Fuel Problem!

[john4856]

My gt has started running out of gas when you let the tank get below 1/2. I have a new weber and new fuel filter on it. The gas gauge seems to be working correctly. It also seems to only happen when driving uphill, It will starve for fuel going uphill and clear up and run fine going downhill. Any help would be appreciated, John.

[namba209]

John, the shape of the GT gas tank should not cause that problem with a half tank of gas. Do you know if the fuel sock is still on the fuel pick up line in the tank? There could be a remote possibility if it is still there, that it is clogged near the bottom of the tank and only the end portion is clear to deliver gas to the line. If the sock is still in the tank, run a search for how Otto, aka Tekenaar, has designed a way to remove the sock. It's better than removing the rear shelf and taking it out through the sending unit hole. HTH.

[john4856]

No i do not know if the sock is still on the pick up or not. What keyword would i use to search for the post you mentioned? John.

[baz]

tank sock or sock should do

[RallyBob]

Try 'fuel sock', that turned up two pages.

[john4856]

I found it thanks. Is it possible this sock is the cause of my problem? Car runs fine with half tank or more of fuel, And the sock appears to be in the bottom of the tank. How long is the sock?

[john4856]

The post by Tekenaar seems to indicate that the sock can be removed thru the fuel fitting on the bottom of the tank, is that correct?

[BQS4]

John;
That is correct, I think here's a drawing of the tool and how to do it on that thread also. Where is Byron, GA? I'm in Snellville, GA

[namba209]

John, I have no idea how long that sock is, mine was in pieces when I took out the quantity sensor hole after I took the tank out for restoration. My thoughts on your original post was the sock could possibly be floating upwards in the remaining fuel and the unclogged part of the sock could have been above the fuel level in the tank. Another possibility, based on your description of the problem, could be trash in the tank blocking the fuel outlet when you go up hill, but that's kinda out there, because you said it happens at 1/2 tank or less. A real head scratcher there.

[john4856]

Can the sock be inspected thru the sending unit hole with the tank still in the car?

[john4856]

Originally Posted by BQS4 John; That is correct, I think here's a drawing of the tool and how to do it on that thread also. Where is Byron, GA? I'm in Snellville, GA

Byron is about 10 miles south of Macon.

[Bo Mows]

Is your filter before or after the pump? Try this. With the car up on jacks on the front, start the car see if it stalls, if so, turn off the car and pull the fuel line from the bottom of the tank.If it runs out then you know it's not tank related. Then pull the line before the filter or pump, which ever is closet to the tank. If gas doesn't run out at a steady stream, then there is a blockage of some type. Since the feed hole is below pump level, believe me it WILL run out of the fuel line at the pump (don't ask how i know). If it runs out and your filter is between the tank and pump, pull the line off at the pump. It could be that a full tank is enough gravity pressure, that it's pushing passed a blockage and a half a tank of gas, the pressure decreases (you get the idea). You could also have a vaccum in your tank from a partially blocked vent tube. JM2CW


Bo

[duaneb]

My 73 was doing the same thing when I bought it. After I dug the sock out of it and installed a filter in front of the electric pump the problem went away, but it sure was a frustrating 850 mi trip home to Oregon from Utah, had to stop every 150 miles for fuel.

[namba209]

John, from personal experience, you can't see a lot of the sock from the quantity sensor hole, but you can see some of it. It may not even be possible to do from inside the car, IDK, my tank was out already when I took the sock out of it. One thing to try to see if the sock is still there, is run the tank MT or close to it, so as not to waste any fuel, pull the fitting out of the bottom of the tank and stick a small long skinny screwdriver up through the fitting. If it goes all the way through the fitting with no resistance the sock is probably gone.

[john4856]

I managed to tear the sock up pretty good but i could not get it thru the hole. Does the fitting that the fuel line goes on unscrew out of the tank giving you a bigger hole to work thru?

[Dmcbrass]

I have seen bad fuel pumps do this. A full tank of gas will pump easier than a half full tank.

[spdkilz02]

yeah it does...

[john4856]

Originally Posted by john4856 I managed to tear the sock up pretty good but i could not get it thru the hole. Does the fitting that the fuel line goes on unscrew out of the tank giving you a bigger hole to work thru?

Does anyone know the answer???????????????????????????????????

[Bo Mows]

I managed to tear the sock up pretty good but i could not get it thru the hole. Does the fitting that the fuel line goes on unscrew out of the tank giving you a bigger hole to work thru?


If you unscrewed the fuel line so that there is nothing but a hole on the bottom of the tank, then the answer is NO, there is not more you can do. BUT, if there is still a short fitting still sticking out the bottom of the tank then YES you can unscrew it but it's really is not much more hole to work with. The sock is made out a nylon plastic material. If its degraded enough it will just crumble to pieces when you try and pull it out. HTH

[Emtee]

This seems to be the right thread to ask this. I've taken the tank out of the Arizona Opel I recently got and have removed the sock (brittle and clogged with dessert dust!) Now the question is "Do I need to replace it?". The tank is utterly rust free so I'm having the lining debate, I'll most likely do it while I have it out. Although it seems to be a bit of a drag to touch a 'shiny' piece of Opel!

Mike

[soybean]

I don't think the sock is replaceable. I wouldn't even try to.
Lining it depends on whether you are satisfied it won't leak or has holes that you can't see. I lined the gas tank for the next one using PORs tank liner. I used it on a military vehicles gas tank that dates back to the early 60s, and haven't had any problems with it since it was done 5 years ago. Just my thoughts on the subject. Jarrell

[RallyBob]

Originally Posted by Emtee This seems to be the right thread to ask this. I've taken the tank out of the Arizona Opel I recently got and have removed the sock (brittle and clogged with dessert dust!) Now the question is "Do I need to replace it?". The tank is utterly rust free so I'm having the lining debate, I'll most likely do it while I have it out. Although it seems to be a bit of a drag to touch a 'shiny' piece of Opel! Mike

The sock is simply a 'pre-filter' to prevent the fuel pump from ingesting any foreign debris. If you install another fuel filter before the fuel pump (factory or otherwise), then you will accomplish the same thing. I always like to run two fuel filters on my vehicles, one before the pump, and one after the pump.

Bob

[GTJIM]

The GTs have so many 'gunk & rust' in the fuel problems that two filters are just enough. Put one back by the fuel outlet on the tank to prevent lumps getting into the fuel lines and the pump. Place the other filter between the pump and carb.
Be sure to open up the fuel line and blow any rust flakes out or they will get into the filter (so it is best to use three filters - the extra one just in front of the pump, between pump inlet and the line to the tank.
Put the filters where you can see them to easily check that they are not becoming blocked too.

All this beggars the question - that you have a fuel tank removal, cleaning, sealing (with POR-15 or similar tank sealer) and replacing ... in your near future!