Matching fuel guage to sender

[kdn17]

I did a search and found various solutions but wondered if anyone has come up with an alternative solution in the 2 years since the last posting. There are probably enough new members to warrant raising the question again - waiting for the engine to splutter on tight left handers as an indication of low fuel is not really very good practise

[dogoncrazy]

Re: Matching fuel guage to sender

There are certainly a number of interesting solutions, the electronics of which are certainly beyond me! Maybe I was just lucky when I used a Smiths gauge ,universal sender and a voltage stabiliser and ended up with an accurate gauge.

[b_caswell]

Re: Matching fuel guage to sender

As we havnt got the old posting, give us a clue what gauge and what tank on what car?

[kdn17]

Re: Matching fuel guage to sender

Hi Ben, it was a bit of a generic question but for my car Ford Sierra 2.0 DOHC fuel injection model and SW gauges (no longer available I think). Sender on donor gives 20 - 24 ohm across Ford gauge for full and 143- 150 ohm for empty. I can't get to the back of the gauge that easily so went to the top of the sender.
3 sender terminals (with my SW gauge fitted).
A - B : 191 empty ; 281 full
B - C : 2.2 empty ; 0.5 full
C - A : 2.1 empty ; 1.4 full

(Ben - if you enter "fuel gauge" into the search engine on the forum you should get the postings Alan & I referred to).

My knowledge of electronics is pretty much zilch. A guy from the Dunstable area very kindly gave me a circuit quite some time ago but I could not get it going and after several months eventually got to the point that I was too embarrassed to admit my failure.

The reason for my raising the problem again is to see if there are any new solutions that make use of new components to provide an easily adjustable "one fits all" fix. Come on you electronics whizzes.

[b_caswell]

Re: Matching fuel guage to sender

Hi Keith, Still didnt find old entry but no matter.On the roadster with an escort tank and Smiths/Jaeger gauges the gauge reads about quarter full when its actually empty, by fitting a 16ohm resistor inline of the feed to the gauge it then reads about right. As being empty is the most important info I would try either a variable or a selection of resisters until you get a correct empty reading. I think one of the terminals on your sender is for the low fuel light, I will try asking a Ford/Caterham friend but let me know what tank and sender your using.

[b_caswell]

Re: Matching fuel guage to sender

That should read resistor on feed from gauge to send

[kdn17]

Re: Matching fuel guage to sender

Hi Ben, Thanks for that. The tank is a purpose made YKC one (no swirl pot or baffles unfortunately). The sender is an integrated immersed pump, sender etc from a Sierra GLS

[milliemarlin]

Re: Matching fuel guage to sender

I have a related question.

I am trying to understand the Mondeo’s fuel gauge.

It looks from the wiring diagram of the Mondeo Speedo as if the fuel tank unit contains a simple variable resistance. This is connected to an electronic black box in the instrument cluster. This seems to drive both the fuel gauge and the low fuel indicator lamp.

Does anybody know if this black box could be used in combination with a Sierra sender to create a stabilised fuel gauge with the all-important warning light?

I will attempt to attach a picture of the wiring diagram.

Paul

PS: The original append was in the Roadster forum. Search for: Fuel Gauge within: All Categories from the main forum page.

[kdn17]

Re: Matching fuel guage to sender

Hi Paul,

You could try writing to the Ford Technical Information Centre, PO Box 300, Walsall, WS5 4QH. They have been very helpful in the past - I don't know what their policy is now. If the answer to your question is yes then you have prretty much solved my problem as well. If you do write, could you add in an extra question please and that is, if the answer to your question is yes, can the black box be installed near the sender rather than at the instrument cluster.
Best of luck

[robert]

Re: Matching fuel guage to sender

My design had a warning light too :-)

[danny_nelson]

Re: Matching fuel guage to sender

Marlins solution. External secondary small tank . External pump, pumping to small tank. SW instrument with SW sender ( still available from Merlin Motorsport)

[milliemarlin]

Re: Matching fuel guage to sender

I have written a bit about this for the next magazine, providing Sue has space for it.

The long and the short of it is that the Mondeo’s gauge and electronics work well with a 10 to 180 ohm sender. Even the fuel light works. The bad news is all the electronics are part of the Speedo so it would be difficult to separate them.

I would like to experiment with the wiring diagram Posted by Rob Money on 9th Jun 05. Perhaps including it in a future article. Rob if you see this please can you let me know if you are happy with that.

Finally I can’t source some components. Do you know if these, available from Maplin would be ok?

1N5357 20V 5W = BZV85C 20V 1.3W

LMC660 = LM324N 324

BST72 = 2N7002 : VDS(V) 60 ID(A) 0.3 0. PTOT(W) 83
Or = IRF540 : VDS(V) 100 ID(A) 30 PTOT(W) 100

Do you know what the sender resistance is? (10 to 180 would be the best answer).

Thanks in advance, Paul

[keith_h]

Re: Matching fuel guage to sender

Hi Paul,

Having started this thread and a) not being into electronics and b) not really getting any nearer to a solution I asked a Physics Doctorate to take a look and he concluded that with a 30Om 5watt pot in the circuit (which he drew out for me) I could work out what fixed resistance would be needed to match up my system. Theory is a fine thing. The first problem is to find such a pot at a realistic price. The other interesting point is that this is roughly in the realm of the 16Ohm resistance that Ben suggested earlier. If anyone has such a pot that I can borrow or an point me to a reasonably priced one I would really appreciate it.

[macdonald.dm]

Re: Matching fuel guage to sender

Hi Keith H.

Are you trying to get the sender of your current tank to match that of the donor Sierra's? Ie: are you trying to get the sender to 'behave' as if it has the following values (taken from your post above): 20-24 at Full, and 143-150 Empty?

[keith_h]

Re: Matching fuel guage to sender

Hi Donnie,

No, I have used the immersed pump and sender from the Sierra. I am told my SW guage is 33 Ohm full and 240 Ohm empty and as it is essentially an ammeter, I suppose, all that is needed is an appropriate resistor to match things up, as per Ben. I have an inkling however, that my setup will need a different value.