Fuel gauge not registering properly

Talk about the E-Type Series 3

Craig Balzer
Posts: 40
Joined: Fri Mar 03, 2017 2:02 am
United States of America

#21 Re: Fuel gauge not registering properly

Post by Craig Balzer » Tue Jul 26, 2022 4:13 pm

You said: "Expansion tank, didn't know about that, i'll investigate."

I extracted mine a while back and took a progression of photos. These many help.

It is located in very upper reaches of the left rear fender just forward of the filler tube. Captions may help.

It was wedged in place very tightly. The adhesive attaching the anti-rattle (?) padding also adhered mine to the inner fender

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Last edited by Craig Balzer on Thu Jul 28, 2022 3:07 am, edited 1 time in total.
Craig Balzer
Colorado Springs, CO, USA
1972 Series III OTS, 4-Speed (soon-to-be a Guy Broad 5-Speed), A/C, CWW

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cunpr
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Great Britain

#22 Re: Fuel gauge not registering properly

Post by cunpr » Wed Jul 27, 2022 10:30 am

Dear Craig,
Thank you, very helpful. that looks like you'd need to remove the main tank before getting to the expansion tank. Any idea where the charcoal filter is?
Regards
Paul C
1973 Series 3 OTS
1964 semi lightweight race car in build
1995 P38 Range Rover, owned from new, LPG
1983 JCB 3CX Sitemaster with sidehammer
1989 Bultaco Frontera Mk 15 370cc
1985 Bultaco Sherpa 199B 325cc

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Craig Balzer
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#23 Re: Fuel gauge not registering properly

Post by Craig Balzer » Wed Jul 27, 2022 7:18 pm

I can't see how you'd extract the expansion tank with the fuel tank in place.

Charcoal canister is on right side of engine compartment attached to the vertical panel of the US passenger footwell secured with a single through-bolt.
It is painted hammertone silver -- I ~think~ the same color as the air filter housings -- but I'm not sure

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Craig Balzer
Colorado Springs, CO, USA
1972 Series III OTS, 4-Speed (soon-to-be a Guy Broad 5-Speed), A/C, CWW

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Jeremy
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Location: West London
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#24 Re: Fuel gauge not registering properly

Post by Jeremy » Thu Jul 28, 2022 9:00 am

Paul, you gotta be the only forum member with a JCB in your car collection, with a sidehammer to boot (whatever that is, it sounds fearsome) :yellow:
Jeremy
1967 S1 4.2 FHC

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cunpr
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#25 Re: Fuel gauge not registering properly

Post by cunpr » Sat Aug 13, 2022 10:06 pm

Dear All,
Thanks for all the info and stuff on the other threads regarding the gauges.
Some feedback, I purchased a new fuel tank sender unit from SNG assuming my original would be the fault but no, both gave linear ohm readings when isolated from the car of approx 20 to 200, full to empty. I then connected them to the car's wiring whilst out of the tank and both resulted in an accurate empty reading on the gauge but with the float in the full position the gauge read no more than half full with either sender, new or old. I checked the instrument voltage regulator and I could see it was only giving 5 to 6 volts before breaking and then reconnecting. So I rigged up a temporary loom with battery voltage into the senders, then through the gauge, then to the cars earth, moving the float position had the gauge reading accurately from full to empty for both senders. However I noticed that the ohmage reading from the original sender seemed to vary despite the float being static. So conclusion is the voltage regulator is duff and the sender is probably on its way out.
So I've fitted the new sender unit and temporarily wired the feed to the gauge from the battery side of the voltage regulator and she seems to be working well. A new (semi conductor type) regulator is on the way.

One other point, I noticed something not noted previously, the gauge has quite a long delay after the float position is changed, presumably due to its being a bimetalic strip device, and this was most noticeable when it was descending, going from fuller to less full. The lag returning to completely empty was minutes or more. This obviously won't be a problem when driving but needs to be allowed for when testing. Presumably this is because the strip has to cool down for it to read lower, and in this heat the cooling down will take longer.
So if you are working with an original gauge allow enough time for the bimetallic strip to respond before deciding whether its working or not.
Regards
Paul C
1973 Series 3 OTS
1964 semi lightweight race car in build
1995 P38 Range Rover, owned from new, LPG
1983 JCB 3CX Sitemaster with sidehammer
1989 Bultaco Frontera Mk 15 370cc
1985 Bultaco Sherpa 199B 325cc

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cunpr
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#26 Re: Fuel gauge not registering properly

Post by cunpr » Sat Aug 13, 2022 10:15 pm

Dear All,
Just seen this from 2010, "You can then use your meter to measure the output voltage and thus deduce the on:off ratio. To change that ratio (and thus the average output voltage), you'll need to adjust the adjustment screw in the base of the unit."
So the instrument voltage regulator can be adjusted? It looked like a sealed unit to me?
Regards
Paul C
1973 Series 3 OTS
1964 semi lightweight race car in build
1995 P38 Range Rover, owned from new, LPG
1983 JCB 3CX Sitemaster with sidehammer
1989 Bultaco Frontera Mk 15 370cc
1985 Bultaco Sherpa 199B 325cc

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cunpr
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#27 Re: Fuel gauge not registering properly

Post by cunpr » Mon Aug 29, 2022 1:13 pm

Dear All,
Fitted the semiconductor voltage regulator and now all the gauges work correctly. Just got to fix the cooling fan switch now.

https://www.ebay.co.uk/itm/254355438991
Regards
Paul C
1973 Series 3 OTS
1964 semi lightweight race car in build
1995 P38 Range Rover, owned from new, LPG
1983 JCB 3CX Sitemaster with sidehammer
1989 Bultaco Frontera Mk 15 370cc
1985 Bultaco Sherpa 199B 325cc

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Paul Buckley
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Location: Northwich, Cheshire
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#28 Re: Fuel gauge not registering properly

Post by Paul Buckley » Mon Aug 29, 2022 8:40 pm

Lovely colour!

Stateside car? I thought that no S3 cars came with wires.
Is it a conversion?
Or am I wrong?
Paul

1972 S3 OTS, 32k mls, a survivor.

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cunpr
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#29 Re: Fuel gauge not registering properly

Post by cunpr » Tue Aug 30, 2022 9:48 am

Paul Buckley wrote:
Mon Aug 29, 2022 8:40 pm
Lovely colour!

Stateside car? I thought that no S3 cars came with wires.
Is it a conversion?
Or am I wrong?
Thank you. Sable brown, cinnamon interior. on paper sounds awful but in the flesh strangely fitting to its lines. Thats the original paint, chrome (except for UK overiders), softtop, leather and carpets.
There seem to be quite a few with wire wheels.
Yes stateside car, according to original invoice wire wheels were a factory fit extra.
Regards
Paul C
1973 Series 3 OTS
1964 semi lightweight race car in build
1995 P38 Range Rover, owned from new, LPG
1983 JCB 3CX Sitemaster with sidehammer
1989 Bultaco Frontera Mk 15 370cc
1985 Bultaco Sherpa 199B 325cc

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jagwit
Posts: 595
Joined: Thu Oct 18, 2012 6:52 am
Location: Pretoria
South Africa

#30 Re: Fuel gauge not registering properly

Post by jagwit » Tue Aug 30, 2022 2:50 pm

cunpr wrote:
Sat Aug 13, 2022 10:15 pm
Dear All,
Just seen this from 2010, "You can then use your meter to measure the output voltage and thus deduce the on:off ratio. To change that ratio (and thus the average output voltage), you'll need to adjust the adjustment screw in the base of the unit."
So the instrument voltage regulator can be adjusted? It looked like a sealed unit to me?
In that statement regarding "using your meter", it would be most important to specify WHAT meter, or otherwise HOW the meter is to be used. A typical digital Volt meter (set to DC) is likely to appear most confused, measuring "12V"and then nothing, "12V" and then nothing etc as if the probes are not making good contact.

Here is a higly relevant post: viewtopic.php?p=35094#p35094
Best Regards
Philip
Jag: 72 S3 XKE, 73 S3 XKE OTS, 80 XJS (Megasquirt + 5sp manual O/D)
Jensen: 74 Interceptor (EFI by Megasquirt + O/D 4sp auto)
Chev: 59 Apache std, 70 C10 (350V8, 700R4)

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cunpr
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#31 Re: Fuel gauge not registering properly

Post by cunpr » Thu Sep 01, 2022 3:11 pm

cunpr wrote:
Tue Aug 30, 2022 9:48 am
Paul Buckley wrote:
Mon Aug 29, 2022 8:40 pm
Lovely colour!

Stateside car? I thought that no S3 cars came with wires.
Is it a conversion?
Or am I wrong?
Thank you. Sable brown, cinnamon interior. on paper sounds awful but in the flesh strangely fitting to its lines. Thats the original paint, chrome (except for UK overiders), softtop, leather and carpets.
There seem to be quite a few with wire wheels.
Yes stateside car, according to original invoice wire wheels were a factory fit extra.
Just checked, the wire wheels were a $275 extra factory fit.
Regards
Paul C
1973 Series 3 OTS
1964 semi lightweight race car in build
1995 P38 Range Rover, owned from new, LPG
1983 JCB 3CX Sitemaster with sidehammer
1989 Bultaco Frontera Mk 15 370cc
1985 Bultaco Sherpa 199B 325cc

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cunpr
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#32 Re: Fuel gauge not registering properly

Post by cunpr » Mon Sep 12, 2022 6:28 pm

Dear All,
A shout out for JDO instruments who repaired my broken Kienzle clock, excellent rapid service.
One thought, i understand the clocks go out of time because they are electrically driven, JDO calibrated mine for 13.2 volts but that voltage will vary as the cars sits and discharges and then re-charges as it runs. So what about supplying it from a voltage regulator, set at say 12 volts? Should be possible to do the calibration and then the constant voltage will avoid it loosing time? I doubt it can be calibrated down to run of the original 10v regulator but an aftermarket one set for 12V should fix the issue?
Regards
Paul C
1973 Series 3 OTS
1964 semi lightweight race car in build
1995 P38 Range Rover, owned from new, LPG
1983 JCB 3CX Sitemaster with sidehammer
1989 Bultaco Frontera Mk 15 370cc
1985 Bultaco Sherpa 199B 325cc

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MontanaDiver
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Location: Great Falls, MT
United States of America

#33 Re: Fuel gauge not registering properly

Post by MontanaDiver » Tue Sep 27, 2022 5:27 am

My sender failed this past Fall. I ordered a new one from SNG and it read over full, and at 60 miles it went to full. I ran out of gas with 3/8 indicating. I bent the arm for the float several times until I was able to get the indicator to read correctly. Okay, 5 damn times! I reset the trip odometer and start looking for fuel at 150 miles in town and 200 miles on highway.
Dennis
74 E-type OTS 4 speed
Great Falls, Montana

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