Frankrhona
6th March 2017, 03:54 PM
Something was wrong! The fuel gauge was reading 1/4 and then it read 1/2 and then.... cough.....engine stopped. It is 40 in the shade in Sydney suburbia 60km from home. Hand primmed it a few time and no fuel! So I sat there while the subtank pumped over, then primmed it again and kept pumping whilst swmbo cranked the engine. Finally she fired up and away carried on to fill it up. This started my investigation. The vehicle is a 2005 GUIV ZD30 Patrol.
Read many posts on the forum which suggested the sender. Bought a new O-ring for the sender and proceeded to remove it and test it. Well it has been in and out 4 times now and I believe it is OK.
This is what I discovered. The tank at the sender is 300mm deep. The sender has a range of 210mm from 30mm off the bottom to 240mm, 60mm below the top. The sender has two parts, a float connected to a variable resistor and a full level magnetic float switch. The float switch is to to stop the sub tank from over filling the main tank. The variable resistor measures the depth: Empty 81 ohms, 1/4:51 ohms, 1/2:30 ohms, 3/4 14 ohms and Full 5 ohms. It is not linear, but follows a reasonably flat curve and for general purposes could be considered linear. (Have you noticed, once your gauge starts moving, it gets to 1/2 faster than 1/2 to empty? Non-linear!
The sender is connected to the Unified Meter Control via a wiring harness running up the passenger side. I still have the problem of the fuel gauge going down to 1/2 or 1/4 then starting to climb back to show about 1/4 tank too much. Frustrating. I have connected a flying lead to the sender wire at plug C123 located behind the passenger side kick panel and an earth wire to test the sender. To date I can not fault the sender, and use a multimeter to check the real fuel level. The fault indicates the Unified Meter Control is faulty or the input resistance is dropping by about 20 ohms.
Can anyone advise me how hard it is to remove and replace the Unified Meter Control? I'm guessing it is located on the back of the gauges. If anyone can shed some more light on my problem, it will be greatly appreciated.
Cheers,
Andrew
Read many posts on the forum which suggested the sender. Bought a new O-ring for the sender and proceeded to remove it and test it. Well it has been in and out 4 times now and I believe it is OK.
This is what I discovered. The tank at the sender is 300mm deep. The sender has a range of 210mm from 30mm off the bottom to 240mm, 60mm below the top. The sender has two parts, a float connected to a variable resistor and a full level magnetic float switch. The float switch is to to stop the sub tank from over filling the main tank. The variable resistor measures the depth: Empty 81 ohms, 1/4:51 ohms, 1/2:30 ohms, 3/4 14 ohms and Full 5 ohms. It is not linear, but follows a reasonably flat curve and for general purposes could be considered linear. (Have you noticed, once your gauge starts moving, it gets to 1/2 faster than 1/2 to empty? Non-linear!
The sender is connected to the Unified Meter Control via a wiring harness running up the passenger side. I still have the problem of the fuel gauge going down to 1/2 or 1/4 then starting to climb back to show about 1/4 tank too much. Frustrating. I have connected a flying lead to the sender wire at plug C123 located behind the passenger side kick panel and an earth wire to test the sender. To date I can not fault the sender, and use a multimeter to check the real fuel level. The fault indicates the Unified Meter Control is faulty or the input resistance is dropping by about 20 ohms.
Can anyone advise me how hard it is to remove and replace the Unified Meter Control? I'm guessing it is located on the back of the gauges. If anyone can shed some more light on my problem, it will be greatly appreciated.
Cheers,
Andrew