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Discussion Starter · #23 ·
Ok. I was able to slide that last tab under the ramp. I used a drift punch to tap it sideways. As it turns out, the ramp notches and fuel pump mounting area are metal. The body of the gas tank is plastic/polyethylene.

Part of that locking ring is still pressed down slightly more than the other part of ring. So I don't know if the gas tank is slightly warped from old age.

Is Surfer's pressure test safe to do? Those cans of compressed air have chemicals. Will it affect any sensors?
 

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Good that you got the ring locked in correct.

Does pressurizing an old plastic tank really sound like a good idea to you?

If I were thinking about this, I would get an old gas cap, modify it to hold a metal tire stem.

And use a bicycle pump to pressurize to about 10 psi.

But no more, because of the plastic tank, might be too flimsy after all these years.

Plastic degrades in UV radiation, and after years of radiation, it will crumble.



ED
 

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Discussion Starter · #25 · (Edited)
They pressurize the tank at the emissions station. I don't know how much
And they actually do use this modified gas cap gadget you speak of.

I need to make a few observations tonight after work. I'll respond again tonight
 

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It really shouldn't be a problem doing a low pressure test. These are made of really tough plastics and even though they don't really see much UV I would bet they are UV stabilized. The problem you are going to have is finding a leak if you have one, especially if it is small.

They pressurize the tank at the emissions station. I don't know how much
And they actually do use this modified gas cap gadget you speak of.

I need to make a few observations tonight after work. I'll respond again tonight
 

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They pressurize the tank at the emissions station. I don't know how much
And they actually do use this modified gas cap gadget you speak of.
They run the test on 76-95 model year systems. Later vehicles have a sensor the monitors the system, throws codes, lights a light.
I can’t speak to how your state tests them. However, if they follow Calif. they use a machine like this for testing.
https://www.esp-global.com/ESS/California/california-evap

They use 1/2 psi (recommended gas nitrogen). The machine measures and calculates the leak rate. To run the leak test, they disconnect the hose at the canister and plug it.

I hope you realize that the system is normally running under engine vacuum. Too much pressure might cause problems of opening a leak where none exists under vacuum.
 

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Discussion Starter · #30 ·
I'm also replacing the segment of evap hose between the charcoal canister and throttle body, because it's so old. But I need to improvise a connector and hose elbow. I was looking for the parts last night. After that, I'll probably take it in for the 2nd inspection.

I was smelling gasoline fumes from the pick-up box area sometimes after exiting truck. Not smelling that anymore. I guess that's a good sign.

I learned from motor vehicle that I can get about two weeks extension on my vehicle tag for less than $5. Also to answer Ron's question, if you fail two inspections they have the discretion to give you a one time pass if you still have not resolved the problem.

(And when this is resolved, I'll contact state officials to get emissions testing abolished)

I'll keep you guys posted.
 

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How would a fuel tank be exposed to UV radiation?
If you bother to look it up, you will discover that it permeates from the sun, and penetrates earth's atmosphere, and you get some even indoors.

Sunlight can be reflected by any pavement, and even dirt.

It is there.


ED
 

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Still don't know why we think the fuel tank is plastic...never seen an OEM tank made of plastic. Have seen them made with a plastic shield underneath, to protect from road debris.
 

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Still don't know why we think the fuel tank is plastic...never seen an OEM tank made of plastic. Have seen them made with a plastic shield underneath, to protect from road debris.
Since the early '70s Ford has used OEM plastic tanks in their vehicles.

ED

Edit: not all Ford vehicle models, but some of them have had plastic tanks.
 

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Discussion Starter · #36 ·
I'll try to get that last section of evap hose replaced tonight after work. What is the best condition for passing the fuel pressure test....full tank of gas..........1/2 Tank.....3/4 tank?
 

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It's actually pretty common these days. My 2009 Tacoma tank is plastic. So is the bed. And neither is degrading due to UV or otherwise. Plastic tanks are superior to metal in many ways, especially when it comes to comes to corrosion. I had to replace the tank on my first car, a used 1966 Mustang, when the top, which was also the trunk floor, rusted through. Lucky that car didn't blow or burn up.

Still don't know why we think the fuel tank is plastic...never seen an OEM tank made of plastic. Have seen them made with a plastic shield underneath, to protect from road debris.
 

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Both of my post-1970s Mustangs had steel tanks. Le shrug.

Raylo32, are you saying the entire bed of your truck is plastic? As in, no steel underneath?
 

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Yes. Toyota calls it a composite bed. It is pretty thick and very tough. It can't be dented and I have never broken or chipped it in any way. The frame rails the bed bolts to are steel, of course.

Both of my post-1970s Mustangs had steel tanks. Le shrug.

Raylo32, are you saying the entire bed of your truck is plastic? As in, no steel underneath?
 

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Old plain-steel tanks will rust quickly from the 10% ethanol gasoline that we more or less have to use now. Ditto steel fuel pumps and lines. Worst are the early mid-80's to 90's fuel injected cars that were not made with ethanol in mind. Plastic or stainless is the way to go.
 
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