I have an 81 Vette, can someone tell me if I can just pull the sender out the top or does the gas tank have to come out? Any other tips would be appreciated.

 

I have an '82 and it can be done without removing the tank. You do need to remove the fuel lid. BUT, it's pretty tricky, just keep moving it around until it goes. As a guide, notice where the lines are on the sending unit so that when you are done twisting and turning, they end up in the right place. And be carful not to force things, you'll end up bending the float lever. And you'll probably scratch up the paint inside the opening. But it CAN be done.

 

Thanks for the help. Hopefully my part shows up by Friday.

 

In addition to what kanvas lists...disconnect the battery and once you have removed the lid, you will remove the rubber boot. Also, disconnect the sending unit wire...its a spade tipped if I recall correctly. You have got three lines, an emission line (left side from rear) and two fuel lines (main and return).

If you are successful in removing the rubber fuel line and the sending unit, you are doing good and in luck. The sending unit will somewhat screw out due to the curvatures of the sending unit...you'll see. Try to remove it first before proceeding with the following which makes it a more challenging project.

You may find the fuel line rubber hoses do not want to slide off...they have been on there for years. Have fresh rubber fuel line to replace the existing. I had some difficulty removing the rubber fuel lines on one 78 with 56k miles and ended up lowering the tank...not dropping, just loosening the straps so I could get a art & craft knife to slit the rubber. Than removed it. You can recycle the color coded clamps which also makes it easier to secure the new rubber lines instead of screw clamps. If you have screw clamps...someone has been in there before. Did 78 several years ago on two different 78s. At this point, also look for your buildsheet.

Here's link to an article about removing and repairing the fuel tank sending unit:

Fuel Sending Unit Repair

Hope this helps!

 

If it can be removed from the top as the '82 - which you need to confirm with your shop manual - it is easy and not at all tricky. After unbolting it and removing the wire connector three hoses, turn it to the right (clockwise) 180 degrees firmly as you pull it out. I read that tip on this forum and if it takes you more than 10 seconds to twist & pull it out you're not twisting it the complete 1/2 turn as you pull it out. In other words the 12:00 bolt when you start will be at the 4:00-6:00 position by the time it is out. Then the first thing you want to do is seal up the hole. Remember to buy a gasket as I was told I didn't need one which is incorrect. And, have a fire extinguisher close by. First spray the floor/filler area with a mist of water with a nearby garden hose to minimize any chance of static electricity. Call me paranoid. Follow all the previous poster's tips. Gotta admit that this is a classic satisfying, money-saving C3 DIYer job.

 

Appreciate all the help. I'll post when I complete the job.

 

The part showed up today and went in in about an hour. The tips really helped. Gauge works perfect now.

 

The part showed up today and went in in about an hour. Thanks for all the tips. Gauge works great.

 

Hunt4cleanair, thanks for posting the rebuild article. I would like to take on this project next weekend and will be ordering parts this week.

In my case, I'm interested in the check ball that is meant to keep liquid from passing to the charcoal canister. It looks like I'm getting liquid fuel out of that port. And, while I have the sending unit out I will be rebuilding it.

I'm hoping that by replacing the hoses and the sending unit gasket, and freeing up the check valve ball, I will eliminate the smell of raw fuel that has lingered around my '80 since I bought it last September.

Would it be possible to get a copy of the article with all the text included? The bottoms of most of the pages are cut off.

Many thanks!

 

I take it the check valve is not loose. I'll be curious to learn what you find so keep me posted. The hoses can also get cracks in them that can mimic similar fuel evaporative effects!

A good project for the Corvette enthusiast DIYer with outcomes that are self-satisfying. Good luck!

Yeah...see what you mean. Those were days before an editor would send the author a full-color proof that could be used online. I had to cut, paste and post.

Here is the source and citation. I'll have to find the copy in my storage area...its not readily available.

Restore Your C3 Fuel Tank Sending Unit, Corvette Enthusiast, October 2006

 

I have a '79. Would I be able to pull mine out of the top?

 

I rebuilt the sending unit yesterday. I'm seeing a resistance range from 5 to 95 ohms instead of the 0 to 90 ohms specified in the article. Unless somebody sees a problem with that, I'm going to go ahead with it.

I haven't disassembled the check valve yet. The check ball rattles around fine, so there may be another issue here.

What is the inline tee on the emissions line side of the tank for? My problem may be there.

COOLTED, I have never worked on a '79, but in my '80 shop manual it describes being able to remove the sending unit without dropping the tank as a new feature.

 

That's interesting...range is the same but scale differs by 5 ohms. Not sure if that is significant or not.

The 78 AIM shows a tee and the tee connects the fuel sender unit via emission hose while the other side connects (via short hose) to an emission line that routes to the canister. This is directing fuel evaportive fumes back through the line to the carb.

So is one end of the tee open-ended?

 

Sorry, I wasn't clear. The tee is mounted on the fuel tank. One side goes into the tank. A short hose connects it to the check valve on the sending unit. A second short hose connects it to the line to the charcoal canister.

 

I don't believe the "one side goes into the tank" actually has a port that extends into the tank. It should only mount and is either welded or soldered onto the tank acting as a pedestal to support the ports to the canister and check valve.

If it has separated, it should be reattached or if a hole, than repair required.

 

Okay, so what is that thing then? There isn't anything like it on the other side, so it must have a purpose. Maybe it's another check valve?

-Doug

 

Doug

My curiosity is piqued as well so I contacted Joe Lucia at the NCRS forum who is our go to guy for unusual or lesser known parts...of which this tee is one. We know it was used 1978-82 for emission systems but the configuration is puzzling. He contends that a tee would have three ports and the pedestal mount is a port, suggesting that fuel vapor vents through the port and down the emission line. My point is why then do we have a check ball valve that has the same purpose but prevents liquid fuel from sloshing into the emission line?

Well, he did not have one in his part inventory so tracked down an NOS and awaiting its arrivial. While this may not answer the question what it does, it will tell us if the tee has a third port and how it mounts. Does it screw in or is it welded?

Not sure if this helps but if it has three ports, and the mount is cracked, it will emit fuel vapor which you smell!

 

Doug

Well the tee is a three port fitting. I have attached a couple of photos for your study but note the sealer on the threaded portion.

It is possible that there is a pressure vacuum valve in the tank below the "pedestal" that the fitting threads into. It would be easy to check if you access to the tank. Simply remove the fitting and insert a rod into the opening. If the rod bottoms, then there's a pressure/vacuum valve there. If not, then there's not.

Your emission leak could very well be where the fitting threads into the tank and the fix could be as simple as removing, use some sealant and rethread.

Let me know what you find. Hope this helps!