PFF - Pennock's Fiero Forum, PDA Edition

Easy way to drain the gas tank? (Page 1/3)

Dennis LaGrua

JUL 17, 07:40 PM

I have a Fiero that has gasoline in the tank thats about 2 years old. It is still liquid and can flow ok but I want to find an easy way to drain the tank and put in fresh gas. My idea is to attach a drain hose to the fuel feed line, turn on the key to start a siphon and allow the tank to drain into a can below the tank level. Its in a Fiero with an engine swap so I don't believe that energizing from the ALDL plug can help. Will this siphon method work? I believe it will but not sure.

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Patrick

JUL 17, 07:53 PM

quote

Originally posted by Dennis LaGrua:

turn on the key to start a siphon...

You lost me there.

Is the fuel pump connected to the harness? If so, why won't supplying 12v to the pertinent ALDL terminal work?

[This message has been edited by Patrick (edited 07-17-2023).]

theogre

JUL 17, 10:56 PM

He likely doesn't want "bad gas" or "water" going thru the pump.

Separate the return line rubber at the tank and suck out there. ⚠️ If not careful will auto siphon as soon as rubber is off of either hard line section.
Return line in the tank reaches bottom same as the pump.

Fiero tank is too hard to steal gas on the street even w/ that info.

Won't get last ~ 1 gallon either way to drain.

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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

[This message has been edited by theogre (edited 07-17-2023).]

RichLo1

JUL 18, 12:15 AM

If its actually 2 year old gas, just add a few gallons of fresh stuff and run. If its significantly older than that then be honest.

Patrick

JUL 18, 01:08 AM

quote

Originally posted by RichLo1:

If its actually 2 year old gas, just add a few gallons of fresh stuff and run.

It might make a difference how much ethanol is in the gas. I've added fresh gas to eight year old gas (that had no ethanol), and it was fine.

theogre

JUL 18, 06:32 PM

quote

Originally posted by RichLo1:
If its actually 2 year old gas, just add a few gallons of fresh stuff and run. If its significantly older than that then be honest.

quote

Originally posted by Patrick:
It might make a difference how much ethanol is in the gas. I've added fresh gas to eight year old gas (that had no ethanol), and it was fine.

I've said ~ same thing but many still want to dump all old gas even before Ethanol.

big issue is Ethanol pulls water from air and worse if cap is bad/loose or have other problems letting air into the tank. worse if has a lot of E10 so has more Ethanol then that pulls more water then that mix sink to bottom.

is often not a problem to most cars because often don't have full tanks but for SUV etc big tanks can have more problems even 1/2 tank or less.
Don't confuse w/ small motor things or Marine use w/ Vented Caps and other design issues and huge amount moisture/water to deal with.
Example: many small motors simple have a hole at bottom of gas tank or small filter/weight that can suck a tank dry and any water then get to the carb fast.

[This message has been edited by theogre (edited 07-18-2023).]

Dennis LaGrua

JUL 19, 02:53 AM

quote

Originally posted by Patrick:

You lost me there.

Is the fuel pump connected to the harness? If so, why won't supplying 12v to the pertinent ALDL terminal work?

Yes have an ALDL terminal but the engine is a 93 Cadillac Deville with a different ECM. Not sure if that pin is on that ALDL connector. Will check it out.

Patrick

JUL 19, 03:01 AM

quote

Originally posted by Dennis LaGrua:

Yes have an ALDL terminal but the engine is a 93 Cadillac Deville with a different ECM. Not sure if that pin is on that ALDL connector.

Oh right, I wasn't cluing in to the different engine having a different ECU, having a different ALDL port.

Using the ALDL port is a convenient way to temporarily power a fuel pump... but if you don't have that option, I imagine there must still be a relatively easy way to get power to the fuel pump.

theogre

JUL 19, 08:06 AM

quote

Originally posted by Patrick:
Oh right, I wasn't cluing in to the different engine having a different ECU, having a different ALDL port.

Using the ALDL port is a convenient way to temporarily power a fuel pump... but if you don't have that option, I imagine there must still be a relatively easy way to get power to the fuel pump.

It doesn't matter have Different ECM.
GM has Standard ALDL for all OBD1 vehicles. Only Data Out pin changes for Different Data Speeds/Formats... E for 160 "baud" or M for 8192 "baud"

Think all GM FSMs and a few other Docs list all ALDL Pins but never see a car having all used.

Other Bands have Completely Different "ALDL" w/ way different connector and how it wired and own data format like Ford and Chrysler.
Is Why EPA etc Force all to use same format connector and a lot of "Codes" etc mean same so Feds & States can now just used the ALDL to "test" emissions and Why EPA and others go after "Delete" companies because they make the ECM/PCM to Lie to any Inspector...

css9450

JUL 19, 08:19 AM

I siphoned most of a tank of gas by pressurizing it with my Motive brake pressure bleeder. I had to raise the car, crawl under and remove hoses, run lines in and out and seal them with rags, etc. But I was able to sit there in a lawn chair pumping the ol' Motive bleeder as the gas ran out the hose and into my gas cans.