Fuel Sending Unit Question

[Rustallion]

Hello everybody.
I have a quick question relating to replacing my 1984 Oldsmobile Cutlass Supreme (V6 3.8 )'s fuel sending unit (trying to fix the gas gauge reading improper). When I looked online at Advanceauto's website, I saw that they had two sending units made by the same company with similar prices. Both are pretty much the same except for that one has three outlets and the other one has two outlets. I'm curious about which one would fit my Cutty correctly, I would hate to buy the wrong one. So, if anyone could help me, I would be very grateful. :}
Thanks!

 

[GBODYLS3]

I can tell you that my cutlass, which is a 1988 has the three tube sender. My monte carlo also uses the three tube sender. If you want to be positive what you have, jack the car up and look. There should be a sheet metal plate attached to the to the body in front of the gas tank. under that cover is where the connections are made to the sender. you could see how many lines are there.

 

[Fox80]

On my 80' Cutlass the sending unit has two pipes, you can tell easy enough before you buy it I think. Look under the car at the front of the gas tank, two hoses coming out you need the two pipe unit, three coming out you need the three pipe unit. Are you sure your sending unit is the problem, I went through this same thing on my car, and it ended up being corroded pins where the gauge cluster plugs into the dash. Also clean the ground for the sending unit its next to the rear part of the gas tank strap on the left side on my car.

 

[spidereyes455]

In my experience all 6cyl cars used the 2 line sending unit, one for fuel feed to the engine and the other is for the vapor canister and 307 cars used the 3 line, one for fuel feed one for the vapor canister and the 3rd is fuel return.

 

[Rustallion]

Thank you all very much for posting on my topic. You guys all provided me with helpful information.
I'm definitely going to try checking under the car tomorrow to see which one it needs.

Are you sure your sending unit is the problem, I went through this same thing on my car, and it ended up being corroded pins where the gauge cluster plugs into the dash. Also clean the ground for the sending unit its next to the rear part of the gas tank strap on the left side on my car.

I'm not 100% sure it's the sending unit, but from the symptoms that the gas gauge has presented to me, it seems like an issue with the sending unit. My gas gauge works to an extent, example: if I fill the car all the way up, it will read around 60% on the gauge but as soon as the tank is half-way down it will read empty or 5%.
Also, I already checked the grounding and actually cleaned it up. Nothing changed.

 

[Fox80]

Maybe it is the sending unit then, I changed mine after I cleaned the ground only to not have it work right still. But mine would just drop to empty on its own. That's when I found the corroded pins in the dash, more than likely bumps in the road were making it lose contact. Easy part to change, and it's cheap just try it and see what happens

 

[GT_80]

check the ground at the sending unit and at the gauge.

If you get a new sender, You will need to match the sending unit to the fuel pump- if your mechanical pump has 3 ports, you need the three port sender. If the fuel pump has 2 ports, you need the 2 port sender.

 

[Rustallion]

I just checked under my Cutlass Supreme and it's a two line sending unit. So, I'll be picking up a new one shortly.

That's when I found the corroded pins in the dash, more than likely bumps in the road were making it lose contact. Easy part to change, and it's cheap just try it and see what happens

Thanks once again for the information. I'll definitely look into that.