TCS gas level sending unit ??

[andy harwood]

 The gas gauge was not working correctly at purchase, not at all now. Since a new sending unit came with the car, thought I'd install it last week. I seem to not have a spanner to do it properly. Attempted to use a hammer & punch, didn't seem to want to break loose. Before I bent/broke a tab, I stopped until I could get a proper or better tool than I was using.I know I could make something, but thought I'd ask what others have used first.
Any recommendations?
thanks in advance
andyh

[EuropaTC]

Is this the "twist to release" type of sender ? (It might sound silly to ask, but I replaced my tanks years ago and they have a bolted sender)

If so, then I think I'd try soaking in release fluid/paraffin/whatever to try to get into the crevices. I'd imagine the big problem is rust forming against the rubber gasket and jamming the whole thing solid. 

Then I'd make a tool from some 1/8" bar to bear on both lugs and get a proper twist motion,  I'd be concerned the unit is too thin to withstand a punch without getting damaged.  (I'd normally suggest a blowlamp to heat it up, but perhaps you'd like to check your life insurance before starting that one     )

Brian

[andy harwood]

Brian
thanks for the tip.
Yes, it is the twist type, with 3 tabs.
PB blaster and scrounge the scrap metal pile for tool material it is then.
Andyh

[3929R]

On mine I sprayed it with some sort of PB blaster type of stuff (don't remember exactly what), let it set, then tapped it with a hammer and some other close at hand but inappropriate tool.  It came off easily enough that I don't remember the details, sorry.

I wonder if it is your sending unit of the plastic float?

My gauge didn't work either.  To diagnose I first jumped the lead on the sending unit to ground/earth and verified that the gauge read full (key on, I think).  This indicated that the gauge and wiring was good.  Next I took a long stiff wire, bent a J hook on the end, fished it down the filler hole on the tank, gently pulled up the float, and verified that the gauge read full.  This suggested that the sending unit was good but the float likely was bad.  Then I removed the sending unit and found that the clip on the float arm had punctured the plastic float.  I think the plastic may have been degraded by some additive in gas?

I replaced the plastic float with a brass one intended for an old Mustang.  I don't remember exactly which one but I measured my original and compared it to online pictures.  It may have been this, http://www.cjponyparts.com/product.aspx?p=FSUF&utm_source=google&utm_medium=merchant&utm_campaign=shopping  Or just Google, there are many options.... 

If you prefer supporting a Brit parts seller, maybe this? - http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=108849

I bet British plastic floats can be found, but why?

[3929R]

If you replace the sending unit, vs just the float, will you need to calibrate it? 

[EuropaTC]

If you replace the sending unit, vs just the float, will you need to calibrate it?

If you've got the proper sender unit for the gauge, then nope, it's just plug and play. If you're adapting a unit from another car, then you might have to adjust the instrument to reflect full/empty positions correctly.

Although strictly speaking I'm wandering off topic, the last time I replaced mine I did some searching for another resistance unit which matched the gauge. (home-made Al tanks with a bolted in sender fitted back in the late 80s).   

I think the one I bought came from an MGB and the resistances varied between 20 & 200, but I'm hazy on it. However it was just plug & play with the instrument, which was the main requirement, even if it wasn't so simple with the flange.   If anyone is in the position of not being able to get an original unit and needs to find out what the resistance profile is, I'm sure I've got it somewhere on this PC.

[andy harwood]

Thanks for all the helpful tips.
I've not done anything towards replacing the sending unit yet, have to make a tool first.
But - I did check that the gauge actually functioned (thanks for the reminder 3929R).
It does, probably the float, reads empty all the time. Before stopping functioning altogether, would read to 3/4 full, and drop at different rates.
I have installed different gauges, but fuel gauge has same ohm as original (I think), 233E/90F.
Since a new sending unit/float assembly came with car, I'll install it(and hope it works correctly).
thanks,
andyh

[EuropaTC]

Andy,

Before you pull out the old sender, you could check that the replacement operates the dash gauge simply by hooking it up with crocodile clip leads to the engine bay wiring and just move the float up and down ?   At least that way you'll know for certain if it's a match.

I went looking through my files but couldn't find the graph I had when I did mine. However I did find some more info which may or may not be relevant but still adds to group knowledge on these cars.  From Lotuselan.net I made these notes;

S1, S2, and S3 models have 0 Empty to 90 ohms Full sending units. S4 and Sprint models have 6 ohms Empty to 77 ohms Full sending units. However the US S4 had 253 ohms Empty to 25 ohms Full OEM sender unit.  (is that the wrong way round ? hmmm)

The S4 would be comparative era to the S2/TC Europa and so it depends exactly what gauge was fitted to these models I guess, the point is that Lotus used both and apparently weren't consistent across model ranges. 

Incidentally, when mine failed it also failed "empty". When I removed it I found the resistance coil had broken at the top connection, so it was quite fixable with a soldering iron. I didn't bother because I had a new one, but if your new unit doesn't match the gauge then maybe that will turn out to be a further option.

Brian

[andy harwood]

Brian,
I'd not thought the unit that came with car may not be correct. Just assumed, and I know where that gets me. I'll hook it up and see if it works correctly.
If its not correct, I'll probably just live with no gauge for a while - Ive got a pair of  aluminum tanks coming and a top mount 233/90 sending unit.
While under the car, looked at the original tank mounting points. The top forward attachment on both tanks appears may pose a accessibility issue. Not looking forward to the change out.
Thanks for the helpful tips.
andyh

[andy harwood]

the sending unit i have is a Smiths.

A hand written note in the box states:
Lotus #054N6008
Smiths #TBS1514-001
250 ohm empty, 22 ohm full.

Part # on sending unit is TBS1514/005
I did attach sending unit with leads, and it functions.

GGLC web site cross reference page lists
S1- Smiths #TBS1514-000
S2- Smiths #TBS1514-001
TC SP- Smiths #TBS1514-005

So, maybe it will work correctly, cool.

thanks
andyh

[CLW]

Just as info, when Chris (TheKid#9) and I were looking for a TC Special fuel sender we couldn't find one. So we bought a couple of S2 ones that were rusted and cheap. I did this on a hunch that the first part of the serial number is the actual sender and the last part has something to do with the arm length. I think I was right. After disassembling both and a little cleaning, both worked with the TC dash gauge. I then took one of them and bent the rod around so that it provided about 15 inches of swing, and shortened it so it didn't hit the edge of the tank as the S2 unit must be longer. We then took it to a radiator shop and had the vent plugged. I left one alone for future use or sale! see pictures.

[EuropaTC]

Buying something "close" on a hunch and then getting it to work, now that just goes to show how inventive Lotus owners can be when restoring their cars !

I feel I can now confess that when I previously mentioned fitting a MGB unit in mine, the arm was all wrong as well. It was far too short so I ended up brazing on an extension and bending it so it matched the tank profile. What I usually call "class one bodging"....   

Definitely O/T now, and hence apologies to Andy. 

CLW - if you're Chris's dad, then congratulations on the work you've done with Chris on his car,  a project to be proud of in many senses.  And if this is your first post, then 

Brian

[CLW]

Yep, I'm the Dad in this almost two year adventure in restoration! It has been a lot of work. I used to play golf on the weekend!!

Chris and I have worked together well, only occasionally does one of us get frustrated. Usually its me when I do something and figure out I should have done another thing first. Chris is a great kid and I am proud of his maturity level with cars. A couple of incidents with the Mustang he previously had helped that! Also his realization of how delicate the Europa is has been a learning experience. He will respect that I'm sure. It will be a weekend car at most anyway, now that he has an M100 (which by the way is a great everyday Lotus).

Back to the sender. What I did was bend the little stops on the unit also until we got 0 to Full on the gauge with the arm swing. Those stops are what I think controls the ohm reading as the windings are capable of sending the correct signal to the fuel gauge. When we first plugged in the sender outside the car after bending the arm around for swing I only got about a half to 3/4 full gauge. So I just modified the stop to give full. Similar adjustment at the low end.

We are getting closer everyday having it finished. Still have a brake pedal I'm not to happy about, and will bleed brakes again today. The only part we are missing now is the spoiler. We started gluing the headliner in yesterday. That was fun! Interior work, brakes and door insides today and next weekend.
Clure

[Grumblebuns]

The removal tool for the sending unit can be made from a 2" piece of plastic or iron  pipe. Plastic is simpler to make. Notch 3 slots 120* apart around the circumference deep enough for the tool to bottom out on the retaining ring. If the slots were cut out accurately enough, you'll have contact on all three tabs on the ring and the tool will allow you to push down as you turn the ring.

To repair cracks in the plastic float, I used a soldering iron the melt the plastic and seal the cracks. It worked. It beats using a wine bottle cork that I found on one of the sending units that I removed this past summer on a spare TC tank.   

[andy harwood]

thanks for the tip and photo.
I'll use this info to make a wrench.
All the help and suggestions have been great!
andyh