• Hi Guest! Being a Paying Supporter is NOT a requirement to participate at BCF. However, subscribing will help ensure we can continue to serve the LBC community for years to come. If you enjoy BCF and find our forum a useful resource...Please consider supporting us by **Upgrading**
    (PS: Subscribers don't see this banner)
Tips
Tips

TR2/3/3A Fuel sender or gauge?

Hermund

Freshman Member
Offline
Hi there.
Problem: My fuel gauge never shows more 1/4 full, even when "filled up".
But when the tank is really less then 1/4, the gauge starts working and shows almost accurate on it way to empty.

Now I've tested the gauge (Jaeger FG2530/20) by disconnecting connector T, and it passed the test described i "service manual".
Today I looked at the sender(FT3331/02), measuring ohm. the tank is well over 1/2, and I have a reading of 57 ohm. When pushing the float a little down, the reading changes accordingly, 45-50 ohms. My conclusion is that it works. Also disconnected the connector to the gauge(on the sender), and the gauge shows "full".
Connection ok, as far as I understand.

I've put on a new earth cable on the gauge, and checked the earth on the sender also. Seems ok.

I was quite sure the fault was at the sender end, so the instrument panel is all assembled, and I hate to take it out again and find nothing..

Question: I started to think (that is always dangerous), but is it possible that the two connectors on the gauge are swapped? will that create something like this?

Looking forward to suggestions :smile:

Pardon my English, but a Norwegian living in France..
I say no more ;)
 

CJD

Yoda
Country flag
Offline
Have you made sure the float arm is not snagging the side of the tank? It sounds like maybe the float is not rising fully when full.
 

Gliderman8

Yoda
Gold
Country flag
Offline
I had a similar problem with my TR6. It turned out to be the plastic float was filled with fuel. A new brass replacement and it is working.
 

M_Pied_Lourd

Darth Vader
Country flag
Offline
Have you made sure the float arm is not snagging the side of the tank? It sounds like maybe the float is not rising fully when full.

+1
 

dklawson

Yoda
Offline
Give a read through the fuel gauge pages on the MGA site that Geo posted the link to above.

Good clean ground connections are required for the magnetic gauges to work properly. I know you have run the new grounds but make sure all the connections are clean and that the new ground wires are making good contact with the gauge and sender.

A leaky float as Elliot said is also quite possible. There is a Ford brass float (# COAZ=9202-B) that can be used in place of the Smiths one. You will find them on eBay and many online suppliers.

While it could be a bent float arm snagging on something in the tank, that is less likely if the gauge ever worked properly for you.
 
OP
H

Hermund

Freshman Member
Offline
Thanks for a quick response, guys!

I have never seen it work properly, neither has the previous owner.

The floatarm is floating freely, on the surface. When I push it down, the readout of my instrument changes as expected.

Earth is usually a problem, and for my sender unit, the connection to Earth(under the tank) doesn't look too good, somewhat rusty. But, on the other hand, measuring between sender earthconnector and earth on the dash, I get a clear, no hesitation, "beep" from the istrument, and it shows zero ohms. I will find more good-looking solution to that.

I've been on the MGA site before, but used the "shortcut". I'll do it the hard way now.

By the way, no one commented on my question. Will swapping turn the needle around?
 

dklawson

Yoda
Offline
By the way, no one commented on my question. Will swapping turn the needle around?

The "T" terminal on the gauge must receive the green/black wire from the (fuel Tank) sending unit and the "B" terminal must receive power from a switched source (... from the Battery). The gauge will not work right if those connections are reversed.
 

6TTR3A

Jedi Warrior
Country flag
Offline
Hermund,
Take your test one step further: You said when you pushed down on the float, the resistance decreased
(which is correct) Now make a hook of some sort and pull the float UP as far as you can. The resistance
should now increase to as much as 85-90 ohms. If it does, it's the sender. As others mentioned, either
the float is leaking or dragging on something. It is possible to incorrectly install the sender. If the screw
holes on the sender are offset either one to the right or one to the left, the float will drag (and stop) on
the side of the tank. I would suggest removing the sender completely, reconnecting the T wire and the
ground wire, then moving the float thru its arc by hand. If the gauge registers properly, you've isolated
the problem. If the float appears to be empty, it was dragging. If it has petrol in it, find the hole,
enlarge it, drain it and solder the hole closed. Sender_2.jpg
 
Similar threads
Thread starter Title Forum Replies Date
Lutz Kramer Fuel gauge and sender unit for BJ8 Austin Healey 2
J Fuel sender, fuel gauge 100 4 Austin Healey 6
T Fuel Gauge & Sender Unit Austin Healey 5
newmexTR3 fuel gauge/sender wiring Triumph 7
NutmegCT TR2/3/3A fuel gauge / sender TR3A Triumph 25
jhorton3 Fuel Gauge Sender Spridgets 4
L Fuel sender specs... inaccurate gauge?? Spridgets 4
FlyingCat Spitfire Fuel Sender Unit Triumph 2
JPSmit Fuel tank sender - how does it work? Spridgets 4
Healey Nut Fuel Sender Austin Healey 3
sim fuel tank sender reading full all the time Spridgets 9
R Fuel sender internal wire Austin Healey 13
L Fuel Tank sender 100/6 Austin Healey 8
S fuel sender Austin Healey 7
rjc157 Fuel tank sender Austin Healey 13
S Hot tip: seal for fuel tank sender Austin Healey 9
T TR2/3/3A fuel sender Triumph 12
J Orientation of sender in fuel tank Spridgets 2
I Fuel sender unit testing Triumph 2
Jeepster New fuel sender unit Austin Healey 9
J Busted Fuel Tank Sender Unit Screws Austin Healey 7
M Fuel sender unit float leaks Triumph 8
G MGB Fuel sender '71 MGB MG 9
martx-5 TR2/3/3A TR3 Fuel Sender From Moss Triumph 8
T TR6 Bolt size/thread count for fuel sender TR4/TR6 Triumph 16
pjsmetana Fuel Level Sender needed... Triumph 5
T How best to test a fuel sender off the car? Triumph 10
M Fuel Tank Sender? Triumph 2
Morris Fuel tank sender Spridgets 3
ncbugeye Can a Bugeye fuel tank sender be restored? Spridgets 7
Randy Harris Fuel sender gasket - replace w/full Tank? Austin Healey 8
healeynut Ebay Fuel Tank Sender Austin Healey 5
T TR6 Repair or replace TR6 fuel level sender unit Triumph 4
G TR6 Fuel sender resistance for TR6 Triumph 1
A Fuel tank sender - direction to install? Austin Healey 3
dklawson TR4/4A TR4-TR4A Fuel Sender Resistance? Triumph 3
B Fuel Tank Sender Austin Healey 7
TypeRboy Fuel guage sender for Elans Lotus 0
T SU Fuel Pump Mounting Austin Healey 5
G Twin HS4 Su's leaking fuel Spridgets 17
G General MG Leaking Fuel on twin HS4's 1500 MG Midget MG 5
Boink Early Mini Fuel Gauge - adjusting it British Motor Corp 0
RJS General TR Winter Blend Fuel Triumph 1
D TR2/3/3A More Fuel pump questions. Triumph 10
Donald1107 59 TR3A Fuel Pump Triumph 48
BobHaskell SU Fuel Pump Pressure Austin Healey 1
S Large capacity fuel tank Spridgets 1
D TR2/3/3A rearmost fuel line question Triumph 5
fpstude TR4/4A Fuel Pipes Connector Triumph 4
Cutrog1 Fuel Pump Ticking Austin Healey 13

Similar threads

Top