Allright heres the deal, I have been battaling a fuel gauge issue since I bought this car.

First i Found that somebody before has already tried to fix this problem. So when I replaced my fuel pump I looked at the sending unit and found that it was broken so I installed one that was from a 2000 malibu because it was free and the factory one was over $300!

Now I know the newer one is supposed to read from 35 ohm to 235 ohm I think. Well right now I have a multimeter on the pink and black wires behind the back seat and it reads, but when I start the car the meter won't read in ohms only in volts and I get 8.5 volts. Well pretty much I want to get good ohm readings on full and empty so I can buy an auto meter gauge that reads the right ohm value so any help on this would be great.

If you need this info my car is an 85 with TPI Also I have a 92 rs in my garage for parts and the gas tank is almost out its alot of work to get that out. I really don't want to have to pull mine out again if I don't have to.

 

I believe the 1985 instrument used a 0-90 ohm sending unit. I doubt that you'll get one of the newer sending units to operate it properly.

 

Yeah I know the old sending unit was from 0-90 ohm, but my idea is to see if the one I installed from a late model chevy is in fact reading the correct ohm value on the empty and full which is 35-235 ohm but I can't get an ohm reading when the car is running only voltage. Right now it reads 51 ohms when the car is off and 8.5 volts running.

Anybody know of an easy way to fill the tank and then empty it without running the fuel pump. I dont think I can siphon it beause of the safety valve.

Also if anybody wants to know auto meter sells a programable fuel gauge but its like a $100.

 

You are not supposed to get an OHM reading when you have the car running, only voltage. You should only get an OHM reading with the car off and you have stated that you are getting 51 OHM's with it off. If you want a quick way to drain fuel tank without running the fuel pump, disconnect the line at the in-line filter and let it drain. It might take awhile to do it.

 

On your arm, clothes, undeside of the car & floor

3rdgen fuel gauge also only reads 0 to 90 ohms. With your new sender, if what you state is correct, empty at the sender will show almost ½ tank and ¼ tank reality will show full on the gauge... not as if anything of that useful but, I said it anyways

 

JC Whitney has a 0-90 ohm "universal" sending unit that can be adapted to replace the stock 3rdGen sending unit for about $17. Here's the link:

https://www.thirdgen.org/forums/atta...g?d=1090917955

What I'd do is attach just the sending unit portion to a mount on the original tank assembly by welding or bolting.

 

while we're on the topic.... the pink wire is the signal wire, the black is ground, and the brown should be hot, right? Well my brown wire isn't hot, any idea where this thing goes? I tried following it back but no good.

 

Sure,
The brown wire goes from the fuel tank to a connector on the bulkhead behind the rear seats, down the left side of the car, across under the dash to pin "D" of connector C207 which is located near the ECM. It then becomes a tan/white wire and goes into a splice with 4 wires coming out of it. One goes to pin "B2" of the ECM. one goes to pin "C" of the MASS AIR FLOW relay, one goes to pin "C" of the fuel pump switch, and the last one goes to pin "A" of the fuel pump relay. Hope this helps!!!!!!!!!!!!!

 

hmmm.... I found a brown that ohms out to the wire in question. it's going into a connector just before going through the firewall, behind the clutch pedal. Funny thing is - there is no pin in the other side of the connector. Perhaps this is on the other side of the splice you mentioned Trickster.

This brown wire was originally used for fuel pump power? I guess that would make sense, and now that I've yanked the ecm there's no connection. My fuelsafe fuel gauge sender requires a 'hot' wire as well as the ground and signal wires that the factory uses. I guess I'll try hooking the brown wire up to an accessory on, and use that wire to power my sender.

 

Thanks for helping me out But I ended up pulling the tank down and putting in the sending unit I pulled from the 92 in my garage. I know get an ohm reading of 28 ohm with about 8 gallons in it. Now I think i burned my gauge up with wrong sending unit it the tank because it goes to E. I should get my auto meter fuel today so I will found out later.