we are not welcomed becaues our cars are less than 100% original. In fact the club's site says all cars are welcome. I did enjoy the beautiful pictures and the article on R C Downs and his father in the Plymouth Bulletin, they had some great pictures of his car, even though his wheels are not original. Not everyone shares your views. I'm glad I have not paid my dues yet, if i'm not wellcomed here, its ok by me, but your one opinion does not make the club, it might win a car show, but it does not make the club.

Deep breath everybody,  it's crusiin weather.

I saw the tongue in cheek Ply 46, I got a chuckle out of it anyhow. Thanks for a bit of humor once in a while. This is a great site, even if everyone does not have the same veiws, more power to them, and us. This is America.. lol and I like a good discussion, either way, Hot Rod or Total restoration, or like mine . . an old restoration from the 60s, suit me, for now..
Take care all,
SD Glenn

Hey Mrr41, I believe you are unfamiliar with my stand, apparently you did not review the thread I posted, nor have you read my posts from the past.  As an owner of a modified Plymouth, I merely take an opportunity now and then to take a poke at some of the FROM THE FACTORY provincialism that arises when folks may stray to the road of the non factory part as a solution for enjoying their cars by actually driving them.

Glad to hear that you had me going, I enjoy reading about your knowledge of plymouths and will look forward to future posts by you, enjoy driving your plymouth, Best wishes.

Thanks for all the technical info, good options.......

Original post included this question: "Does anybody know of anything easy to install...ready to go that I could replace this with? I saw a Borg Warner VR1 on line.

http://compare.ebay.com/like/120914625535 var=lv&ltyp=AllFixedPriceItemTypes&var=sbar&_lwgsi=y&cbt=y

Would this work?"

I appreciate all the input...and the joking too but I was hoping to get an answer to this question above...Do you think this Borg Warner VR1  would work?

Thanks...Bob

Sorry, yes it will work.  The gauge is looking for 6 volts. 
Be aware if the sender in the tank was ever replaced, chances are the replacement are not as good as the original.
Most of us who have worked on these realize the indicated fuel level is a general idea only.

The other options listed in this thread would also work.

Quote from: jd2ksilver on June 03, 2012, 12:43:46 AMMost of us who have worked on these realize the indicated fuel level is a general idea only.

Not just on the old cars. My 2004 Toyota has some weird setup that is wildly pessimistic on the amount of fuel remaining. At least it seems pessimistic as a fill when it claims I'm on fumes only takes 7 gallons in a tank rated for around 11. Or maybe the fuel cell bladder has changed in some way where it no longer will hold 11 gallons. I haven't been willing to try and run it empty to see what the real situation is. Looking at the forums for that car they call it a "guess gauge" rather than a "gas gauge".

I've owned two '36 Plymouths; a P-2 4 door touring sedan 1969-90, and the present convertible 1990-now. The gas gauge was fine in the sedan; the one in the ragtop never worked, despite several attempts to repair it.

So I just write the mileage in a small notebook when I fill up, and fill it up again every 100 miles, to be on the safe side. That has worked for me since 1990; as long as the odometer works, I'm OK.

Pat O'Connor

Quote from: jd2ksilver on June 03, 2012, 12:43:46 AM
Sorry, yes it will work.  The gauge is looking for 6 volts.  
Be aware if the sender in the tank was ever replaced, chances are the replacement are not as good as the original.
Most of us who have worked on these realize the indicated fuel level is a general idea only.

The other options listed in this thread would also work.

Thank you John, I'll try to acquire a BW VR1 on e-bay...looks like a quick/cheap fix. Right now I'm using 4 AA batteries with a switch in line to check on my fuel level periodically. It works very well for now...until I get something permanent. I must have an original sender and float in my gas tank because it's very accurate and smooth and has virtually no fluctations whatsoever when starting/stopping/turning. Thank you all for your input.

Bob

I never thought of using the 4 AA batteries.  A great troubleshooting tool, thanks for that.