Fuel sender is supposed to be 0-90ohms, right?
Thread Starter
Launching!
Joined: Dec 2001
Posts: 259
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From: Durham, NC
Fuel sender is supposed to be 0-90ohms, right? Is anyone else using an autometer GM fuel gauge with an FBody sending unit? My gauge is reading 1/2 full when bone dry. It goes way past F when full.
I had the purple fuel sender wire getting split between the PCM pin and the fuel gauge. Thought that might be screwing it up, so I disconnected the PCM - now the wire just goes to the gauge. Still same reading though.
I definitely got the GM gauge. Just double checked my packing slip from Jegs.
I had the purple fuel sender wire getting split between the PCM pin and the fuel gauge. Thought that might be screwing it up, so I disconnected the PCM - now the wire just goes to the gauge. Still same reading though.
I definitely got the GM gauge. Just double checked my packing slip from Jegs.
Re: Fuel sender is supposed to be 0-90ohms, right? I have the SAME problem!
Chances are you have a 99+ fuel level sending unit in tank and a gauge for the old 98- style.
I have a 97 dash cluster in my car right now with the fuel level gauge hooked directly up to the 99+ fuel level sending unit, and I run out of gas at the half way point on my gauge. The first few times I almost was stranded!!!
I am hoping an intricate series of resistors, electrical tape, and crimps will solve the problem.
Chances are you have a 99+ fuel level sending unit in tank and a gauge for the old 98- style.
I have a 97 dash cluster in my car right now with the fuel level gauge hooked directly up to the 99+ fuel level sending unit, and I run out of gas at the half way point on my gauge. The first few times I almost was stranded!!!
I am hoping an intricate series of resistors, electrical tape, and crimps will solve the problem.
Thread Starter
Launching!
Joined: Dec 2001
Posts: 259
Likes: 1
From: Durham, NC
Re: Fuel sender is supposed to be 0-90ohms, right? I have a 99 sending unit which the factory service manual says is 0-90ohms and an autometer aftermarket fuel gague that is supposed to work with GM 0-90ohm sender.
BUT, you may be on to something. The salvage yard told me that they sold me a 99 tank (with sending unit). But maybe they jooked me.
I'll have to look up the specs for the 98.
BUT, you may be on to something. The salvage yard told me that they sold me a 99 tank (with sending unit). But maybe they jooked me.
I'll have to look up the specs for the 98.
Re: Fuel sender is supposed to be 0-90ohms, right? I bet your gauge is just calibrated for the older GM level senders.
Maybe this weekend I'll take an ohm meter to both level senders and see how they differ.
Maybe this weekend I'll take an ohm meter to both level senders and see how they differ.
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Launching!
Joined: Dec 2001
Posts: 259
Likes: 1
From: Durham, NC
Re: Fuel sender is supposed to be 0-90ohms, right? Well crap. The FactoryServiceManual lies then. I sure coulda bought a gauge that worked in that range. Now I have to jury rig something. Damn.
I have some wheel bearing issues - cars been up on jacks again, waiting for parts for the past 2 weeks. Bearing blew out and scrogged the hub.
I have some wheel bearing issues - cars been up on jacks again, waiting for parts for the past 2 weeks. Bearing blew out and scrogged the hub.
Re: Fuel sender is supposed to be 0-90ohms, right? I was thinking of putting a 50ohm resistor inline.... but then your full point will be near the 2/3 mark in reality.
So you might just have a more accurate 0/3 to 2/3 gauge?
So you might just have a more accurate 0/3 to 2/3 gauge?
Re: Fuel sender is supposed to be 0-90ohms, right? I ohm checked my 97 fuel level sender and found it to be 5ohm to 105ohm.. approx..
So, to get an accurate signal... truley accurate you need to divide the ohms in half, then subtract 20.. hmm.. is that possible?
I know you can just throw a 50 ohm resistor inline and that will put your E semi-close.. and you can try different resistors to get it how you want, but your full mark is really going to mean you have about 2/3 fuel left.
So, to get an accurate signal... truley accurate you need to divide the ohms in half, then subtract 20.. hmm.. is that possible?
I know you can just throw a 50 ohm resistor inline and that will put your E semi-close.. and you can try different resistors to get it how you want, but your full mark is really going to mean you have about 2/3 fuel left.
Re: Fuel sender is supposed to be 0-90ohms, right? Just did some math...
If you wire a 166ohm resistor in parallell with the fuel level sender circuit, ...
When the fuel level sender shows 250ohms, you will see 100 (FULL)
When the fuel level sender shows 40 ohm, you will see 32 (1/3)
If you wire a 144ohm resistor in parallell with the fuel level sender circuit, ...
When the fuel level sender shows 240ohms, you will see 90 (FULL)
When the fuel level sender shows 40 ohm, you will see 31.30 (1/3)
So... where's that leave us?? *sigh*.. we'll never really see true E
If you wire a 166ohm resistor in parallell with the fuel level sender circuit, ...
When the fuel level sender shows 250ohms, you will see 100 (FULL)
When the fuel level sender shows 40 ohm, you will see 32 (1/3)
If you wire a 144ohm resistor in parallell with the fuel level sender circuit, ...
When the fuel level sender shows 240ohms, you will see 90 (FULL)
When the fuel level sender shows 40 ohm, you will see 31.30 (1/3)
So... where's that leave us?? *sigh*.. we'll never really see true E
Thread Starter
Launching!
Joined: Dec 2001
Posts: 259
Likes: 1
From: Durham, NC
Re: Fuel sender is supposed to be 0-90ohms, right? We need a 40ohm "encourager".
I'm still pissed that my manual steared me so wrong. And of course I threw out the box for my gauge. Arrgh....
I'm still pissed that my manual steared me so wrong. And of course I threw out the box for my gauge. Arrgh....
Re: Fuel sender is supposed to be 0-90ohms, right? Well.. I believe 98 LS1's have the 0-90 ohm sender beacuse they have the metal tanks... and 99+ get the different ones. So your manual may not be that wrong.
What I'm going to try this evening is fabbing my old fuel level sending unit to my 99+ assembly.. and then I'll have a true 0-90 ohm gauge. Perhaps you could look into that?
What I'm going to try this evening is fabbing my old fuel level sending unit to my 99+ assembly.. and then I'll have a true 0-90 ohm gauge. Perhaps you could look into that?
Re: Fuel sender is supposed to be 0-90ohms, right? Ok.. I just refitted my old 0-90 sender to the 99+ fuel assmebly.. took a little bit of work and stuff but now I have at least what I think is an accurate fuel gauge.. time will tell.
Thread Starter
Launching!
Joined: Dec 2001
Posts: 259
Likes: 1
From: Durham, NC
Re: Fuel sender is supposed to be 0-90ohms, right? I can get an Autometer fuel gauge that reads 240 ohm empty/ 33 ohm Full. So, that is really close, except in the wrong direction. Seems plausible to just reverse the wires though, eh? Put the sender signal to ground and the ground to the sender pole?
If that works, I'd still need a resistor to bump it down past E (or else risk thinking I have a little bit of gas when it's actually dry).
If that works, I'd still need a resistor to bump it down past E (or else risk thinking I have a little bit of gas when it's actually dry).
Re: Fuel sender is supposed to be 0-90ohms, right? I don't think you can reverse it... resistance is resistance. It's not like +/- voltage.
What you COULD do is this.. what I did.. Call up junk yards and get a ~95-98 fuel pump assembly and just take off the fuel level sender which is 0-90 and kind of rig it up for your tank. That's what I did for mine and it works very well.
What you COULD do is this.. what I did.. Call up junk yards and get a ~95-98 fuel pump assembly and just take off the fuel level sender which is 0-90 and kind of rig it up for your tank. That's what I did for mine and it works very well.
Thread Starter
Launching!
Joined: Dec 2001
Posts: 259
Likes: 1
From: Durham, NC
Re: Fuel sender is supposed to be 0-90ohms, right? Yeah, that does sound really stupid now that you mention it.
So, you swapped the winding part, or the whole level assembly? As I recall, it was sort of a big one piece dealio. Urgh. Sounds like glue may be involved, eh?
Local yards won't sell me the sending unit... gotta buy the whole freakin tank. Ironic that way back when I got the tank, they gave me a 98 (or 97?) metal tank. I made them go get me the "correct" 99 unit. I needed to match up the FPR with the 99 PCM though.
So, you swapped the winding part, or the whole level assembly? As I recall, it was sort of a big one piece dealio. Urgh. Sounds like glue may be involved, eh?
Local yards won't sell me the sending unit... gotta buy the whole freakin tank. Ironic that way back when I got the tank, they gave me a 98 (or 97?) metal tank. I made them go get me the "correct" 99 unit. I needed to match up the FPR with the 99 PCM though.
Re: Fuel sender is supposed to be 0-90ohms, right? I swapped the whole level sending unit.. Basically, 2 spliced wires to the floating end. Can't just swap the "winding" part, or the part where the metal contacts metal to change resistance, They are very different pieces.
No glue, just a dremel and 2 big tie straps. I cut a nice little housign for it in my 99 fuel pump assembly so it fit snug, then just added the straps so it wouldn't pop out. It was a bitch to squeeze the whole unit into the tank though.
Give www.tacreationsusa.com and see if they have your part.. If THEY don't have it you could try www.speedautomotive.com but use them as a last resort.
Or you could look up a part and perhaps order it from GM.
No glue, just a dremel and 2 big tie straps. I cut a nice little housign for it in my 99 fuel pump assembly so it fit snug, then just added the straps so it wouldn't pop out. It was a bitch to squeeze the whole unit into the tank though.
Give www.tacreationsusa.com and see if they have your part.. If THEY don't have it you could try www.speedautomotive.com but use them as a last resort.
Or you could look up a part and perhaps order it from GM.