Gunk or something in gas tank!

[Decoy12]

Hello everyone, Z newbie here again requesting help. I got my Z running again although it was running very, very poorly. I bought it back in December and it had been sitting since '03. The previous owner said there was old gas in the tank and so I drained it, filled it back up and after changing everything from the plugs to all the 'pumps' in the engine bay, I ran it for a while. I recently changed my fuel filter because my Z was not running, seeming to be starved of fuel (delayed response when stepping on gas, 'choking' and jerking when I floor it.) Anywho... I was very surprised (not in a good way) when I removed the fuel filter I put back in December, when I noticed it weighed about a quarter pound. Inside there is all this build up of gunk or something. It is brown and it almost looks like modeling clay, although it is soft like a paste, probably because it was mixing with the fuel. I know I need to clean out my tank, but I was wonder if:

1. Anyone knows what this gunk side is? and

2. If it would be an easy DIY to clean out the tank?

Thanks in advance for all of your help!

[d240zx2]

The most effective way would be to drop the tank and send it out for cleaning.

You can continue to "dilute" the crud, but that will take a lot of time and a lot of gas and a lot of fuel filters.

[mlc240z]

Agreed.

If it's been sitting and you can see settling in the filter, it's probably in the lines: if it's in the lines, it's probably in the tank.

You run the risk of sucking it up and clogging the lines even further or completely.

Supposedly, a radiator shop will accept it and should be able to 'boil out' the gas tank for a reasonable amount of money.

[dclamm]

I went through this on my recently purchased Z that sat for a long time. I dropped the tank and tried to drain the gunk, after a week upside down and spraying with various things it was obvious it wasn't all coming out. Paid $100 to have it cleaned at the radiator shop and lined with POR15 tank liner.

I spent many hours trying to get the gunk out of the hard fuel lines. At first the line was completly clogged but I kept spraying carb cleaner from the engine side and blowing it through and it eventually came out clear. What a mess! It was in the carbs too, so I got a set of ZT carbs cause the stuff had stuck everything up.

Good luck, hope you're not in as bad as shape I was.

Dave

[beandip]

One of Our Club members was having problems with crud in the tank and Her husband cleaned and used POR-15. He told me that he had followed the instructions from POR and coated the tank. In abut 6 months the POR began flaking off and clogging the filter. He was able to find a newer 240 tank and how all is good. I had a conversation with Z Therapy owner. And the upshot is don't coat the tank! The stuff will come off and there is no way to completely clean the POR off once it is in there.

Steve said that he has had to cut the tanks open and scrape them clean , weld the panel back on and he has them cad plated . for what its' worth this is the info I have. I have used POR on other stuff for years and am a true believer , but not inside a gas tank. I hope you have better luck. 240 tanks are becoming imposable to find.

[Jeff G 78]

I think POR-15 is as great as long as the instructions are followed EXACTLY. Cheat even the slightest bit and it will fail. I have done two Z tanks and both are doing fine so far. One was done a year ago and the other is going on four years. To do the job right, it takes about a week of back breaking labor. On both of my tanks, I had to add many pre-cleaning steps prior to even starting the POR process. I rinsed the tanks with water and lengths of chain at least 50 times first to get the majority of the rust out. After the water only rinse, I used water and muriatic acid to further prep the tanks for the actual POR treatment. I'm pretty sure I did a thread on it last fall. I'll look around and post the link to the thread when I find it.

EDIT: I must not have posted pics. Here is my 260 tank before and after POR-15

This is the inside of the tank after the Z sat in a barn for 15 years or so

After a few water rinses, this is what I got out

After a week of cleaning, here is the same tank inside ready for the sealer step

Finally, after sealing

Edited July 1, 2010 by Jeff G 78

[Decoy12]

Thanks for all the replies guys! Sorry for the late response, I was being notified of all the responses by my email. Anyway I got another fuel filter, but at $6 its getting kind of expensive. I thought about diluting the crud, but it won't fix the problem in the long run. I am thinking also that running the car in such condition wouldn't be good for the carbs or the engine. I might as well take a look down there because I need to replace the filler hose thats leaky... Thanks for the replies and I will keep you guys updated.

[ncolz]

I went through the same thing on a '70 that had sat for a long time. Ended up dropping the tank and cleaning it out. Now it seems to run out pretty well. I'll be sure to drain the tank next time I park it so it should start up easier next time.

OK - thinking out loud here. I wonder if opening up the drain plug, draining the tank, then hitting the inside of the tank with a pressure washer would clean out a moderately dirty tank. That might be easier than dropping the tank - then again, it might just make a hell of a mess and then means dropping the tank while rolling around in a bunch of cruddy water. :-\

[Decoy12]

Hey guys its been about 3 months now since I have been trying to solve this issue... I finally go the $$ to have the tank cleaned... After trying to clean it myself with many different solvents I had no real luck. I think the hard white stuff on the inside was calcium (according to the guy that cleaned it). Now I got some por-15 and coated the inside and it looks so much better now. I am about to attempt to place the tank in right now... wish me luck!

[Darrel]

My 240 sat for 14 yrs when i bought it. I knew the tank had crud in it but wanted to get it out on the track before dropping the tank and replacing the vent hoses. I went through about 2 dozen fuel filters.

After the track day I dropped it and took it to a car wash. The varnish that was in it came out in small sheets. The only spot I couldn't get to was behind the baffle. The inside of the tank still looked new. I still have a fuel filter before the stock electric pump as well as the one before the mechanical pump. I haven't had to change any of the filters for at least 5 yrs.

Moral of the story, if you bought a car that has been sitting, one of the first things you need to do is drop the tank and clean it out.

[cygnusx1]

My '72 sat for 23 years with gas in the tank. After draining out the molasses-like fuel. I dropped the tank and brought it to a tank shop. The crust was so bad that the shop did not want to mess with it. I found a better, cleaner tank, and then used a DIY tank cleaning and coating kit from KBS. http://www.kbs-coatings.com/ It worked well but you MUST follow every step exactly. Watch their videos. They are helpful.

BTW The gunk is probably a varnish formed from old fuel.

Edited October 17, 2010 by cygnusx1

[Decoy12]

OH MAN DO I HAVE BAD NEWS Next to the fuel sending unit there are supposed to be hoses, one above the other. So everything was going well putting the tank back in... suddenly one of the metal "pipes" came clean off the tank! I am not sure what to do right now? Do I epoxy it in? Do I solder it in? I am not sure if I could solder it because I am not sure if the tank liner is flammable or not. I was so close to getting my Z back on the road Major Bummer!