Fuel Filter? Or Plugged Tank Sock?

[OPELFIEND]

Just purchased a 73 GT, drove it over 100 miles and it ran like a top. All of sudden, with no warning, the thing loses power. Kind of chugged along, jerking. Pulled over, the thing dies. Starts right back up, good for another couple of miles, same thing. Had to finally have it towed. The car starts and idles fine. It will go a short distance, then loses power. No gas smell at all. Can anyone help me on this one? It has a new carb, new gas tank, all that. Would it possibly be the fuel filter?

[baronbors]

When you say new tank- do you mean brand new- never had gas in it, because what your describing is the classic plugged fuel sock syndrome. If it is a replacement tank from another car, you might want to do some reading on removing a fuel sock. Other than that, probably have a fuel filter clog. Pull the gas line as it goes into the fuel pump and see if gas drains out. If it does then see what type of fuel pressure you have withthe fuel line diconnected from the carb. That should isolate your problem- but I'll bet it is a fuel sock

[OPELFIEND]

It wasn't a brand new tank, but the man assures me it was clean when installed 5/06. It hasn't been driven a lot during the last two years, but has been started and driven a few miles routinely. Has electric fuel pump, new lines, everything. I had never heard of a fuel sock. What do you do, remove it? Does the tank have to be taken out to address this? I replaced the fuel filter, no improvement. Any help would be much appreciated. The thing runs great when it runs.

[baronbors]

Do a search for "screen + sock + tank" and you should find several post providing instructions for removing the sock.

[kwilford]

Moderator Note: These posts were split off to their own thread as topic didn't relate to original thread

[kwilford]

Moderator Note: These posts were split off to their own thread as topic didn't relate to original thread

ALTHOUGH, is it possible that the tank isn't properly vented? These cars use a sealed gas cap and rely on the tank vent system (including the charcoal cannister and a connection to the carb) to provide tank ventilation. If the tank vents were sealed or blocked, the tank will get pulled into a vacuum, and cause fuel starvation. Try removing your gas cap and go for a drive.

[opelbits]

Sounds like a good candidate for a glass fuel filter with the replaceable element to be put in-line (preferably down low, like between the engine support and the alternator. Easy to get to and see).

The guy said it was clean, how did he know? If you look inside the filler hole of a tank, and you see clean metal, everything is okay, right? Maybe not. If the tank sat with half a tank of gas, the area of the tank not filled with is exposed and can rust. So, guess which part of the tank you cannot see when you look inside?
You may have a bunch of loose flaky rust coming off the top of the tank. especially if it started being difficult after a hundred miles.

Maybe.

[GTJIM]

Here is the link to the original posting: http://www.opelgt.com/forums/13340-post2.html

Be aware that the pipe that comes out the bottom of the tank is often so rusty that it breaks off when being removed to do this de-socking.
Also make sure you have a new fuel filter between the tank and the fuel pump as there will be nothing to stop rust and gunk getting into the pump once the sock is gone.

For a quick and dirty short-term "fix" just try blowing back though the fuel line to see if you can dislodge the crap - if that works you know what you have to do ......

[baronbors]

I would rather have a root canal in my mouth than have to de-sock a gas tank but we all had to do it at one time or another. After mine was done- I put a metal fuel filter just before the fuel pump and a clear filter just before the carb- never had any problems with it again.

[OPELFIEND]

Gentleme, thanks for all your advice. Looks like I have some work to do.

[OPELFIEND]

When you say new tank- do you mean brand new- never had gas in it, because what your describing is the classic plugged fuel sock syndrome. If it is a replacement tank from another car, you might want to do some reading on removing a fuel sock. Other than that, probably have a fuel filter clog. Pull the gas line as it goes into the fuel pump and see if gas drains out. If it does then see what type of fuel pressure you have withthe fuel line diconnected from the carb. That should isolate your problem- but I'll bet it is a fuel sock

Well, it turns out the gas tank was rusty, so I had it cleaned and fuel sock removed. Runs great now, except, the gas gauge doesn't work. Any thoughts on this?

[ungermm]

It could be that the sending unit filament wire has rusted though (a common problem). But, first thing would be to make sure you have a good ground to the unit. An easy test is to put a grounded wire to the top of the sending unit and see if the gauge moves. You can test the tank gauge in-dash. Do a search of "how do you bench test gauges" by Destec to see how. If the test doesn't get your guage to move, then you might have bad connections at the back of the tank guage, but, pulling the dash cluster gauge panel out is not my idea of having fun. Jerry

[OPELFIEND]

The gauge worked fine prior to having the tank pulled. So it must be either a stuck float or the sending unit.

[namba209 (R.I.P.)]

Not necessarily so. you pulled the tank and re-installed it, could be you didn't get a good ground as was stated previously. I'd check that first. On my Willit?project during the restoration, I ran a separate ground wire just to the sending unit. Trons are funny that way. Somewhere on this site, J.J. Wheatley has a chart of what the gage is supposed to read in ohms at various float levels and also there is a post about disconnecting the wire at the sending unit and grounding it and watching the gage to see what it does. This is a recording, if you don't have a DESTEC schematic, you need one, just to be able to have a really good piece of art and to get all the neat little hints J. J. has included in his drawings.

[soybean]

Here is the Link that I think Ron was refering to. I did a search for the chart that was discussed, but I couldn't find it either. As Ron stated, it could very well be a ground. HTH,Jarrell

[baronbors]

When you say it is nor working- do you mean its stuck in the same spot or not activating after the key is turned on? If it is stuck in the same spot with the key on = float problem. If it is not moving at all = electrical problem. As others said, probably a bad ground.

[OPELFIEND]

Thanks guys. The gauge doesn't work at all. No doubt it's an electrical problem at the tank.

[OPELFIEND]

Would the tank have to come back off to fix the ground?.

[soybean]

No, just unplug the sending wire and take the bolts out and lift the unit out of the tank. Before I went to that much trouble, I'd get a known ground and ground it to one of the bolts that attach at the top and see what happens. If you do take the sending unit out, check it with an Ohm meter as per the link that was posted. The float could also be stuck, although you stated that it worked before the tank was cleaned. That's why most are believing it's just a ground issue. If that works, then check it (grd) to one of the 4 tank attaching bolts. If it still works then just run a seperate ground to one of the bolts. Hth, Jarrell

[OPELFIEND]

Thanks for the information. Man, you guys know your Opels. I have a long way to go.