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I have an 84 spider veloce. It has a brand new gas tank, fuel filter, 2 new fuel pumps and my mechanic found a bunch of rust in the tank and the fuel was brown. I ordered a new tank, fuel filter and pump and noticed that I did not have a rubber gasket on my fuel cap. Could this be the reason for all the rust?

The car was put together in the spring with all the new fuel related parts. After about 200 miles it started choking and we found these issues.

The seller of the fuel tank says all the new tanks for this car are made by the same manufacturer and are uncoated. I plan on using stabil 360 from now on. Is this enough or is there something better?
 

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I have an 84 spider veloce. It has a brand new gas tank, fuel filter, 2 new fuel pumps and my mechanic found a bunch of rust in the tank and the fuel was brown. I ordered a new tank, fuel filter and pump and noticed that I did not have a rubber gasket on my fuel cap. Could this be the reason for all the rust?

The car was put together in the spring with all the new fuel related parts. After about 200 miles it started choking and we found these issues.

The seller of the fuel tank says all the new tanks for this car are made by the same manufacturer and are uncoated. I plan on using stabil 360 from now on. Is this enough or is there something better?
there are a variety of products used to coat fuel tanks. the better ones come from the aviation industry and are expensive, others come from the automotive restoration industry and are less so altho somewhat less reliable according to reviews and depending on who you ask. if you are saying that your new tank is simple mild steel with no galv or cad then its going to rust pretty quickly just from general condensation and the water vapor present in the air but I would be really surprised if that's the case. are you really saying this tank is just mild plain mild steel with no surface treatment what so ever ? if it is , I would coat the interior with one of these products before use for sure... and that would tell me that that tank is a pretty junky product.
 

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Someone wrote a detailed post a couple of years ago about cleaning and sealing a rusty tank. I think that the first step was after draining the tank pour in some gravel and shake the tank so that the gravel knocks off all of the loose rust. Empty out the gravel and pour in phosphoric acid - he named a good source, to convert the remaining rust. Then rinse it and treat it. He may have recommended the POR15 product. You should be able to find the post with the search engine.
 

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there are a variety of products used to coat fuel tanks. the better ones come from the aviation industry and are expensive,... Can you direct us to a known to be superior aviation product,I feel that extra money in this area is well spent
 

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there are a variety of products used to coat fuel tanks. the better ones come from the aviation industry and are expensive,... Can you direct us to a known to be superior aviation product,I feel that extra money in this area is well spent
not from recent experience. the last company I used was a company called " wet wings " in California somewhere but that was 15 or 20 years ago. i'm sure if you start googling , after a bit current suppliers will show up. and I am equally sure that with the current epa regs , the chemistry of all that has changed significantly as well. there is a publication called " trade a plane " that is a good source of info.
 

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I've de-rusted several tanks for my motorbike. Best approach for me has been:

Drain tank and air out for a couple days

Plug up any ports, and fill with a gallon of Prep N Etch (phosphoric acid) -



$15-20 at Home Depot

Leave acid in for a couple hours, rotating the tank every 20-30 minutes to keep coating the inside, unless you bought 10 gallons to fully fill the tank (which would be pretty dumb).

Drain/strain the acid back into the jug - because you can reuse it! :)

Rinse the tank with some water, followed by some WD40 to clear that out. Then treat with your favorite sealer. If you don't have a sealer handy or need to wait a few days to get one, slosh some oil or oil/gas mix in the tank to deter any new rust.

The phosphoric acid works great on rust, and leaves a coating to prevent immediately flash rusting when you drain it, unlike vinegar. AMHIK

For sealers, I prefer Caswell over POR, as too many folks have reported the POR product peeling (something to do with Ethanol fuel I think).

Amazon.com: Caswell Epoxy Gas Tank Sealer Motorcycle Kit (Burst Pack Format): Automotive

You might need two kits to treat a tank your size.
 

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WD40 after etch?

I understand the application of WD40 after etching is intended to prevent the immediate attack of corrosion on the unprotected surfaces, but doesn't it also risk the provision of a clean substrate for the subsequently applied sealer to adhere to?
 

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I understand the application of WD40 after etching is intended to prevent the immediate attack of corrosion on the unprotected surfaces, but doesn't it also risk the provision of a clean substrate for the subsequently applied sealer to adhere to?
I suppose it could, but the sealer kits typically include instructions for prep, if not an actual prep/cleanser solution. So, naturally, those should fold into the process.

I use the WD40 after the rinse to displace any lingering water. If the sealer does not have any prep guidelines, you might still flush the tank with denatured alcohol or acetone to clear out any petroleum residue from the WD40 that might interfere with the sealant. Either of those should dry out quickly (within an hour) to leave a good surface.

I would not, however, rely solely on the phosphoric acid residue to guard against rust for more than maybe an hour.
 
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