So I've been battling hesitation issues with my 3.1 swap for way too long. After tons of replacing, rechecking, rewiring, its still there. So my last stop was the gask tank. I dropped it out of the car tonight, to find something quite interesting. A few months back my town changed to 10% ethanol gasoline, so there was no avoiding it. I changed my fuel filter at the beginning of the summer, only to see dark, nasty gas coming out of it. Since I'd never changed the filter, I figured it was normal. After inspecting my tank tonight, I found that there was a lot of loose rust particles floating in the gas. The fuel pump sock was dark brown, and my new fuel filter also had rusty gas in it. My dad mentioned that ethanol cleans the rust off the sides of the tank, thus why I've been getting all this rusty gas. I have a few pictures for you all, so you can see just how this ethanol is knocking all the rust in my tank loose. I'm going to wash the tank out with muratic acid, as this really cleans rust great. After reading about it, I cleaned out my 79 Kawasaki KZ1000s gas tank with excellent results. As soon as I am done, I will post more pictures for everyone to see. Since ethanol is popping up more and more in every town, I figured a lot of us Fiero owners are going to encounter this problem.

My tank was full of that crud long before ethanol came to town. My solution was to replace the tank.

I've washed it out a few times with muratic acid, heres a few pics:
Just a small fraction of the stuff I filtered from the gas.


In the middle of an acid bath




After a rinse




Still lots of junk floating around. Now I just have to wash the tank out 400 times, then coat it with WD40 and I should be good to go!

Thanks for the advice, my town doesn't have that gas yet. But I can expect it in about a year or so.

quote Originally posted by toadson: My dad mentioned that ethanol cleans the rust off the sides of the tank, thus why I've been getting all this rusty gas.

The car is 20+ years old without constant driving. Water in the fuel has corroded the tank. Ethanol absorbs water. It's going to do nothing but add to the proplem without proper care. Adding Marvin's Mystery Oil has been suggested to help keep things rust free. Keep the tank as full as possible helps too.

Perhaps we should compile a listing of gasoline made with and without ethanol. The Enthanol will absorb water but it is then run to the engine and burned out.

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

Wow!!!

Whats your receip with muriatic acid? quantity, mixing (with water?), how much time you let the acid stuff in the tank?

quote Originally posted by Gokart Mozart: The car is 20+ years old without constant driving. Water in the fuel has corroded the tank. Ethanol absorbs water. It's going to do nothing but add to the proplem without proper care. Adding Marvin's Mystery Oil has been suggested to help keep things rust free. Keep the tank as full as possible helps too.

I have an 86 GT in the garage I don't anticipate driving too soon. I have added Sta-bil to a couple gallons gas, added that and ran the (knocking) motor until it warmed up, then added a couple more gallons of gas laced with some DryGas, ran it, a couple more with a heavy mix of Marbel Mystery oil, ran it, and a little more with some more Sta-bil. The fuel gauge pointer fell off before I got the car. I run once a month or so, but my intent is to keep the gas from turning to crap. I understand the pickup tube in the tank can split if it is allowed to drive.
<edit> er, dry. I can totally see the need to wash out the innards after seeing this post. If and when I do an engine swap I suppose this will be on the 'To-Do' list.


Nice post with Pics!
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John DuRette
Custom 85 SE/86 GT
"Kinda makes you nostalgic for a Members Only jacket"

[This message has been edited by USFiero (edited 10-07-2007).]

good info. and thanks.

The thing to remember is that here in Canada, it is pretty common to add gas line anti-freeze (methol Hydrate) to take any water out of the gas. We have sold Ethanol gas for the last 30 or 40 years and the tanks like it.

If you are in a climate that temperatures vary alot, a steel tank will sweat. If it is full most of the time it doesn't get a chance to sweat, but a partly full tank will certainly sweat because of the damp air coming in the vent. There is your rust source.

Once the tank is clean, ethanol all the time is a good idea to keep it clean, and keeping a full tank is another good idea.

Thanks for the educational pics. I hope this thread helps some other guys.

Arn

I just poured the acid in there full strength, washed it around as best I could, then let it sit for maybe 10 minutes. If anyone tries using this stuff, it is important that you do it outside, and that you wear gloves, a respirator, and goggles. You do NOT want to breathe the fumes from this stuff. You can water it down if you like, but its all personal preference. Theres a lot of stuff on the internet about it, so you can google it too if you want. After you use the acid though, you need to flush it out with water many, many times. Once you think you have it clean, take some WD40 to the tank, to dry up any water left inside. Then rinse it out with a litttle bit of gas, and let it air dry. You should be good to go after that.

Just a suggestion.

I'd use Methohydrate instead of WD40. It will chemically absorb any moisture and if there is residue, the engine will eat it up.

Arn

I got the tank back in the car, and all I can say is WOOOOOOOOOOOOHOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!! My hesitation is gone! Gone! GONE! I can bark the tires once again! My fuel pressure has increased by about 4 PSI, and I am VERY happy. I've been battling this hesitation issue for months, and I was about to give up. Just a short summary.... When I swapped the 3.1 in last winter, it idled rough for a few months. An EGR solenoid was stuck open, and one day I started the thing up, and it sounded completely different. Im not sure why the valve was stuck, but it decided to free itself and I was happy to have the car running right. At full throttle, I could bark the tires shifting into 2nd without even trying. The car ran this way for a few weeks, and my town switched to the ethanol gas around the same time. I noticed my car couldnt really bark the tires like it used to, but I didnt think much of it. It eventually got to where it couldnt bark them at all, and this hesitation started to develop. I scanned numerous times, replaced many sensors, among other things, and nothing seemed to help. Now that the gas tank is clean, and I have a new pump strainer and fuel filter, the car runs great. I barked the tires without trying (again, it never had the power to do this most of the summer), the car doesnt want to die shifting into 2nd,and it is actually responsive to the throttle. All I know is Im cleaning the gas tank on my 88 project car before I ever run it. I cannot believe how much of a difference this made. For once, I can enjoy driving my Fiero!

Heres some pics of the final product. You can see some light surface rust already starting to form:







Wish I could get some better pics, but the camera didnt fit in the tank.

[This message has been edited by toadson (edited 10-07-2007).]

Common problem with GM tanks for that era. It's not the alcohol.

JC Whitney sells a sealant that works nicely. You have to remove the tank and get that stuff out of there and then pour in the sealant, roll it around and let it dry.

I dont think there is a station around here that doesnt have it. I started watching years ago and at one point no one had 'real' gas anymore.

Wisconsin has been using 10% for years, I wonder how bad all my GM tanks are.

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PROJECT 1986 GT Stormbringer

I'm not saying the ethanol caused the rust, I'm saying that it has been slowly cleaning the rust off the sides of my tank, thus letting it get sucked up by the fuel pump. My dad is a farmer, and he has been using the new soy diesel fuel that does the same thing as the ethanol gas. Its been cleaning the inside of the tank, and clogging fuel filters. He's been changing the filters quite often because of this.

Another test I did after installing the clean tank, was to release the pressure at the schrader valve. Before the cleaning, I would let the pump prime, then press on the valve, and gas would just trickle out. Now when I press the valve, it shoots up over a foot high.... so yeah, this helped tremendously. I still can't believe it.

If you use Muriatic acid, make sure you use it full strength. If you cut it with water it will deactivate the acid. Definitely make sure you wear gloves and wear a respirator. That stuff will burn your skin and your lungs. I plan on doing this to mine as well, however I don't think I would let it sit in my tank that long. Muriatic acid will attack the rust on contact, however the fumes will cause corrosion. Go figure . The best way to do it is to dump a pint or so into the tank seal up all ports with plastic wrap and just swish it around the tank for about thirty seconds or so. Then you will want to immediately add water to deactivate the acid. I would then dump acetone into the tank and swish it around and then use something similar to this stuff to seal the tank and prevent any rust from forming in the future, however it says you can apply it over rust. But I would feel better if the rust was gone.

Ya ethanol is the devil for older cars. But where I am I can't find a pump without 10%, most pumps don't even tell ya.

I can buy e85 at more than half the stations by my house. Have not seen "real gas" really ever sence I have started driving 6 years ago.

Out here in the west, all gas has 10% ethanol for at least 6 months of the year (fall, winter, early spring.) It is "oxygenate gas" and is supposed to help cut smog (and ozone formation) in cooler months of the year.

For cleaning steel, phosphoric acid works better than muriatic (which is diluted HCl.) Diluting muriatic with water doesn't deactivate it, it just makes the concentration weaker. Phosphoric acid (available from ag. supply stores as 'milkstone remover') cleans the rust off and pickles the steel with phosphate which inhibits new rust formation til you can get some sort of sealer on the metal--I've used a product that can you can probably get through a radiator shop that you slosh around in the tank and then let dry in the warm sun. Dries hard to the touch and doesn't tend to peel like Kreem.

Steel cleaned with muriatic acid, btw, seems to begin to form new rust immediately. Phosphoric acid is the active ingredient in "Naval Jelly."

Probably not a bad idea to run Techron through the tank 3 or 4 times a year. It cleans, and helps remove moisture. Keeps the fuel level sender working properly, too.

[This message has been edited by Brian Lamberts (edited 10-10-2007).]

I should have updated this a few days ago. My hesitation has come back, and fuel pressure has dropped once again. I removed the fuel filter, only to find more rusty colored gas, along with rust particles. I flushed the lines again, only to find more rust particles. I'm suprised at some of the stuff that has made it past the fuel pump sock, but I'm thinking about dropping the tank again and just replacing the pump. I'm not sure if the pump is just junk, or if there is that much more crud clogging things up. I'll probably just order a Walbro so I can make this thing driveable.

i was afraid that my tank lookt the same.. but i when i chek´t it, it was like new inside.. and its the original from 86.

quote Originally posted by toadson: I should have updated this a few days ago. My hesitation has come back, and fuel pressure has dropped once again. I removed the fuel filter, only to find more rusty colored gas, along with rust particles. I flushed the lines again, only to find more rust particles. I'm suprised at some of the stuff that has made it past the fuel pump sock, but I'm thinking about dropping the tank again and just replacing the pump. I'm not sure if the pump is just junk, or if there is that much more crud clogging things up. I'll probably just order a Walbro so I can make this thing driveable.

Don't they make replacement tanks? Might be worth fabbing one.

quote Originally posted by Brian Lamberts: For cleaning steel, phosphoric acid works

Which would be why using coke/pepsi works.. scary huh?
oh, and its not the the ethanol that does that... but I wouldnt use it anyway, you pay a little less, and use more gas...

[This message has been edited by AJ7 (edited 10-17-2007).]

quote Originally posted by jscott1: My tank was full of that crud long before ethanol came to town. My solution was to replace the tank.

Who sells new tanks?