I have a question on the best way to drain the gas tank on a 1992 Bonneville SE.

Quick backstory. I just recieved this car from my grandmother who quit driving it a little over a year ago. The problem is, it hasn't been driven at all in that time. It has sat in her carport with what I guess is about 15 or 16 gallons of gas in the tank (gas gauge reads between 3/4 and 4/4). I'm pretty sure since it sat that long the the fuel is no longer usable, so I intend to drain it. However I'm at an impasse.

I tried to go the siphoning route, but found that the tank has the anti-siphon screen on it. The problem now is, I haven't been able to put my hands on a reliable source on how to drain out the gas otherwise.

Any ideas would be of great help.

Thanks.

There is no real easy way to get into the tank without dropping it. Some have cut access holes under the rear seat when doing fuel pumps to avoid dropping it, but that requires a welder to finish.

if dropping it isn't an option, you might be able to get away with some octane boost to get the octaine level back up and then run the gas out of it, followed up by some injector cleaner. in the next tank.

I'm not 100% sure, but i don't think gas would go that bad over the course of a year. Someone else might be able to chime in and verify this.

Well, to update a bit, I decided to go the, just start it and see if it blows up route.

I'm happy to report that it did not. I put some fuel drier and octane booster in the tank before I started it and turned over relatively easy. I did have quite a bit of white smoke from the tail pipe and from the joint between the exhaust headers and the down pipe to the cat, but that cleared off after about 10 minutes of running. There was also a heavy bit of fumes also, but I'm attributing that to debris and such that have been sitting there (I did brush off the engine and such before I tried to start it). I drove about 25 miles on the property (I made a lot of circles), and nothing seriously wrong cropped up. Tomorrow I'll take it out on the road since I got a tag for it, and see if I can drive off the rest of the tank.

I'll let you guys know how it goes. I'm really impressed with, and glad to have found this forum. It'* a great source of information.

Update:

Well yesterday I took it out on the road, and drove around for about 2 and a half hours. Didn't make much of a dent in the gas tank, but came across a new problem. Stopped to get something to drink, and when I got back out to the car, it would turn over, but not start. I tried it a time or two, let it cool, checked fluids and fuses and anything else I could think of easily done. Tried to start again, and the same problem. I got desperate and pulled out the battery booster I brought along, just in case, and hooked it up. Started right up.

So I took it home, let it cool off again, and pulled the alternator, and battery out and took them up to Autozone and had them tested. Both good. The people there said that it'* most likely the Cam and/or crankshaft position sensor. I looked around the forums and saw a few topics on this, but my problem isn't "quite" the same. Though I am getting a slightly rough idle after it'* been driven awhile.

I suppose the next step is to get those items and swap em out. After looking at the procedure, I'm wondering if I should go ahead and replace the Crankshaft oil seal. I probably will since I'll be right there anyways.

Anyways, wish me luck.

(btw, in case anyone does have an idea. It'* a 92 SE, no mods)

Another update:

Today I replaced the Camshaft Position Sensor, since it was the quick and easy one to do, hoping I'd get lucky. So far it seems that was the trick, idle back a bit smoother, and after doing many stop/starts and putting another 75 miles on it, no major problems to report. I did notice at idle after it had a chance to get warm, the amp gauge was bouncing a bit, but only between about 12 and 14 amps. Not sure if that'* something to be concerned about, but it didn't present any issues.

I hope to get the rest of the tank run off tomorrow, then I'll feel confident enough to spend the money to do a complete tune up. I will say I'm getting much better gas milage than I thought I would get, unless my gas gauge is off. :P I suppose that'* a benefit of it being driven by my grandmother and only having 85k miles on the clock.

Anyways, will update again soon.

glad to hear things are going well. Let us know if you need anything else, and we'll wait to hear your updates after your new tank.

These engines have been known to get pretty good gas mileage if you take care of them. I would see 24-26 normally in my 93 SSE, and 29 on the highway, and my 93 SSEi gets 22-26 city/highway. The L36 in the 95+ SE/SSE has been known to get up to 33ish, while the L67 in 96+ is capable of up to 30 if you are light-footed (not many are)

Well I got a bit more gas run off today, down close to a quarter, but there is a downside. The cranking but not starting came back today. Only happened once, but luckily I was already back at home when it did that. After driving for awhile, I parked, ran inside to grab my phone charger, and it did it. I just got back after running a few errands with the Vibe, tried to start her, and she cranked right up. So from looking at other people'* threads, it looks like I didn't get away so easily. I'll have to swap out the crank position sensor. I'll probably get to that early next week, and let you guys know how it goes.