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 Post subject: Rust in fuel tank
PostPosted: Thu Aug 03, 2017 8:25 am 
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Joined: Thu Oct 01, 2015 2:50 pm
Posts: 43
Here is a photo of my 280-Z gas tank interior taken through the filler tube hole. Inside there is some kind of can into which the gas return line for the fuel injection system goes. The tube high up in the tank is one of the vent tubes [I think].
Z-Guy


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 Post subject: Re: Rust in fuel tank
PostPosted: Thu Aug 03, 2017 8:43 am 
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Joined: Thu Oct 01, 2015 2:50 pm
Posts: 43
I don't know what happened to my earlier post with regard to fuel tank rust so I will try again.

I'm at the point where I have to do something with the rust in my tank so I can reinstall it into the car. I plan to loosen the rust in the tank by dropping nuts and bolts inside with some water, sealing all of the holes and shaking it around as I have seen people do on You Tube. With repeated shaking and flushing I hope to get most of the loose rust out.

I see some kind of can in the tanks interior into which the return tube from the FI system goes. Anyone know what the cans function is?

After cleaning I plan to use the Por-15 system to etch and seal the tank interior. Has anyone used this system with success?

Thanks, Z-Guy


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 Post subject: Re: Rust in fuel tank
PostPosted: Thu Aug 03, 2017 9:34 am 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12882
Location: CT
I've never seen that before. Except for your description of the return tube running into it, I thought you might be describing the fuel float itself.

Here's a couple exploded diagrams of various 280z fuel tanks (scroll down to FUEL on the left side). The only "can"-like object I see is listed as item #4, which is the fuel float. It appears on opposite sides of the tank in different years. Is that it? If it actually accepts returning fuel, it wouldn't be a float. In that case I would first suspect it's a filter, but there's nothing in the diagram which is called that.

http://www.atlanticz.ca/zclub/techtips/ ... iews/280z/

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 Post subject: Re: Rust in fuel tank
PostPosted: Thu Aug 03, 2017 9:47 am 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12882
Location: CT
In order to find your old posts (or anybody's), click on your PROFILE button in the lower left corner of the screen. That shows you the information you allow the Club to read about you.

On that screen click SEARCH USER'S POSTS and that will allow you to see the first few lines of every subject you wrote or responded to.

Looking at your history I note we discussed this under several titles; fuel starvation, rusty fuel tank and this current one. Also, you put one of them under the RESTORATION TIPS title. Maybe you're looking for it here but left it there?

8) :thumbs_up:

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 Post subject: Re: Rust in fuel tank
PostPosted: Thu Aug 03, 2017 10:54 am 
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Joined: Sat Jun 01, 2013 5:38 pm
Posts: 539
Location: Orange, CT
Z-Guy, don't bother with water. If you're keeping the tank then get yourself 5 or more gallons of apple cider vinegar from Wal-Mart. about $4.50 per gallon. Drain the fuel if you haven't already and air it out well. A few days open and even with air circulating through is better. Seal all openings and pour the vinegar in. Let it sit for 3-7 days or as needed depending on the rust level. Nuts are fine for breaking up rust but I prefer bb's because they're smaller. You can get them on amazon cheap. You won't be able to shake it with the tank full so you'll need to drain some first. During that time, turn the tank so all sides get soaked. A few days on one side then the next. After the time you will see all the rust is gone. Drain the vinegar back into the containers. You can see all the rust is now in solution with the vinegar. Thoroughly wash out the tank with hot water and baking soda mixture to neutralize the acid. Rinse again and uncover openings. Let dry or as before circulate air. I use a compressor with a air nozzle taped open and set the regulator to about 5 psi. After that use a claw type parts picker with some paper towels to make sure all water is out. You may get some flash rust back but don't worry about that. Once dry you can aply whatever product you want to seal. I like Red-Kote but POR and Eastwood have good products too. I have done several motorcycle tanks this way and it works great. This winter I plan on doing my Z tank.

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 Post subject: Re: Rust in fuel tank
PostPosted: Thu Aug 03, 2017 11:43 am 
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Joined: Thu Oct 01, 2015 2:50 pm
Posts: 43
Hello Frank
Thanks for the interesting link. In it fuel tank[post Aug. 76] appears to be mine. Unfortunately they don't show the tank innards.
Item#4 [fuel tank/sender] had been removed from the tank prior to my taking the interior photo.

The mysterious can that the fuel return line goes to appears to have a vent line coming out of its top. Could the cans function be to keep turbulence or foaming from occurring when fuel is flowing back into the tank?

I am hoping there is no filter inside the tank since there is no access for maintenance.

I find it strange that fuel goes directly from the tank to the fuel pump with no filtration. In digging around in You Tube I found a photo of a fellows car in which he had installed a plastic fuel filter between the tank and the pump. It seemed a little unsafe to me because stuff kicked up by the rear tire could fracture the plastic.


I checked out the profile and searched my posts with no luck. My original note was written yesterday and had been put into a draft. After editing it today I submitted it which is when it disappeared. No big deal.

Best, Guy PS...I am still looking for feed back info on the Por-15 system. I don't want to spend $65.00 on the kit and find out it is no good.


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 Post subject: Re: Rust in fuel tank
PostPosted: Thu Aug 03, 2017 12:29 pm 
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Joined: Thu Oct 01, 2015 2:50 pm
Posts: 43
Hello SurferD
Thanks for the input. I have been using white vinegar for removing the zinc plating on small steel parts prior to welding but didn't consider it for de-rusting. My son informs me that Home Depot sells cleaning vinegar that is slightly stronger than the stuff from Walmart which is a 5% solution I think. He also thinks it might be cheaper. I also like to use vinegar for killing poison ivy [I love to recycle stuff].

I drained all of the fuel from the tank last month, flushed it with water to drive out the residue and then left it in the sun all day to heat everything up. The tank is dry and in the garage awaiting the next step.

I find using bb's a little concerning since there seem to be many spots inside the tank where they could lurk and perhaps clump up at the fuel intake in the future. I was thinking I would take a count of the nuts and bolts prior to putting them in the tank so I could be sure of getting them all out.

I plan to bolt a couple of approx. 40" pieces of wood across the top and bottom of the tank with threaded rod and bolts. Then I will set the wood ends on saw horses so I can rotate and shake the tank without having to lift it. I haven't tried it yet but will let you know if it works and will send some photos.

For the drying step how about hooking a shop vacuum in blower mode to the tank filler?

Best, Guy


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 Post subject: Re: Rust in fuel tank
PostPosted: Thu Aug 03, 2017 12:52 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12882
Location: CT
I spent $115 for a large enough CASWELL etching and sealing kit to restore my 1966 Bultaco motorcycle tank (2.5gal). It was the second-best thing I ever bought for the bike. CASWELL is preferred and recommended by many restoration shops. I have visited Manny Dragonne's Classic Car restoration shop in Bridgeport and they use nothing but CASWELL. That makes me suspect CASWELL is the top of the line.

http://www.caswellplating.com/epoxy-gas ... ealer.html

Your Z needs enough to etch and seal a 17gal tank, but that of course doesn't mean you need 17gal of CASWELL. This $500 kit might be enough to do several tanks your size, so smaller kits might satisfy your needs. They mention POR-15 deteriorating after a time, which I have no experience with but certainly wouldn't want to have happen to anything I drive.

Many aluminum extenal electric fuel pumps have a detachable filter on them. Many years ago I bought a filtered stainless steel fuel pump and rigged up a converted 12v cleaning/filtering system for my giant fish aquarium. I routed the water thru so many external filters, the internal filter on the pump never needed cleaning.

Bryan Little uses one on his car, which is enough to convince me it's a good idea.

Don't feel you have to stick strictly with Datsun parts for something so universal ~ scores of brands make good filtered external electric pumps and in-line cleanable filters. It's all just 12v electro/mechanical technology mounted in a place people can hardly see unless they contort like pretzels. The amount of noise each electric pump makes will probably be your deciding factor. They make two types of pump; you will probably want the quieter rotary vane style.

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 Post subject: Re: Rust in fuel tank
PostPosted: Thu Aug 03, 2017 5:44 pm 
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Joined: Thu Oct 01, 2015 2:50 pm
Posts: 43
I went into the Caswell site and found that they have a sealer [1 qt.] for up to a 20 gallon tank for $79.99 +$20.00 shipping. In their instructions they don't mention anything about etching...just cleaning the loose rust out and rinsing. They claim that the product prefers to bond to a rough rusty surface. They also claim that it is thixotropic. Is there any problem with it flowing around inside the tank? I suppose I could use a hand sander to vibrate the tank surface to make it move. I will give them a call for more info.

So far my fuel pump is doing fine and I hope that keeps up. I guess after sealing the tank I won't have to worry about contaminated gas coming from it. I was just wondering generally about the filtration thing.

I started messing with the tank this afternoon and after rapping with a mallet and shifting it around I was able to dump a little less than a pint of very fine rust out. Some of it was small flakes but when I rubbed them between thumb and forefinger they broke down to fine powder. I am thinking my whole problem is just surface rust over a large area. The tank seems really solid.

On a positive side there doesn't seem to be any varnish build up in the tank.

Z-Guy


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 Post subject: Re: Rust in fuel tank
PostPosted: Thu Aug 03, 2017 7:05 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12882
Location: CT
["Is there any problem with it flowing around inside the tank?"]

Not sure what you mean by that. You have to roll the tank over in order to let the sealer reach all surfaces, so I guess the answer would be NO.

Just ensure you plug each functional hole with something which extends a short way into the tank. The sealer will form a really solid cover over whatever it touches, so if you don't stick something into the holes, they could seal closed. I've heard of guys (no pun) using wooden dowels and I used a fastening bolt. My bike tank only had the petcock hole to worry about (my filler neck had a long tube extending down inside the tank to prevent spills if I dropped the bike). I sized a perfectly matched carriage bolt up in there and just screwed it out when the sealer dried. Worked fine.

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 Post subject: Re: Rust in fuel tank
PostPosted: Fri Aug 04, 2017 1:03 pm 
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Joined: Thu Oct 01, 2015 2:50 pm
Posts: 43
Hi Frank
With regard to the flow inside the tank, I was concerned with the viscosity of the sealer since they mentioned that it was thixotropic which can approach the consistency of whipped cream.

All of the tubes in my tank have bends in them except the filler tube.

I called Caswell [1-855-caswell] and spoke with Jayson in customer service. I was told the mixed epoxy is the viscosity of honey and can't be thinned.

The cure has to be 3 to 5 days because of the alcohol that is added to our gasoline. I pointed out that I may not be able to get all of the extra epoxy out of the tank because of its shape. He said if the epoxy pools the cure time should be extended.

The working time for the mixed epoxy is about 40 minutes before it starts to gel [thicken up prior to hardening]

The color of the epoxy is amber and can't be tinted.

After roughing up with a handful of drywall screws the tank should be flushed with 2 to 3 pints of lacquer thinner or acetone [not one pint as in their instructions.

They don't recommend any etching on the tank interior. Once the thinner is dried go right ahead with the epoxy.

I asked if other than improper mixing how can I screw up and was informed improper prep can ruin the job.

The difference between the amber product and the colored ones is a special dye that they use.

Their product has a one year shelf life when unmixed.

After coating the tank interior and dumping any extra material I plan to blow compressed air through the vent and fuel flow tubes to make sure they are open.

Best, Guy


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 Post subject: Re: Rust in fuel tank
PostPosted: Fri Aug 04, 2017 2:17 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12882
Location: CT
Excellent research!

The description he gave you didn't sound like the CASWELL kit I used 5yrs ago. There was no trouble sloshing it around in the tank and only a small amount came out unused. My tank had #6 shotgun pellet holes in it and the CASWELL sealed them completely.

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 Post subject: Re: Rust in fuel tank
PostPosted: Fri Aug 04, 2017 3:17 pm 
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Joined: Thu Oct 01, 2015 2:50 pm
Posts: 43
Do I dare ask how the shotgun pellet holes got in there?


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 Post subject: Re: Rust in fuel tank
PostPosted: Fri Aug 04, 2017 8:26 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12882
Location: CT
No.

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 Post subject: Re: Rust in fuel tank
PostPosted: Sat Aug 05, 2017 12:22 pm 
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Joined: Sat Feb 01, 2014 9:21 am
Posts: 739
Location: Somers CT
:shock: :mrgreen:

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Somers CT



75' - 280Z - HLS30203249 - #304 Gold Metallic (stockish)
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