4A-GZE MK1 Engine Tiny Light, tiny problem?

mr2tim · 05-01-2008, 09:53 PM

Not being very electrically inclined,
I'd like to ask if any of our mr2 owners have ever had a sticky gas gauge light and succeeded with a remedy? (Please don't make me pull this tank again

)

Flushed the new tank, popped in the pump. Reinstalled.

Yep, connections tested ok.

Wires outside the tank all show continuity.

Any electricians out thar?

Thanks now for your help later,

mr2tim

1fastmr2 · 05-10-2008, 09:48 AM

Please give more detail of sticky?

mr2tim · 05-20-2008, 02:02 PM

The lights on constantly w filled tank.

Ben · 05-20-2008, 03:22 PM

So the fuel gauge will read full, but the light will be on? Or will the fuel gauge be on empty with a full tank?

1fastmr2 · 05-20-2008, 06:11 PM

The tank is full of fuel and the light is on. I have seen this before. The sensor in the tank has failed.

bassman54 · 10-23-2010, 11:26 AM

Mine has a different problem but the cause is the same. My light never comes on.

The "sensor" is a special resistor that changes value when it's in air versus covered by fuel. I had the same problem with my '82 Supra.

Now for the question: who out there KNOWS the value and whether it is PTC or NTC ?

This is a question for someone who knows car electronics. PTC and NTC are whether the resistance goes up or down with temperature increase. It's worth it to me to fix this.

toyotaspeed90 · 10-23-2010, 08:43 PM

the pickup sensor in the tank is actually accessible without removing the tank...

remove the center console armrest and, IIRC, this is just in front of or behind (can't remember...) the 5 speed shifter.... has 3? screws holding it on.... maybe if you pulled the tank you didn't reconnect the sensor? It's NOT built into the pump assembly...

m_r_2 · 10-23-2010, 09:03 PM

i think i need to replace mine i know i have let the fuel get real low and never has the light came on, now i know why.

Pofje · 10-31-2010, 11:34 AM

I got a book I can pull out to tell you how to tell the resistors from each other..... I will do this later tonight as it's time for work.

Pofje · 10-31-2010, 08:43 PM

A PTC will increase in resistence when temp is increased. A NTC will decrease as temp increases. the resistence can be enough to complete or break a circuit at any given temp. From the looks of the wiring diagram it's a resistor that decreases in resistence as fuel drops I could be wrong. I would need pic of said resistor...... Sorry this is HVAC schooling kicking in. They do mess up from time to time from what I saw.

However if it's just a switch that closes when fuel is too low it just probly got stuck in the closed setting. Thats my two cents sorry if it didn't help X.X

05-01-2008, 09:53 PM	#1 (permalink)
mr2tim SUPERcharZed ToyZ RacZer Join Date: Mar 2008 Location: South Florida Posts: 1,789 Thanks: 8 Thanked 118 Times in 111 Posts My Google Map iTrader Rating: (6/100% )	Tiny Light, tiny problem? Not being very electrically inclined, I'd like to ask if any of our mr2 owners have ever had a sticky gas gauge light and succeeded with a remedy? (Please don't make me pull this tank again) Flushed the new tank, popped in the pump. Reinstalled. Yep, connections tested ok. Wires outside the tank all show continuity. Any electricians out thar? Thanks now for your help later, mr2tim

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05-10-2008, 09:48 AM	#2 (permalink)
1fastmr2 SPIN Join Date: Apr 2008 Location: Burlington, N.C. Posts: 108 Thanks: 2 Thanked 2 Times in 2 Posts iTrader Rating: (0/0% )	Please give more detail of sticky?

05-20-2008, 02:02 PM	#3 (permalink)
mr2tim SUPERcharZed ToyZ RacZer Join Date: Mar 2008 Location: South Florida Posts: 1,789 Thanks: 8 Thanked 118 Times in 111 Posts My Google Map iTrader Rating: (6/100% )	The lights on constantly w filled tank.

05-20-2008, 03:22 PM	#4 (permalink)
Ben Same In The End Join Date: Aug 2006 Location: Oceanside, CA / Reno, NV Posts: 4,274 Thanks: 20 Thanked 309 Times in 284 Posts My Google Map iTrader Rating: (16/100% )	So the fuel gauge will read full, but the light will be on? Or will the fuel gauge be on empty with a full tank?

05-20-2008, 06:11 PM	#5 (permalink)
1fastmr2 SPIN Join Date: Apr 2008 Location: Burlington, N.C. Posts: 108 Thanks: 2 Thanked 2 Times in 2 Posts iTrader Rating: (0/0% )	The tank is full of fuel and the light is on. I have seen this before. The sensor in the tank has failed.

10-23-2010, 11:26 AM	#6 (permalink)
bassman54 Ol' School Skills Join Date: Dec 2008 Location: So Cal Posts: 184 Thanks: 15 Thanked 16 Times in 15 Posts iTrader Rating: (1/100% )	Mine has a different problem but the cause is the same. My light never comes on. The "sensor" is a special resistor that changes value when it's in air versus covered by fuel. I had the same problem with my '82 Supra. Now for the question: who out there KNOWS the value and whether it is PTC or NTC ? This is a question for someone who knows car electronics. PTC and NTC are whether the resistance goes up or down with temperature increase. It's worth it to me to fix this.

10-23-2010, 08:43 PM	#7 (permalink)
toyotaspeed90 No Skills Join Date: Jun 2006 Location: Bellingham, WA Posts: 2,401 Thanks: 0 Thanked 148 Times in 143 Posts My Google Map iTrader Rating: (0/0% )	the pickup sensor in the tank is actually accessible without removing the tank... remove the center console armrest and, IIRC, this is just in front of or behind (can't remember...) the 5 speed shifter.... has 3? screws holding it on.... maybe if you pulled the tank you didn't reconnect the sensor? It's NOT built into the pump assembly...

10-23-2010, 09:03 PM	#8 (permalink)
m_r_2 I_ask2learn Join Date: Oct 2010 Location: PA Posts: 262 Thanks: 20 Thanked 6 Times in 6 Posts iTrader Rating: (0/0% )	i think i need to replace mine i know i have let the fuel get real low and never has the light came on, now i know why.

10-31-2010, 11:34 AM	#9 (permalink)
Pofje Cage Fighter Join Date: Mar 2010 Posts: 153 Thanks: 1 Thanked 1 Time in 1 Post iTrader Rating: (0/0% )	I got a book I can pull out to tell you how to tell the resistors from each other..... I will do this later tonight as it's time for work.

10-31-2010, 08:43 PM	#10 (permalink)
Pofje Cage Fighter Join Date: Mar 2010 Posts: 153 Thanks: 1 Thanked 1 Time in 1 Post iTrader Rating: (0/0% )	A PTC will increase in resistence when temp is increased. A NTC will decrease as temp increases. the resistence can be enough to complete or break a circuit at any given temp. From the looks of the wiring diagram it's a resistor that decreases in resistence as fuel drops I could be wrong. I would need pic of said resistor...... Sorry this is HVAC schooling kicking in. They do mess up from time to time from what I saw. However if it's just a switch that closes when fuel is too low it just probly got stuck in the closed setting. Thats my two cents sorry if it didn't help X.X