: Defuel 1993 Allante?

Mike from Cle
01-16-12, 12:33 PM
Does anyone know how to defuel all of the gasoline from a 1993 Allante gas tank?

01-16-12, 03:35 PM
Have you tried siphoning the gas out?

Mike from Cle
01-16-12, 07:52 PM
Something (anti siphoning barrier) is blocking the hose from entering the gasoline tank.

D Yaros
01-21-12, 11:20 AM
Isn't there a drain plug in the tank?

01-21-12, 11:29 AM
there's probably a roll-over valve that prevents fuel leaking out if the car flips over in a crash ... also prevents siphoning ... there might be a trick if you pour gas in while trying to stick you siphon in there ...

other than that you'll have to drop the tank down - i don't think there's a drain plug ... but i've been wrong before

01-25-12, 08:20 PM
Is the tank being replaced?

Mike from Cle
02-04-12, 01:15 PM
The gas tank is not being replaced. The Allante has been sitting in the outdoors and recently in a garage for the last four years, no road driving. I would start the Allante now and than but the engine is really being to miss and the engine is running at high idle. The gasoline has been sitting in the tank for years, that can't be good. I added Seafoam to help but the engine stills idles high and the timing is missing. The engine tries to slow the idle than beings to miss fire at low idle which is causing the engine to increase the idle. So I thought to start with the simple items removng the old gasoline replacing it with fresh gasoline. Another issue I am expriencing is when the engine is turned off but the ignition is still on, I can hear an electric motor clicking noise coming from the TBI, sounds like electrical motor gear is trying to turn and the gear is slipping. Not sure if it is related to the high idle issue.

02-08-12, 01:13 AM
Seafoam (and any other snake oil) is a nono. It's basically paint thinner. Ok for cleaning parts, not for running through an engine.

The idle problem sounds (at least partially) like a faulty ISC (Idle Speed Control) motor (that's the electric motor sound you're hearing as well). As for the missing, I'd start by replacing the plugs and wires, they're ancient if original, and sitting so long probably didn't help any.

There is a "sticky" thread at the top of the Seville/Eldorado and FWD Deville/Fleetwood forums, with instructions on how to pull codes using the HVAC or DIC controls. I'm not sure if the Allante had this functionality, but give it a try. If not, do you have access to a scan tool?

03-19-12, 01:26 AM
You can disconnect the filler valve from the Rubber Hose that goes into the tank. Then you will be able to insert a syphon hose into the rubber filler hose, bypassing the filler neck that has the anti-syphon piece.

But you should be able to put a piece of 3/8" hose through the filler neck with a little coaxing.

04-25-12, 12:34 PM
Just did this yesterday to my '90 thats been sitting for 3 years. Here's how:
At the PS bulkhead harness connector find the grey wire with a light green spade socket.
This is the injection primer connection: 12 volts applied to this connector will engage the
gas tank's fuel pump. To drain the tank, disconnect the engine side of the fuel filter (under the car) and attach
a threaded-to-hose fitting to the fuel filter. Attach a 4' fuel hose to the hose end of this fitting, with the other end
in a suitable gas container of course. Now apply 12 volts to the primer disconnect and drain away.

Mike from Cle
03-25-15, 07:26 PM
Ok, I found and disconnected the fuel filter. Question, which PS bulkhead harness connector? I found two bulkhead wire connectors located inside the engine compartment firewall, passenger side. Looking from the front of the Cadillac into the engine compartment, is it the left or right bulkhead connector. Sorry I am don't know what a PS bulkhead harness connector is or which one it is.

03-26-15, 11:27 AM
I agree you have a bad isc motor the missing could be ignition related or you may have an injector issue running the stale gas through them.If you have the service manual look up how to display the fault codes through the dic.there is also an override that enables you to disable the injectors 1 at a time to pinpoint the cyl not firing.
if you need someone to walk you through the process give me a call.Ross 570-281-9614
eastern time best time to catch me is the evenings 4-10 pm