The Lotus Grand Tourers

I've checked - A082N6044F is the earlier (pre 85) Esprit originated gauge, A089N6011F is the later (post 85) Excel gauge.

A082N6011F would be the result of some bizarre genetic experiment

Interesting!! That certainly gives me slightly more confidence that my wacky ohm readings aren't necessarily so wacky if the gauge is rather unique.
The Tech asked me to check one or two readings once more, and then i'll hopefully get the sender ordered tomorrow.

Hi Bill,

Id also be interested in seeing how you get on with this. My sender unit has gone and I need to replace. If I can get one done to the same calibration as yours and it is a direct fit, that may be the best way to go

Cheers

Andrew

Will do, item is ordered. They are making it now. Biggest issue I see is the company is small and only took my order over the phone. Could be a pita for non u.s. buyers to work with them. But will let you know how it goes.

Sender arrived today. I will move forward with the installation this weekend based on my initial testing!!! Hooray!

The unit requires a switchable 12V+ in addition to ground and the send wire. (See para 2 for alarm wire). I can pick the +12V ignition up off the flow lock. I think I can get away without a relay but might drop a fuse in there just to be safe. With the 12V+, Ground and send attached, the gauge comes to life and works as expected. It even does a cool "startup" of moving to full and then sliding back to the actual level. The 120 second smoothing is evident. I placed the sender from out of a tank to a full tank and found it moving the gauge from an empty position to Full very slowly and makes it's way to full within the 2 minutes. Since it has no memory, if I cut the power (turn off ignition and back on) it immediately finds the correct reading after doing its quick startup sequence. So at a filling station I will have real time readings when I start the car back up. Very happy with these results!!!!

ALARM: I quickly noted the low fuel light alarm isn't coming on by simply connecting the alarm contact to GRN/ORG. I tested and found the low fuel module illuminates after 15-20 seconds with the current sender's alarm wire GRN/ORG taken to ground. (the low fuel light has worked all along even though the fuel level of the sender was never working).
The centroid sender instructions read as follows: "The alarm output switches to ground, A DC Load which requires .3A or less can be connected to this output, with the far side of the load connected to ignition voltage."
What I'll have to do is Connect the control side of a relay between the +12V voltage coming to the sender and the alarm output which is Ground (-) when alarming. Thus, the alarm signal will simply activate a relay. The load side of the relay will short the GRN/ORG to Ground on the original wiring which will invoke the Low Fuel light in 15-20 seconds using the existing module in the dash. Tested, the concept works. Whew!

So a little extra electrical work to get it in, but the results will be a fully functioning fuel gauge with accurate readings across the range of the gauge and a little high tech appearance on a gauge when the ignition comes on.

Now it's Time to get wrenching and soldering while trying not to blow myself up!!!!

Update: Got stalled a little hunting down a fuel filter - not sure why I thought these specific Mann f 65/1 filters would be common place in the states!!! For now, the old one is going back in, fortunately, it looked pretty good. The bowl needed a good wiping out of surface sediment but the filter wasn't impacted. The tank filter looked really clean and was way bigger than I imagined at 3" long or so. I'm also replacing the non SU fuel pump and going back to OEM since I have this all apart. However, I realized late tonight that the fittings from the previous pump don't line up with my fuel lines exactly. Going to have to resolve that in the morning, probably just going to take out the hard line between the pump and filter and go with push on connectors and a flexible hose.

The tank mounting bolts are also getting replaced. The wheel well side (outside) was in bad shape, fortunately they came apart as intended with a lot of elbow grease but didn't shear off or require cutting or anything stupid.

Lastly, the 5 bolts that held the original VDO Sender in place are too short for the centroid product. I purchased 5 bolts that were about 3/8" longer. They did the trick.

Here's a dumb 1 minute video of the dash "working" https://youtu.be/uSBbQ0Nj6aw
I have another 6 minute vid showing the trunk and wiring etc, showing everything mentioned above: https://youtu.be/bUKfTwYITxs

Now I've heard your voice and seen your YouTube presentation it's like I know you a little better!

I fitted a new 'pointless' electronic version of the SU pump last year ..are you fitting the same?

Also I have the aftermarket 'anti-slosh' module designed and sold by a forum member fitted (intended for the original tank sender) to stop the fuel gauge bouncing at low levels and it stops the fuel low level light from flashing too.

Will your new sender be 'anti-slosh' by default?

"Now I've heard your voice...." (And my disgusting American accent!!!) LoL

To he honest, I'm not certain on the Pump, but I suspect it's the original design as it's whichever one SJ provides?? "FUEL PUMP (original SU)" per their website.

on the anti-slosh, that was my whole reasoning for going to the dip-type sender and this one specifically. Dip senders have no moving parts (popular with boat owners) and the sloshing fuel in the tank doesn't impact their readings as dramatically, further this one has a 120 second smoothing programmed in to it. That's why the gauge needle moves so slowly. It's an all in one solution. Further, it's programmable. If i wanted 30 seconds smoothing, I could send it back and have it changed - I could have the ohm mapping changed as well for any reading between E and F at 1/8th increments. Hopefully one day they'll make one that is end user programmable, but the company is small and just getting off the ground.
This specific brand was the only dip type sender I could find that also integrated a low fuel alarm (which can also be programmed as a High fuel alarm (prevents overfill) and also a Low and High alarm).

Oh, total price was $88.00 (US dollars) Shipped to the US. (63 quid at today's exchange rate)

Phantasm wrote:"Now I've heard your voice...." (And my disgusting American accent!!!) LoL

To he honest, I'm not certain on the Pump, but I suspect it's the original design as it's whichever one SJ provides?? "FUEL PUMP (original SU)" per their website.

on the anti-slosh, that was my whole reasoning for going to the dip-type sender and this one specifically. Dip senders have no moving parts (popular with boat owners) and the sloshing fuel in the tank doesn't impact their readings as dramatically, further this one has a 120 second smoothing programmed in to it. That's why the gauge needle moves so slowly. It's an all in one solution. Further, it's programmable. If i wanted 30 seconds smoothing, I could send it back and have it changed - I could have the ohm mapping changed as well for any reading between E and F at 1/8th increments. Hopefully one day they'll make one that is end user programmable, but the company is small and just getting off the ground.
This specific brand was the only dip type sender I could find that also integrated a low fuel alarm (which can also be programmed as a High fuel alarm (prevents overfill) and also a Low and High alarm).

Oh, total price was $88.00 (US dollars) Shipped to the US. (63 quid at today's exchange rate)

Now I see!

Nothing wrong with your accent! But I am jealous that you live in a warm place!

The sender is fully installed. Everything appears to be working correctly.

The only issue I have now is that the fuel level in the tank (which remained unchanged) was triggering the original VDO Low Fuel alarm to go off. I have exactly 300 miles on this tank and at roughly 20 mpg should have about 15 U.S. gallons of the 17.7 US capacity consumed.

The new sender is reading a 1/4 tank and the alarm hasn't been triggered yet (it's programmed for 1/8 tank or 12.5% fuel remaining - so not too surprising). But, I'm curious how little fuel I'll actually have before the alarm triggers and I see a near empty reading. Once it does alarm, I'll fill the tank and be able to see how empty it truly was. Otherwise, I now know that at a 1/4 tank, it is soon time to fill up per the original equipment.

So, I'm off to go drive the car around with an extra 2 gallon container in the trunk just in case I somehow run out of fuel before the sender reads I should!!

Sidebar: The SU Fuel pump compared to the aftermarket that was in there have distinctively different sounds when working. Honestly, the SU sounds stronger and takes less time to charge the system, glad I swapped them out but still have a viable fallback in a pinch.

Hopefully the final update!!!

SO I went for a cruise. 21 miles later I went from 1/4 tank to 1/8 tank with the gauge slowly sliding down the whole time and then the low fuel light came on. Fortunately, I was less than a mile from a filling station and tanked up. Total Full (nozzle auto shot off and then I top it off again) took 14.8 Gallons (U.S.) of the 17.7 gal capacity. So, easily 3 gallons of reserve and 21.5 mpg on this tank. That yields a 60 mile range after the light comes on and a 380 mile range overall.

Side benefit: the Fuel pump, which I noted sounded stronger above, also improved that hesitation I mentioned in a different thread at 1800-2000 even more to the point it's negligible and probably just my imagination now. Had a great drive today at 78 lovely degrees Fahrenheit and sunny skies.

A STUPID ANECDOTE:
Early yesterday, I left the ignition on all day after turning the car on to put the window up to clean the glass. That night, I found a nearly flat battery, so I popped the charger on overnight and disconnected the battery.
I went to take the car out this morning, pulled the charger off the now fully charged battery and it kinda started then died, then really wouldn't start, just cranked. I was pretty sure it was being starved of fuel. Of course I just messed with the whole fuel system, so I had a few choice words - it worked great yesterday!!!

I noted when I first turned on the ignition the fuel pump barely pumped - like two pumps. I was thinking that the flow lock wasn't working... Checked power connections, all good, not knowing how to test the flow lock, I Started to go look at the fuel pump. Pulled the carpet and loosened the metal shield and the pump went mad pumping fuel (Ignition was still on to test power). I'm thinking, okay -that's good, right?!? The new pump hadn't failed and the flow lock is working. but how was the metal shield coming off a solution?!?

Cause: The soft line fuel line I had to install with the new pump was getting pinched by the metal cover that fits between the battery and pump. So, I re-positioned the fuel pump bracket about 15 degree inward and now there is no fouling. I was really glad it was a free fix after all the work I did the days prior!!

I think a lot of us have found themselves chasing tails when trouble-shooting!

When I get too high and mighty with the wife she just says "gearbox" to put me in my place!

Miles from home, I diagnosed a 'noise' as gearbox failure. Hired a car to go fetch a spare box from home -got a local garage to fit it. Drove off the forecourt -noise still present! It was a driveshaft u/j!!

Follow up. After a 4 tanks of fuel I noted the gauge was barely moving (it worked great the first 2-3 tanks). But I was at half a tank consumed was still reading just below full. it was reading slightly less than when the tank was full, but marginally. Went back and forth with the technician testing stuff etc. Ended up pulling the tank to check for blockages and if the thing would actually read Empty when removed. It didn't read Empty, it read 7/8 tank and did not set off the alarm. Something went wackado in the programming.
The tech told me how to do a factory reset with it removed (it can also be done with a full tank but didn't want to fill it up and not be able to pull the tank so did the empty reset instead this time). It now appears to be working normally again. He's not entirely certain what caused the issue, but the device has some interesting methodology for sensing when it's been refilled and is also sensitive to Ethanol 10% gas vs straight gas. So I'm learning a few things about it. If it weren't quirky, it wouldn't belong in a Lotus right!? So, It's not bullet proof yet. They have a new software update available and asked if I wanted a replacement sender. I told him to hold off and see how this goes for a few months. If it happens again, then I'll swap them out.

-I'll keep you posted as things progress. hopefully without issues. If it happens again, I'll attempt the full tank factory reset, at least that can be done without removing the tank.
BTW, I'm getting really good and pulling it and reinstalling it. Less than 10 minutes!

Quick question - slightly off topic, but I thought that I would ask here rather than start a new thread.

Is it possible to change the sender unit (original to original) without having to remove the fuel tank? I found a blog online that suggested that it was possible to just loosen the two retaining bolts either side and ease it back a little, but there were many more details than that. If someone has managed to do this, I would be interested to hear a little more.

Thanks

Andrew