I finally got the gas siphoned out of the fuel tank and got it removed. Now I’m hoping for someone’s opinion on some issues I ran into.

Q#1: After flushing it out, I noticed part of the baffle is cracked in a couple places (shown in pics). Is it too badly cracked to allow the gas to flow correctly? If so, is there any way at all to get this repaired with some kind of sealant so it can function properly?




Q#2: I’ve flushed the tank out 3 or 4 times, removing some milky-colored reside of corrosion (filled it w/ water, swished it around emptied, repeated). There is still corrosion stuck to the insides. Would it be a good idea to pour vinegar for a day or so to remove the rest of it? You can see part of it in the 1st photo.


Q#3: I was planning on smoothing out the rusted areas around the welded seam, and a few other places, then apply a coat of primer along with a top coat. Anyone recommend spray Rustoleum or Krylon?

Q#4: Lastly, I’ll be replacing the fuel pump for sure, but not quite sure about the sending unit itself. It does have a little powdery corrosion in some areas. Would it be worth trying to soak it in vinegar to see if I can get it going again, or best just to get one at the fiero store?



I appreciate someone’s time giving their opinions.

1. Baffle is fine, as long as it doesn't interfere with fuel level float.

2. Rinse it again with water.

3. Duplicolor primer and truck bed liner for topcoat.

4. If the sender works, reuse it after calibrating it (0 Ω empty, 90 Ω full)

There is a product called Evap-O-Rust that will remove rust from the inside of the tank. I've gotten it at Tractor Supply - about $22 per gallon but can be reused several times. It is not an acid. It is a chelating agent that will tie up the iron oxide as a soluble organo-metallic compound. Works amazingly on rusted tools

If the sending unit does not pass the ohm meter test, tabs can be pried to get to the inside. There is fine wire wrapped around a curved bar. This can be lightly sanded with 1000 grit sandpaper to renew the corroded surface

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formerly known as sanderson
1984 Quad 4
1886 SE 2.8L
1988 4.9L Cadillac
1988 3800 Supercharged

Check new F-pump directions etc.
Many new pumps Do Not use the pulsator above the pump. Others do and likely need a new one of that.

Many new pumps have a new plug to attach to wiring. Make sure the splice for + can't touch any metal even if have insulation on it. Insulation may "rot" over time flooded w/ gas and gas w/ ethanol.

Gauge sender often reads near 0Ω empty and a bit > 90Ω when tested on a "bench." Is not made to really accurate.
Sender may have a small spring inside. If sender taken apart watch for this because lost spring will be a problem.
Spring keeps the rod part "tight" to body to get a good ground.
Even then testing on a bench can cause fake results as you move the arm up/down by hand.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Thanks everyone --- What I'll do then is flush the tank out good with Evaporust or some other corrosion remover and flush it out a few more times. With the sending unit itself I'll open it up and clean the wire around the curved bar.

As for testing the unit's ohms reading, where on the unit would the multimeter leads be connected?

For the fuel pump, I noticed the rubber sleeve that surrounds it. Would it matter if I got a new one that doesn't have this? I've noticed many new ones do not...
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[This message has been edited by Brent7088 (edited 07-06-2022).]

The pink and black wire for testing the sender

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formerly known as sanderson
1984 Quad 4
1886 SE 2.8L
1988 4.9L Cadillac
1988 3800 Supercharged

Is likely for noise reduction. Sim to the pulsator that stops "pipe hammering" that can also break fuel system parts.

Fuel flowing thru the pump is coolant and lube for it. Rubber on outside doesn't matter for that.