I have an 85' 2m4 with a non working fuel guage and I just bought a working fuel sending unit out of an 84' 2m4 to fix the guage in my car. But the wiring harness is different, my 85' has a single 3 pin connector and the 84' sending unit has one 1 pin connector and a 2 pin connector. I just need to know which wire does what on each harness, so that I can splice the connector from mine to the new sending unit and still have my fuel pump work and now get my gauge to work.

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It's a never ending project... That i might not even get to start

bump

I'm sitting here @ work having my lunch thinking about your situation. I don't have a service manual here but....
..I'm thinking that you should be able to follow the wires on the sending units up to the plug and figure out where they
plug into the car side plug(s).

I had to replace my sending unit a couple years ago and ended up with a similar issue. But instead of swapping out the complete
unit I just pulled the sending unit off and soldered it onto the tube of the factory part. It works!

For some reason I want to think that the sending unit used an orange wire, or white with orange tracer? I could be wrong.....
I'll dig out my service manual tonight @ home and check.

OK, well the 87 manual says that the tan/white wire is for the fuel pump. That will carry +12v.

[This message has been edited by 86_IRM_TURBO (edited 09-17-2007).]

Okay so then the pink wire would be for the guage? How could i test the sending unit to see it the float works properly before i put it in the car?

I tested mine with an ohm meter. If you connect it to the sending unit and move the float through its full range you should see it change as it moves. I was not on this forum when I did mine so I think there is a nice tech article on the Cleveland or Toledo club website on exactly how to set it B4 installation. These things are known to be far from accurate.

If you can't find that article let me know & I'll find it. I have to go to a plant over in Lansing for the rest of the day and measure
some cars coming off the line over there so I'll be gone the rest of the day. I'll check back tonight from home.

Hey thanks for the link. It seems to me that when i try to do that though my ohm meter just shows infinate resistance. But the guy I bought it off of told me that it was deffinatly working in his car he just couldn't use it for the V6 swap he's doing.

You can leave it out of the tank & plug it into the car then key the ignition on and see if the gage moves when you swing the float up and down.

Just a thought.

i pulled that sending unit from my 84. the sendinf unit and my gauge were working fine when i started the tear down for my V6 swap. it's really odd what FieroGuy9890 is seeing with the ohm test, especially since i know it was working. could just having it sit outside of the tank ruin something? it was on a shelf for a few days before it was shipped out. i will refund the money for the unit, but i would still like to know what is wrong. i have a V6 one that has been on a shelf for some time now and i would hate to think that it is ruined as well. any other ideas on the issue?

quote Originally posted by shawnkfl: i pulled that sending unit from my 84. the sendinf unit and my gauge were working fine when i started the tear down for my V6 swap. it's really odd what FieroGuy9890 is seeing with the ohm test, especially since i know it was working. could just having it sit outside of the tank ruin something? it was on a shelf for a few days before it was shipped out. i will refund the money for the unit, but i would still like to know what is wrong. i have a V6 one that has been on a shelf for some time now and i would hate to think that it is ruined as well. any other ideas on the issue?

The way I understand it is the replacement one is not nessesarily bad. He was asking about the wiring because it was a different plug configuration on his than the repacement part. THEN, I think he just wanted to make sure the gage/wiring worked before he re-installed the tank.

I could be wrong......

he mentioned that he is seeing infinate ohm readings though. that's the part that confuses me. it should be a range, like 0-something, shouldn't it?

You have three wires, one is for the fuel pump, one for the sender and one is ground.

On the 84 you might think the connector with two wires would be the sender and ground but it's not if I recall correctly. I seem to remember the single wire was the ground and the other two had the fuel pump and the sender on it. Make sure you don't hook the fuel pump up backwards...it will run backwards just fine, but it won't pump gas. Don't ask me how I know this.

Check the resistance between the sender and ground, it should vary between 0-90 ohms....(actually you never get zero but something less than 10 ohms.) If you are not sure which is the sender you have a 50/50 chance, try the other one.

[This message has been edited by jscott1 (edited 09-20-2007).]

Yeah I'm still playing around with it to try to get it to work. I'll have to keep checking the wires, but by all the wiring diagrams I've seen the pink wire is the one for the sender, but they aren't year specific diagrams. obviously black is ground. And I have disconnected the sender wire from the rest the harness before it leaves the tank and I'm still getting infinate resistance. Still hoping to figure something out.

maybe some moisture or dust got in it from sitting? try a low pressure compressed air to blow things out. i'm just throwing thoughts out there.