Good morning. Looking for suggestions on how best to clean out a fuel system in a passenger car. I have a 1999 and a 2001 Buick Park Ave, which both have not run in over five years each. I’m hoping to avoid having to drop the gas tanks to clean them out. Any suggestions on a good way to clean the fuel lines without dropping the tanks? Trying to put as little work into these as I can to ensure they do actually run before putting any real effort into making them reliable vehicles again. Thanks.

Pull the lines off the fuel filter, and cycle the key until the tank is empty. Refill with 5 gallons of good gas, and repeat process. Then, put new fuel filter on it, and 5 gallons of non ethanol gas, and see what you got.

They have in tank pumps so the first thing is to see if the pumps work. Both should have a jumper to run the pumps or you can jump at the relay. Pull the lines and pump fuel like described above. I wouldn't care if the fuel had ethanol or not since you're just flushing with it. Don't be surprised if you end up dropping the tanks for a clogged filter on the pump, a bad pump or bad hoses where the pump attaches to the sending unit.

Thanks. Pretty much what I did with the race car recently. Not so sure about getting the fuel pump on these cars to stay running long enough to flush them like that. I didn't consider running them off a jumper, but will give that a shot. Thanks again.

If there isn't any varnish smell, don't worry about it, just run them.

See if you can find a wiring diagram online for the cars. From memory, not a good one anymore, there should be a fuel pump test lead under the hood. Usually a loose wire with a green connector end on it. Again from memory you can jump to that lead and power the fuel pump continuously. The lead should be near the fuel pump relay under the hood.

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Originally posted by Eman:
See if you can find a wiring diagram online for the cars. From memory, not a good one anymore, there should be a fuel pump test lead under the hood. Usually a loose wire with a green connector end on it. Again from memory you can jump to that lead and power the fuel pump continuously. The lead should be near the fuel pump relay under the hood.

Great info. Thanks. I'll be back at mom n pops house in a few days to give that a shot.