2nd Gen Non-Engine/Transmission Fuel Tank Float - How many of us had to change it because it deteriorated?

[rweis]

If it has enough bouyancy to carry the weight of the arm and itself I do not see why it would not work. Does not have to look pretty (although it does), just has to float. Sometimes we get a little too carried away with looks vs functionality and functionality is THE key.



All said and done, the weight of the OEM float material would probably be more than the weight of the brass in the float. I think the material OEM float uses is due to $$ FIRST and long term functionality second. Even swiveling is probably a secondary issue as long as the float is relatively close to the rheostat arm.



I have been looking at a marine (Tempo) mechanical float for a aux tank and they use a cork or cork like material. I think I will do a carburator float like yours there also so there are no "chunks" that can come off in the future.



Bob Weis

 

[DavidC]

In respect to your resistance values. Installing resistors in parallel will change the overall value such as a 100 ohm paralleled with another 100 ohm will yield a 50 ohm final resistance. It has been quite a few years since I have had to mess around with this and would have to check the formula for the values you would require using the stewart warner rheostat. It would require a resistor installed across the 2 sending unit wires anywhere along the circuit but it sounds like it would work especially since you are looking at reducing the value of the stewart warner.



Dave

 

[DavidC]

Welllllllllll. Sorry guy's, just ran the numbers and it did not come out linear. To reach the 220 ohm from 240 required a 2. 7k resistor in parallel. Problem is to reach the 20 ohm from 35 only required a 50 ohm. Unless somebody has another idea?.



Dave

 

[rweis]

Playing with parallel resistor values:



Equation is (R1*R2)/(R1+R2) which say for the 40 ohm end (full end) is (40*40)/(40+40) which yields 20 ohms just fine.



However at the other end of the rheostat the 240 ohm end (empty end) is (240*40)/(240+40) which yields 34. 29 ohms and is a tad (about 185 ohms) off.



Using a 2700 ohm resistor (that makes the bottom end (empty) accurate) gives the top end (full) number to be (40*2700)/(40+2700) = 39. 42. The bottom end (empty) will then be about (240*2700)/(240+2700) = 220. 41 which will be accurate. The mid point (140*2700)/(140+2700) = 133. 10 which if standard would be 120 (ie 10% low at half tank, about 1/8 tank low ie 1 mark on the fuel gauge).



IF anyone has the rheostat out of the tank set the rheostat at 40 ohms and give us a text discription of where 40 ohms is ie 1" too low?, 1 1/2" too low? from 20 ohms (full). Then set the rheostat at 133 ohms and tell us where that is with respect to mid swing travel (120 ohms would be smack in the middle I think), then where 220 ohms is (which should be exactely right at the lower travel limit).



I think the smaller number is the full reading and the larger number is the empty reading. So we are a some off on the full reading, so what. The float (at least on mine) is under the fluid surface anyway and therefore not accurate. The empty end is the critical end, and it gets more accurate as it gets empty. The "low fuel" light is at the low end (empty) and should be fairly accurate.



All of the above assumes you go with a "industry standard" fuel level of 40 ohms - 240 ohms device.



I went to MakeITMopar.com to check what the cost of just the rheostat and arm and float is. It is $45 + S/H, which in itself is not bad if you do the pin revision to make it last.



So far we have 2 choices:



1. Use DC's rheostat and redo the pin hinge.

2. Use something like a Stewart Warner and parallel a 2700 ohm resistor and accept the full tank error and know it gets more accurate as it gets empty.



The capacitance option will come along as it gets researched.



Interesting,



Bob Weis

 

[rweis]

I did a spreadsheet to see how far off (using the 2700 ohm parallel resistor) a Stewart Warner 40 - 240 ohm (industry standard) would be.



Starting at the full tank. The OEM gauge would read about 9. 5% low or about 1/8th (1 of the gauge markings) low. Full fuel would = 7/8 gauge reading.

Ending at empty tank. The OEM gauge would read exactely on.



The error reduces about . 5% for every 1/8th tank used and the OEM gauge gets more accurate as you go towards empty tank. Which means the "low fuel" MIL would also be accurate.



My OEM rheostat is not that accurate anyway, so I do not see aftermarket level senders as a problem provided you use the 2700 ohm parallel resistor.



The key in using a Stewart Warner unit is the complete adjustability in physical verticle height, rheostat position in verticle height, rheostat arm length, and float type either a synthetic cork or brass float your choice, and significantly better construction of the actual rheostat device. The cost of the Stewart Warner complete unit is about $54, the cost of the DC OEM rheostat and arm and destructable float is about $45.



After analyzing the minimal difference of gauge readings, the quality of the Stewart Warner unit, the total adjustability of the SW unit, the availability of the SW unit, that is the way I am going next time I am inside of the tank sometime within the next week or three weeks.



At that point my fuel canister would be used as the DrawStraw physical attach point and physical mechanical stabilizer to the DrawStraw lower end and the roll over valve holder. Another complete rebuild of a basic system that should have been significantly better designed to start with.



Bob Weis

 

[rweis]

Does anyone have pics of the inside of the fuel tank looking toward the front? I need to see what the inside structure looks like to choose a right hand or a left hand Stewart Warner fuel level sender.



Thanks,



Bob Weis

 

[ILIANBG]

Hi Bob.

Thank you for doing all of this research. It seems there is a solution for the bad design. That Stewart Warner unit could work. Did you say it has to be mounted on the tank itself, with a cut out? Is it possible to just use the syntethic cork and attach it to the OEM float arm?

I can't wait to see your results. I do not have a picture of the tank, My camera was not with me then.

Ilian

 

[rweis]

Stewart Warner makes a BRASS float and a synthetic float. I only found this out last friday at my real auto parts store. The guy that owns it lets me look through his catalog set (about 4 feet wide and current) after hours. I spend several hours a day after work there cruising through the catalogs.



SO, we were trying to get floats from Roberts Manufacturing and they no longer make the 2" round brass floats and we thought we had hit a dead end on that short of having a special one time production run.



EDIT START



I ordered 3 of the RM183's (@$7. 54 but min of $20 for cc order) from Robert Manufacturing to have a float alternative that should fit if the SW float does not fit bouyancy or mechanically wise. Depending on the outcome I should have a couple of spare floats. Will see what works best.



EDIT END



Well, in crusing I found the SW physical components, then found the equation for parallel resistors, then wrote a short spreadsheet that I could change the resistor values in and the spreadsheet would do a complete recalculation to see how to narrow this thing down, that's how we found the 2700 Ohm value.



Then I went back and reread every fuel level catalog page I could find and remember. There the brass float was as an option from SW.



Interestingly enough I am going to put a in bed tank in and I wanted a simple fuel level indicator not necessarily electrical (I am getting tired of running electrical every time I do something). I found that Tempo makes mechanical fuel level indicators for marine applications. I found a mechanical sender that fits my tank (18h x 12w x 60l, 55 gallons, from a local manufacturer of tanks) and ordered it. It came and guess what kind of float it has?, yep identical (except for shape) to the OEM float. I'm puzzled why if it is such a problem for us why is it not a problem for marine diesels? I am really puzzled about that. Maybe DC got the cheapest one they could and bought the lowest quality, I do not know. I am going to put the SW brass float on the mechanical tank gauge though. I will also disect both of them (thoughts of high school biology and frogs ) and see if I can figure out IF there are any differences. There has to be something, but what?



Anyway, I am getting close to "low tank" and will drop the tank and do the refurb of the OEM fuel level indicator to see what that entails, and while I am in there will take pics and measurements to see which SW indicator will fit. This should give us (TDR) two options:

1. refurb the OEM rheostat and put the SW brass float on it.

2. put the whole new SW sender with the brass float in and parallel a resistor



EDIT START



3. what about a 3rd option of put the SW rheostat in, in place of the OEM rheostat. I mean mount the SW rheostat to the OEM fuel canister either where the OEM rheostat is or create a new mounting location on the canister, use the SW brass float, install a 2700 ohm resistor parallel, AND you do not have to cut the tank and get all the benefits of #2 above.



The problem we have with the canister are,

1. fuel pickup which is corrected by the DrawStraw

2. rheostat failure which is corrected by the SW rheostat

3. deterrioating float which is corrected by the SW brass float



You have already fixed #1. You correct the remaining 2 DC design flaws by installing the industrial quality rheostat, and brass float.



Nothing says that the SW rheostat HAS to be on the SW tank fixture, how would it know?



END EDIT



If you wanted to put the SW rheostat and float in the SW frame that would require a cut into the tank. However, just forward of the canister on the 2002 tank there is a step and a mounded into the tank a place to mount the sender (ie thicker tank material, flat, and the tank side is shape formed so that a indicator could be put there and not have any mechanical interfearance from anything. SW has a mounting kit just for this purpose with a backing plate, screws, fuel proof gaskets to mate exactely with their sender which also has its matching plate and a fuel proof gasket. The sandwich of SW indicator, gasket, tank, gasket, backing plate all screwed together should do the trick.



I think the flat mounting location is a carry over from DC using the same gas tank for both diesel and gassers. For gassers there is a tank vent mounted there and also in the top of the tank toward the rear of the tank. However, since diesel does not need the tank vent it is not used but the mounting moulded location is still there. I think this location because you can mount it and get your arm to it to hold wrenches to tighten the mounting screws and nuts. Perfect place to put the SW if you go that way.



Getting closer to "getter done!"



Bob Weis

 

[rweis]

SW parts ordered. Will take 9 business days to get here (I read that as they do not fail very often), and a weekend to install. Should have results by 4/25.



Bob Weis

 

[rweis]

I need so info about the float wire itself on the OEM canister.



HOW BIG in diameter is it? Could it be threaded for 6/32 threads? or for 8/32 threads? I have found a diesel compatiable float that is a poly material, 1 1/2" dia x 3 3/4" length that can accept either 6/32 OR 8/32 threaded rod.



Sure would be nice to just thread the OEM wire and screw a easily obtained float that is diesel compatiable onto it. REALLY SIMPLE if possible.



Bob Weis

 

[DavidC]

It has been a while since I had mine out but I believe it is smaller than a coat hanger. Not even close to a 6/32.



Dave

 

[MLee]

I need so info about the float wire itself on the OEM canister.



HOW BIG in diameter is it? Could it be threaded for 6/32 threads? or for 8/32 threads? I have found a diesel compatiable float that is a poly material, 1 1/2" dia x 3 3/4" length that can accept either 6/32 OR 8/32 threaded rod.



Sure would be nice to just thread the OEM wire and screw a easily obtained float that is diesel compatiable onto it. REALLY SIMPLE if possible.



Bob Weis

The stock wire is 0. 095 or 2mm or 3/32 take your pick of which measurement you like. On the coat wire it might work, its steel and just a hair bigger, @ 1. 01-0. 006 bigger. I made one but did not use it. You could probably use it as a test mule and put threads on it.

[I still partial to like my earlier post with the pictures. ]

Marv.

 

[rweis]

For 3/32 wire:



K&S Engineering makes hobby tools. They have taps and dies in 1-72 size (. 073) that would die the 3/32 and would tap whatever else you use as an intermediate adapter to get to the other end of the adapter to 6/32 or 8/32 to go into the poly float. So that route IS possible. Might also be able to build up the 3/32 OEM arm with brass metal and then smooth it down and use a 6/32 die on it, then use the poly float.



I have a mechanical direct reading fuel level gauge from TEMPO that makes products for marine applications. I am going to use it in my aux bed tank. Anyway, It has the same material float on it that DC has which I am going to change. Just for grins I got my dremmel and got the float off and then tried an 8/32 die on the aluminum float arm of the TEMPO gauge. Die worked perfectly, nice clean well cut threads. The poly float (1 1/2" x 3 1/2") will thread on it just fine, AND it will go through the tank mounting plate opening that is 1 5/8" and that plate is welded onto the tank .



Now, when the Stewart Warner sending unit (resistor, arm, frame) gets here I will check it's arm for the size to see if it is also able to use the 8/32 or 6/32 die on it. I am going to replace the OEM sending unit with the SW sending unit. I think the SW unit will be significantly better made. SW has brass floats also which is what I am going ot use, but it would be interesting to see if the poly float would work as well so we have some choices.



Because I am going to put the poly float on my direct reading mechanical gauge in the aux bed tank, I bought 8 @ poly floats ($20 minimum cc order and the float is like $2. 10 @ and 8 was the least they would let me purchase). Anyway I am going to put one on the aux tank gauge and keep a spare, so if anyone wants some of the other 6 poly floats pm me. They are diesel certified and will take a 6/32 or 8/32 stem. I think they are 1 1/2" x 3 1/2" I think, anyway very close in size to the OEM destructable float we are trying to replace and if we can get the OEM arm up to 6/32 and run a die on it, it should work fine.



Just some more ideas,



Bob Weis



Can't wait till the SW stuff gets here, and the poly floats get here then all the parts and combinations will be available.

 

[rweis]

FYI



Floats arrived this afternoon. Simple poly float that accepts 8/32 or 6/32 screw thread.



I tried them on the Tempo mechanical gauge float arm and they fit perfectly on the threaded 8/32.



SW parts should be here by the end of this week and we should have some options by mid next week (we are going camping this weekend).



Starting to look very good.



Bob Weis

 

[JR2]

Hey guys why not switch to something like one of these
http://shopping.rexmar.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=centroid
No float to deal with. A fellow TDR memeber turned me on to them. He is going to get me the details but it would be easy to contact Centroid directly and get one. He did tell me that centroid set one up to have the same voltages needed for our trucks.

Here is the companies actual website... http://www.centroidproducts.com/

 

[rweis]

I took the float off the Tempo mechanical gauge and replaced it with the poly float. The poly float fit perfectly.



I cut the float from the Tempo mechanical gauge in two pieces. It seems to be made out of a pressed "coke" type material. I am soaking the cut sides in diesel to see what happens. The manufacturing process finished the outside surface with a almost impervious sheen quality. The inside is quite different however. It seems to maybe be porus. Soaking time will tell.



I seems to be the same material as the DC float.



As soon as the SW parts arrive we can get on with "the rest of the story".



Bob Weis

 

[ILIANBG]

Thanks Bob. I can't wait for the news. My new float sending unit is acting up again: it would drop from full to 3/4 empty in minutes, or I would drive more than 400 mi. and still shows almost full. I can't take it any more. I have to drop the tank again and I am not putting an OEM item.

Ilian

 

[rweis]

SW UPDATE:



Auto parts shop called supplier, will be sometime in the next 2 (more) weeks. , oh well, nothing I can do to speed them up or I would.



Bob Weis

 

[Matt42]

SW UPDATE:



Auto parts shop called supplier, will be sometime in the next 2 (more) weeks. , oh well, nothing I can do to speed them up or I would.



Bob Weis

Please, please keep us posted. I have two tanks that insist that I am nearly out of fuel, except right after a fill-up.

 

[rweis]

One of the options we are looking at is the 2" round copper float or the float from a gasser carburerator? Well from the thread about Cummins approving B20:



"What materials are incompatible with biodiesel?



Natural rubber, nitrile and butyl rubber are particularly susceptible to degradation. Also, copper, bronze, brass, tin, lead and zinc can cause deposit formations. The use of these materials and coatings must be avoided for fuel tanks and fuel lines. "



Notice in the list: Also, copper, bronze, brass, tin, lead and zinc can cause deposit formations. The use of these materials and coatings must be avoided for fuel tanks and fuel lines. "



Maybe the copper float and / or the brass swivel is NOT such a good idea. Maybe even the printed copper circuit board the rheostat is made of and the arm of the float rides on may not be such a good idea.



The poly float (which screws directly onto the mechanical aluminum arm that runs the gear on the mechanical gauge) is looking better and better, diesel proof.



Notice nothing about aluminum or steel?



At worse case the Tempo mechanical gauge (aluminum / steel body and arm that has a gear drive to a verticle rotating shaft that has a magnet on it on the inside of the tank that drives the mechanical indicator on the outside of the tank, ie no through the mechanism from inside the tank to outside the tank liquid path) with the "remote reading capsule" (which is actually outside of the tank, and is the "capsule that provides variable voltage based on the position of the magnet) is looking better and better.



Maybe the very very long time to get the copper floats and internal rheostat parts here is "providence" helping us not go down the wrong path.



Something to think about. What do others think about the reference to " copper, bronze, brass, tin, lead and zinc can cause deposit formations. The use of these materials and coatings must be avoided for fuel tanks and fuel lines. "



Bob Weis