Fuel gauges
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Discussion

mt308

Original Poster:

438 posts

165 months

Saturday 19th December 2015
quotequote all
For those of you using the standard Ultima dashboard with standard Ultima fuel gauges...

According to my wiring diagram there are 2 different makes that can be used - VDO and CAI.

Looking at my gauge, now out the car, there is no branding at all. It just says "Made in UK".

My senders are VDO.

Some gauges can be calibrated but I cannot see an obvious way to calibrate mine. I believe the VDO gauge might be able to be calibrated (certainly they do one that can be) so maybe I have a CAI gauge.

At the moment my gauge is as useful as a chocolate teapot - it does show full when full, but at about 5 litres below full it drops to about 1/8 full! (same on both sides). When completely empty it is below the 0. So I don't really ever know how much fuel I have unless completely full.

I wonder if anyone has one that can be calibrated (standard Ultima gauge that is)?

Thanks
Mark

mt308

Original Poster:

438 posts

165 months

Saturday 19th December 2015
quotequote all
Anyone good with electronics?!

Would this fix my problem - advantage of being cheap, pretty simple and retaining the proper Ultima gauge.

https://sites.google.com/site/shannonpowerlab2/hom...

There can't be many electrical circuits simpler than a fuel sender/fuel gauge...

Graham-P

1,548 posts

268 months

Saturday 19th December 2015
quotequote all
You might want to take a look at this new out it's a pricey, also I believe that Car Builder Solutions do something similar.

ETA. Looks like there's a mk3 version out now at £43

Edited by Graham-P on Saturday 19th December 20:52

F.C.

3,899 posts

230 months

Sunday 20th December 2015
quotequote all
mt308 said:
For those of you using the standard Ultima dashboard with standard Ultima fuel gauges...

According to my wiring diagram there are 2 different makes that can be used - VDO and CAI.

Looking at my gauge, now out the car, there is no branding at all. It just says "Made in UK".

My senders are VDO.

Some gauges can be calibrated but I cannot see an obvious way to calibrate mine. I believe the VDO gauge might be able to be calibrated (certainly they do one that can be) so maybe I have a CAI gauge.

At the moment my gauge is as useful as a chocolate teapot - it does show full when full, but at about 5 litres below full it drops to about 1/8 full! (same on both sides). When completely empty it is below the 0. So I don't really ever know how much fuel I have unless completely full.

I wonder if anyone has one that can be calibrated (standard Ultima gauge that is)?

Thanks
Mark
This gizmo:

https://www.spiyda.com/magento/index.php/fuel-gaug...

will let you use almost any gauge with any sender, I have one (not sure if it is the same supplier) that I have calibrated on a bench that I intend to fit on the car when I have time.
on the bench it worked a treat.
The "problem" with the Ultima set up is that the resistance range is very narrow, this device will broaden that range.

mt308

Original Poster:

438 posts

165 months

Sunday 20th December 2015
quotequote all
F.C. said:
mt308 said:
For those of you using the standard Ultima dashboard with standard Ultima fuel gauges...

According to my wiring diagram there are 2 different makes that can be used - VDO and CAI.

Looking at my gauge, now out the car, there is no branding at all. It just says "Made in UK".

My senders are VDO.

Some gauges can be calibrated but I cannot see an obvious way to calibrate mine. I believe the VDO gauge might be able to be calibrated (certainly they do one that can be) so maybe I have a CAI gauge.

At the moment my gauge is as useful as a chocolate teapot - it does show full when full, but at about 5 litres below full it drops to about 1/8 full! (same on both sides). When completely empty it is below the 0. So I don't really ever know how much fuel I have unless completely full.

I wonder if anyone has one that can be calibrated (standard Ultima gauge that is)?

Thanks
Mark
This gizmo:

https://www.spiyda.com/magento/index.php/fuel-gaug...

will let you use almost any gauge with any sender, I have one (not sure if it is the same supplier) that I have calibrated on a bench that I intend to fit on the car when I have time.
on the bench it worked a treat.
The "problem" with the Ultima set up is that the resistance range is very narrow, this device will broaden that range.
Thanks I have just placed an order - for the Mk3 which was £4 more and just out. The youtube demo is pretty impressive and it should not only sort out my issues but also allow for fairly accurate compensation for the shape of the tanks being narrower at the top than bottom. More wiring to fiddle around with now!

Mark

F.C.

3,899 posts

230 months

Sunday 20th December 2015
quotequote all
mt308 said:
Thanks I have just placed an order - for the Mk3 which was £4 more and just out. The youtube demo is pretty impressive and it should not only sort out my issues but also allow for fairly accurate compensation for the shape of the tanks being narrower at the top than bottom. More wiring to fiddle around with now!

Mark
It is a nice small package and seems to work well.
I hope it (they) work well on the car(s) and have good service life.
I know since fitting my Spa gauge set-up I have been short stopping to fill as even with the "universal" calibration of the spa gauge I was still not getting anywhere near linear (tank shape excepted) gauge level to miles covered with a red light at <20 miles useful left in the tank, which is a bit near the mark for me.

mt308

Original Poster:

438 posts

165 months

Wednesday 23rd December 2015
quotequote all
Quick wiring question as now have my box of tricks!

Am I right that the green wire is the positive feed, and the yellow wire is the feed from the senders?

Not sure I'll be allowed to work on it tomorrow, but you never know...

Thanks
Mark

MarkWebb

983 posts

239 months

Wednesday 23rd December 2015
quotequote all
Here's one for you clever B**gers!
I have motec dash and have calibrated fuel gauges perfectly however: When on right hand tank. If I switch on aircon. The reading drops a lot. Then jumping up and down as the compressor switches on and off with cab temperature. No problem with left tank. This is obviously a wiring issue but I wonder if it is inherent in the loom or is peculiar to my car?
Have a good xmas everybody!

F.C.

3,899 posts

230 months

Thursday 24th December 2015
quotequote all
MarkWebb said:
Here's one for you clever B**gers!
I have motec dash and have calibrated fuel gauges perfectly however: When on right hand tank. If I switch on aircon. The reading drops a lot. Then jumping up and down as the compressor switches on and off with cab temperature. No problem with left tank. This is obviously a wiring issue but I wonder if it is inherent in the loom or is peculiar to my car?
Have a good xmas everybody!
you need to nail down your earth wires sender end.

Steve_D

13,801 posts

280 months

Thursday 24th December 2015
quotequote all
MT380 green is the live.

Mark. You could be suffering the ignition switch issue where it is trying to carry too much current. I think the gauges and the aircon are on the same fuse so when it switches you get a volt drop on the gauge. (older cars used to have a voltage regulator behind the dash because gauges are so sensitive to have the correct voltage).

Steve

MarkWebb

983 posts

239 months

Thursday 24th December 2015
quotequote all
F.C. would think it was something like that but it seems not. Aircon compressor grounds to engine and sender ground is good.
Steve. I am lucky enough to have a bank of relays instead of the dodgy ignition switch.
Doesn't do it on left hand tank so can't be anything to do with dash.
Have proved that it is the compressor switching on and off causing the issue.
The only thing that isn't common is the ground but it seems good.