cagotzmann

So I tried to use a 1982 gas sending unit for my LS3 swap. I know the tank is not properly baffled but this seemed as a good option to start.

Fuel line connections was not a problem, electrical connections not a problem, gas gauge tested and showed correctly based on float position, easy to wire in a aeromotive fuel pump and mount.

But I was not excepting this problem.


The float hits the bottom of the tank which on the gauge is about 1/3 full. I could bend the wire hanger but didn't think this would be a problem.

The video is with 15 liters (4 gallons) of fuel in the tank. Which is empty as far as the fuel pickup is concerned.

I should have checked this before installing. I am going to leave it for now and see how it performs before deciding a course of action.

But most likely will get a properly baffled tank with modern style fuel pump setup.

derekderek

what are you using for a fuel pump. the 82 setup does about 11 psi. the LS needs 58 psi.. now, the fuel line. it was made to suck fuel under slight negative pressure the length of the car. it has been there, vibrating, getting hit by rocks, corroding for 42 years. with the carb setup, if it pops a hole the fuel pump sucks air and the car stops running. now you wanna put 60 psi of fuel pressure in this old steel line. if it pops a hole now, the car keeps running while fuel is being sprayed all over the underside of the car. carefully routed fuel injection hose is something to look into.

cagotzmann

as stated above "aeromotive fuel pump" Complete new fuel line running down the driver side as required by the LS3. No problem with the engine running, just the 82 sending unit float system doesn't work as required. The float cannot drop far enough to read empty.

I would need to bend the rod to make it work. Surprised it hasn't come up before since many suggested using a 1982 sending unit for EFI Conversions. Or maybe my OEM 78 tank is an exception.

Buccaneer

Just out of curiosity, will a 82 tank fit in your car? It can't be that different, is it? If it fits, you WIN! They are being re-popped as well, but no inner bladder though. Also, fuel pumps are not rated by psi, but flow. It will either be lph or gph and then regulated to the psi required and governed by a certain voltage. The stock setting for a CF is 13psi and the pump flows roughly 40gph at 12v. He does not need or want that pump anyway to feed a LS motor.

carriljc

Just bend the rod. No big deal. You can then dial it in. I modified the hell out of my 82 sending unit to squish it into my 68 and even lopped off the level measurement contraption (I still have the old one from the bottom). You cannot really hurt it, and if you do, then you can just braze it back on. The sending unit I got is made of Stainless Steel and other than the crappy underside electrical connector (I ended up brazing and heat shrinking those onto the bottom) it seems built quite well.

cagotzmann

Is a direct fit for mounting, only problem I have is with the float travel.

This is the pump installed.
340 Fuel Pump, GM - Aeromotive, Inc (aeromotiveinc.com)

Mounted in the factory 82 sending unit. using a C5 corvette fuel filter regulator mounted near the driver side gas tank on the frame rail. I get 60 PSI at the fuel rails at the engine.

lionelhutz

I can't tell in your video. Where is the fuel level? The float shouldn't be at the bottom of the tank when there is 9 gallons in the tank. It should be floating in the fuel. If the float is dropping that low because there is no fuel then the pump would be sucking air. Or, are you pushing the float down??? The same tank is sold for 78-82 cars, so either the 78 or 82 sender would work the same in all those years with the same size and shape of tank. Maybe the arm got bent during the shipping and handling.

cagotzmann

added 4 gallons (error in previous post) 15 liters of fuel you can see on the pump sock its just touching. I found because of the fuel tank angle and the pump pickup there is always some fuel that cannot be picked up by the pump.

bluegtp

Also note, don't floor it for long somewhere around 1/4 tank or less. Took me a while (not expecting to starve it of fuel around 1/4 tank) to figure out what was up.

It works, but could definitely benefit from a properly baked tank.

4-vettes

Many, many people have put the 82 sending unit in 78-81's. If your having trouble with the fuel pump not sitting all the way on the bottom of the tank. Clearly you don't have something right. As per the float rod. seriously, bend it till you get it right.

cagotzmann

Never said I had a problem with the pump not sitting all the way on the bottom.

With 4 gallons of fuel you can see the sock for the pump is in fuel.

Nothing special about installing the sending unit, 1 gasket & bolts, just the float that doesn't clear without hitting the bottom of the tank. Never thought to check this while outside of the car. Bend to clear to get the gauge to read better.

4-vettes

O.K. perhaps I miss read something. And yes adjusting the float arm could take a couple try's in and out to get it just right.