Sending unit difference 84 and 89? fuel gauge wont read now
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Joined: Dec 2005
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From: St. Cloud, MN
Car: 1984 Trans Am
Engine: LS1383 in work
Transmission: Magnum F - to be installed
Axle/Gears: Zexel Torsen 3.73, 28-spline mosers
Sending unit difference 84 and 89? fuel gauge wont read now
Hey guys,
I am installing a new sending unit from an 89 into my 84 T/A. The connectors are keyed the same but now my gauge is pegged at way passed full. Any thoughts on why this is? Is the sending unit from the 89 using different value than my 84 gauge wants to see?
I am installing a new sending unit from an 89 into my 84 T/A. The connectors are keyed the same but now my gauge is pegged at way passed full. Any thoughts on why this is? Is the sending unit from the 89 using different value than my 84 gauge wants to see?
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
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Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Sending Information
Yes there is a difference.
The potentiometer has a different Ω value.
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Happy Racing!
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How bout those too scared to drive without headlights in the daytime
and the ones that need headlights for a little rain
.
The potentiometer has a different Ω value.
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Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
How bout those too scared to drive without headlights in the daytime
and the ones that need headlights for a little rain.
Thread Starter
Joined: Dec 2005
Posts: 4,795
Likes: 15
From: St. Cloud, MN
Car: 1984 Trans Am
Engine: LS1383 in work
Transmission: Magnum F - to be installed
Axle/Gears: Zexel Torsen 3.73, 28-spline mosers
Re: Sending Information
So how do I fix this? Put in a fuel gauge from an 89? what year was the change?
Would a gauge from an 85 work? I have one of those in the garage.
Joined: Mar 2000
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From: Orange, CA
Car: '90 Trans Am-12.45@110.71
Engine: 355 w/AFR 195's Elem. 400/430 HP/TQ
Transmission: Tremec T-56
Axle/Gears: 12 Bolt 3.73
Re: Sending Information
If the ground isn't making good contact it will go all the way to full.
Thread Starter
Joined: Dec 2005
Posts: 4,795
Likes: 15
From: St. Cloud, MN
Car: 1984 Trans Am
Engine: LS1383 in work
Transmission: Magnum F - to be installed
Axle/Gears: Zexel Torsen 3.73, 28-spline mosers
Re: Sending Information
I will double check all my connections tonight but the only one that changed was the factory orange wire...had to cut that to get splice in a 12v power source to run the pump. The others are untouched and the gauge worked fine before the swap.
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From: belle fourche,s.d.
Car: '82 z28
Engine: L83 5.7
Transmission: 700r4-1985
Axle/Gears: 3.42 posi
Re: Sending unit difference 84 and 89? fuel gauge wont read now
Two companies made the gauge clusters for 3rd gen
firebirds;delco for '82-85(and the base clusters for a few
yrs after '85) and nippondenso for most '86 up
probably different senders between the two...
firebirds;delco for '82-85(and the base clusters for a few
yrs after '85) and nippondenso for most '86 up
probably different senders between the two...
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From: Not in Kansas anymore
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Trending Topics
Thread Starter
Joined: Dec 2005
Posts: 4,795
Likes: 15
From: St. Cloud, MN
Car: 1984 Trans Am
Engine: LS1383 in work
Transmission: Magnum F - to be installed
Axle/Gears: Zexel Torsen 3.73, 28-spline mosers
Re: Sending Information
I will check my wires and if I set my multimeter to ohms, I on which lead will I measure the resistance? The pink power or the other ground wire? (Third wire being power for the pump)
Supreme Member
Joined: Jan 2006
Posts: 3,341
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Sending Information
1985 was the year they changed to the 90 Ω units
For a 1984 you can use a SunPro P/N CP7583.
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Happy Racing!
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How bout those too scared to drive without headlights in the daytime and the ones that need headlights for a little rain
.
For a 1984 you can use a SunPro P/N CP7583.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
How bout those too scared to drive without headlights in the daytime
and the ones that need headlights for a little rain.
Thread Starter
Joined: Dec 2005
Posts: 4,795
Likes: 15
From: St. Cloud, MN
Car: 1984 Trans Am
Engine: LS1383 in work
Transmission: Magnum F - to be installed
Axle/Gears: Zexel Torsen 3.73, 28-spline mosers
Re: Sending Information
So my 84 gauge won't work at all with my 89 sender? The sender is already installed along with the new tank. I have an 85 gauge cluster that I can install and try when I get home from my deployment at the end of January. Would that be the easiest ''correct'' fix for this?
Supreme Member
Joined: Jan 2006
Posts: 3,341
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Sending Information
That would make a lot of sense, you have the dash, I would do that.
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Happy Racing!
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If People Drove Any Slower They’d Be Going Backwards
.
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Happy Racing!
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If People Drove Any Slower They’d Be Going Backwards.
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Re: Sending Information
Thread Starter
Joined: Dec 2005
Posts: 4,795
Likes: 15
From: St. Cloud, MN
Car: 1984 Trans Am
Engine: LS1383 in work
Transmission: Magnum F - to be installed
Axle/Gears: Zexel Torsen 3.73, 28-spline mosers
Re: Sending Information
I just wonder what, if any other sender/gauge related problems may arise. I'm not all sure what changed between 84 and 85. Temp should be the same. Speedo is mechanical. Only oil pressure may be different. I know they changed sender styles one year for the oil pressure. I just don't like the grid pattern in the 85 gauges. the 84 has a plain black background. Oh well.
Re: Sending unit difference 84 and 89? fuel gauge wont read now
Before you worry about swapping out the gauge check the sender resistance and make sure it is right.
I used a 84 sender in my 88 and it worked fine...
I used a 84 sender in my 88 and it worked fine...
Thread Starter
Joined: Dec 2005
Posts: 4,795
Likes: 15
From: St. Cloud, MN
Car: 1984 Trans Am
Engine: LS1383 in work
Transmission: Magnum F - to be installed
Axle/Gears: Zexel Torsen 3.73, 28-spline mosers
Re: Sending unit difference 84 and 89? fuel gauge wont read now
Well, this is an 89 sender in my 84. Where should I measure the resistance at? Coming off of the harness from the sender? I guess it won't be at the two powered wires right?
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Joined: Jan 2006
Posts: 3,341
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Engaging Discussion
It’s a good idea to test the gage, and faster than replacing the dash or sender.
Here’s how to test the fuel gage.
Remove the sender wire going to the gage.
Tape the bare end of the sender wire and put it aside.
Use a potentiometer with a value of 240Ω or the closest you can find.
You should mount the potentiometer on a panel and install a ****, then using an ohmmeter plot the resistance on the panel.
Connect one end the potentiometer to the gage from the location you removed the sender.
Connect the wiper of the potentiometer to ground.
Turn the key to RUN.
Slowly adjust the potentiometer.
If you have a 240Ω compatible gage it will indicate ½ tank @ 120Ω, full @ 30Ω, empty @ 240Ω.
If you have a 90Ω compatible gage it will indicate ½ tank @ 45Ω, full @ 90Ω, empty @ 0Ω.
If the gage is bad it will exhibit the problem you have.
If the gage is good it will display a smooth transition from one end of it’s range to the other.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
If People Drove Any Slower They’d Be Going Backwards
.
Here’s how to test the fuel gage.
Remove the sender wire going to the gage.
Tape the bare end of the sender wire and put it aside.
Use a potentiometer with a value of 240Ω or the closest you can find.
You should mount the potentiometer on a panel and install a ****, then using an ohmmeter plot the resistance on the panel.
Connect one end the potentiometer to the gage from the location you removed the sender.
Connect the wiper of the potentiometer to ground.
Turn the key to RUN.
Slowly adjust the potentiometer.
If you have a 240Ω compatible gage it will indicate ½ tank @ 120Ω, full @ 30Ω, empty @ 240Ω.
If you have a 90Ω compatible gage it will indicate ½ tank @ 45Ω, full @ 90Ω, empty @ 0Ω.
If the gage is bad it will exhibit the problem you have.
If the gage is good it will display a smooth transition from one end of it’s range to the other.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
If People Drove Any Slower They’d Be Going Backwards.
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Re: Sending unit difference 84 and 89? fuel gauge wont read now
Nina--
As always, your tips // advice make me wonder if you were on the electronics division of GM for the 3rd gens!! LOL!!!!
Back to topic of gauges compatibility---
From 85 or 86 - 92, the gauge clusters are swappable??
Our problem---
Harness, gauges, & full dash // console
are from a Firebird of unknown year, motor is a 92 350 no ECM. Gas gauge doesn't work properly, no water temp, oil pressure, or speedo. I can see a VSS yellow thing on the back side of the speedo.
This is in our 87 Camaro.
So, not having the ohm meter, is the above test able to be done at a competent auto shop??
If all else falls into place, then we are going to get the digital gauge system talked about in another thread.
Thanks for you Q Ozz1967
As always, your tips // advice make me wonder if you were on the electronics division of GM for the 3rd gens!! LOL!!!!
Back to topic of gauges compatibility---
From 85 or 86 - 92, the gauge clusters are swappable??
Our problem---
Harness, gauges, & full dash // console
are from a Firebird of unknown year, motor is a 92 350 no ECM. Gas gauge doesn't work properly, no water temp, oil pressure, or speedo. I can see a VSS yellow thing on the back side of the speedo.
This is in our 87 Camaro.
So, not having the ohm meter, is the above test able to be done at a competent auto shop??
If all else falls into place, then we are going to get the digital gauge system talked about in another thread.
Thanks for you Q Ozz1967
Thread Starter
Joined: Dec 2005
Posts: 4,795
Likes: 15
From: St. Cloud, MN
Car: 1984 Trans Am
Engine: LS1383 in work
Transmission: Magnum F - to be installed
Axle/Gears: Zexel Torsen 3.73, 28-spline mosers
Re: Sending unit difference 84 and 89? fuel gauge wont read now
So, the long and short of it is...
KISS....Keep it Simple Stupid.
Just got home from my Caribbean cruise and went out to re-engage with my fuel sending unit issues. First stop, the three-wire connector near the back of the fuel tank that came with the sender. All looks good. Double checked the other side coming from the car. There is part of it. Had two wires crossed when I fixed a previous owner repair while the tank was out. Discovered this by looking at the old connector I cut from the old sender but saved. Smart move that. Got me looking at the plugs. Yes, they were female. Looked at the plugs on the new sender...male. SO, I'm trying to plug a male to a male. oops. Isn't always making contact with the plug. So, I just need to clean the garage enough to pull the car in and splice in the old harness plug with the female connectors. I just abhorr working in the snow! The short of it is, the gauge is working now. YAY
KISS....Keep it Simple Stupid.
Just got home from my Caribbean cruise and went out to re-engage with my fuel sending unit issues. First stop, the three-wire connector near the back of the fuel tank that came with the sender. All looks good. Double checked the other side coming from the car. There is part of it. Had two wires crossed when I fixed a previous owner repair while the tank was out. Discovered this by looking at the old connector I cut from the old sender but saved. Smart move that. Got me looking at the plugs. Yes, they were female. Looked at the plugs on the new sender...male. SO, I'm trying to plug a male to a male. oops. Isn't always making contact with the plug. So, I just need to clean the garage enough to pull the car in and splice in the old harness plug with the female connectors. I just abhorr working in the snow! The short of it is, the gauge is working now. YAY
Last edited by Ozz1967; Jan 21, 2011 at 07:57 PM.
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