Easy way to drain the gas tank? (Page 2/3)
Vintage-Nut JUL 19, 10:01 AM
Same Title / Different Vehicle

In my experience, vehicles will still run on very old gasoline, IF the fuel is the only issue.

When I needed to remove aged gasoline in the tank of a Chevy; I opened the fuel feed line, installed a ‘T’ fitting to draw-off the fuel and ran the engine as the fuel pump drained the tank….
fierofool JUL 19, 01:29 PM
Attempting a gravity drain by attaching a hose to the feed line at the fuel rail won't work. The fuel pump will prevent the fuel from flowing if not activated. If the car can be put on a lift, detach the rubber line from the metal output line of the fuel sending unit, attach another line into a container, and power the pump through the ALDL. One would need to be vigilant of when the fuel runs out in order to prevent burning out the pump.
Mickey_Moose JUL 19, 01:42 PM

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. Will check it out.




The 4.9l ALDL plug will be wired the same as the Fiero, of course the person that did the wiring could have done some weird **** .
Patrick JUL 19, 04:16 PM

quote
Originally posted by theogre:

It doesn't matter have Different ECM. GM has Standard ALDL for all OBD1 vehicles.



Dennis should be good to go then!
fierofool JUL 19, 06:27 PM

quote
Originally posted by Patrick:

Dennis should be good to go then!



Yes. Scottb's 4.9 Formula had the 93 DeVille ECM and the Fiero ALDL and everything worked just like the Fiero.

Dennis LaGrua JUL 21, 04:28 PM
No fuel pump feed on the ALDL connector here. Must have been omitted by the harness maker. Got underneath disconnected the fuel return line and most of the gas siphoned out into a gas can. Probably got all but the last gallon.
What is used to do to drain the tank is to screw a hose to the Shrader valve fitting on the fuel rail, put the other end in a gas can, then energize the pump at the ALDL connector. That works great but we couldn't do it on this setup.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 07-21-2023).]

Patrick JUL 21, 06:18 PM

quote
Originally posted by Dennis LaGrua:

What is used to do to drain the tank is to screw a hose to the Shrader valve fitting on the fuel rail, put the other end in a gas can, then energize the pump at the ALDL connector.



Aren't you missing a step? ie... removing the valve from the stem?
fierofool JUL 21, 07:12 PM
That's a method that I've never seen suggested before. If the pin is still there in the ALDL, seems like that would be the easiest way.
Dennis LaGrua JUL 21, 08:08 PM

quote
Originally posted by Patrick:

Aren't you missing a step? ie... removing the valve from the stem?



Good question. We are using an old 6' Long R-12 A/C hose. You screw it on and it has the capability of depressing the valve pin. Have done a few this way and it works great but again you need to energize the fuel pump and keep your eye on the flow to see that you don't burn the pump with a dry tank. Draining from below from the return hose isn't hard (if you have a lift) but it leaves about a gallon in there. Anyway job is done . Now we move on to figure out the no start condition. Got the noid lights, fuel pressure gauge, spark tester and multimeter ready but I suspect a dead ECM. We shall see.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

gregr75 JUL 29, 11:55 AM
I was watching this thread with great interest as my car is in pieces and I cannot electrically power the pump…and i am going to drop and refurbish the gas tank. I ended up using a siphon from Harbor freight. One hose end in the large fill port of the tank shoved in as far as possible and the other end into a suitable container.

so far 6 gallons drained

[This message has been edited by gregr75 (edited 07-29-2023).]