Lotus Elan

Fuel Gauge Sender Unit

PostPost by: Fourducs » Sun Nov 21, 2021 3:45 pm

Maybe this question should be posted under the Fuel System. I dunno.

I just received a new aluminum fuel tank from SJ Sports Cars. The tank came with a fuel gauge sender unit installed. The unit in the new tank has two posts for electrical connections. The sender unit in my car has three posts and electrical connections. Can anyone offer insight other than recontacting SJ Sports Cars and inquiring about 3 post sender units. BTW, I was very pleased with SJ Sports Cars' timely filling of this order.

My car is a 1969 Elan +2, LHD, non federal, #2305.
Fourducs
New-tral
 
Posts: 12
Joined: 29 Sep 2021
Location: Charlotte, NC, USA

PostPost by: HCA » Sun Nov 21, 2021 6:20 pm

The third terminal is for a warning light.

You will have to contact SJ to replace it with the correct unit, or do without the warning light and just relie on the gauge.
Hal Adams

Evora - the poser
Elan +2 - keeps me busy
Macan - hers
Felicia Pickup - my favourite
HCA
Fourth Gear
Fourth Gear
 
Posts: 630
Joined: 03 Jan 2020
Location: Limoux, France

PostPost by: Fourducs » Sun Nov 21, 2021 6:29 pm

Thanks HCA. That makes sense.
Fourducs
New-tral
 
Posts: 12
Joined: 29 Sep 2021
Location: Charlotte, NC, USA

PostPost by: Lotusian » Mon Nov 22, 2021 7:26 am

SJ’s website shows the sender with two insulated terminals (1 for gauge and 1 for warning light) plus one uninsulated earth tag (ground).
Perhaps the earth tag has broken off or got squashed?

https://www.sjsportscars.com/files/X050 ... jpg?mod=86
Lotusian
Second Gear
Second Gear
 
Posts: 85
Joined: 27 Nov 2016
Location: Essex UK

PostPost by: Bigbaldybloke » Tue Nov 23, 2021 1:18 am

Fairly simple to test if you have a multimeter, check between the terminals and the switch body, the low fuel indication is a switch, with no fuel the contact should be made and should be effectively a short circuit and the gauge is a variable resistor which will change gradually as the float moves up and down. Both circuits go to earth so if the tank is still out of the car, just measure each terminal to the tank and rotate the tank to move the float around in the tank and see what changes. If the tank is in the car it probably easiest to just take the sender out and test it on the bench, probably need a new gasket though. It there is only a level sender fitted and no switch you won’t get a reading from the terminals to the tank, you’ll only get a variable resistance reading between the two terminals.
Mind you a phone call to the vendor might be simpler and quicker!
Change is inevitable, except from a vending machine!
Bigbaldybloke
Fourth Gear
Fourth Gear
 
Posts: 871
Joined: 16 May 2017
Location: Lincolnshire

PostPost by: Fourducs » Tue Nov 23, 2021 2:06 am

I am missing the earth tab on my new sender unit. I see no sign of it. I may fashion one up and check the two insulated terminals to see if one lights up the low fuel light. The other one should change the indicated fuel level when I move the tank around as suggested by Bigbaldybloke. Thanks for the input guys.
Fourducs
New-tral
 
Posts: 12
Joined: 29 Sep 2021
Location: Charlotte, NC, USA

PostPost by: Fourducs » Thu Nov 25, 2021 5:19 pm

I did talk to the vendor, SJ Sportscars. For the curious here is the answer:
The sending unit supplied with SJS's aluminum replacement tanks only has two electrical connections. One for earth and one for the fuel gauge. There is no switch for the low fuel light included in the sending unit that comes with the new tank. One cannot switch the old sending unit over, or install the replacement sending unit that SJS sells because they mount differently to the tank. The sending unit with the new tank is attached by 6 screws instead of a locking ring. I can drive without the low fuel light, although I would prefer to have everything working.

Other than that the tank appears to be good quality, the same size & shape, and fits in nicely. The threads for the drain plug and fuel line are correct. It does lack the two depressions on the bottom of the original tank that were designed to provide clearance for two bolts that protrude through the body under the fuel tank. I don't think that is going to be a problem.
Fourducs
New-tral
 
Posts: 12
Joined: 29 Sep 2021
Location: Charlotte, NC, USA

Total Online:

Users browsing this forum: No registered users and 8 guests