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old gas in vehicle

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Dec 11, 2012, 9:13 PM

Post #1 of 4 (1047 views)
old gas in vehicle Sign In

I have a 99 Chevy Silverado LS 2500 4x4 with a vortec 6000 engine and it has been sitting in my drive way for 3 Yrs now. The fuel smells bad. It has about a quarter of a tank of fuel. I have not tried to start it. It has 160,000 mi. It would be great if I could get some information on the best way to drain and flush the system without doing damage to any of the components. I know that replacing some of these may not be avoidable. If you have the time and can respond to this message it would be very helpful. Thank you for your time.

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 12, 2012, 12:40 AM

Post #2 of 4 (1000 views)
Re: old gas in vehicle Sign In

DON'T START IT YET! Isn't easy to know what the heck has happened to the fuel in 3 years. It's not good at best. So many formulations there's almost no way to know but trust me it's not pure gasoline - just try to find that word at a gas station!

Drain every bit you can now at least and look at some in a clear glass. It's probably at least dark with the stink you mentioned. If it's getting like any kind of salad dressing this should be all flushed out and NOT run thru the system yet. Report back but you can go ahead and tend to the battery - forget old one now and go only for new unless it was on a maintainer and new 3 years ago. Any funky features or alarms will lose or have lost memory. Don't expect it when all ready for it to plain run fine for a while no matter what.

A or B. If it doubt send this out for total cleaning out. If you want or think you can give it a go do put some solvent in it now. Careful - lots of bullcrap out there that can make things worse. SeaFoam products so far have been great - read which for which. Chevron's Techron is good. Not as many choices here but Stabil by brand does market fuel treatment for storage and some claims of reversing effects of ethanol that I'm not to sure of. Hey - items get stored seasonally all the time but not usually for three years and with fuel.

There's a procedure called "Motor Vac" that forces strong solvents thru injection items. I don't own one but those who do say they rock for cleaning injection/fuel delivery items. There's always a limit to magic anything.

Buy two fuel filters as they first new one can't be trusted for long. Lube and rustproof or put something on those flare nut fittings as those down on frame rail suk and can snap right off or twist up lines needing a kit in no time if not dealt with.

You could be ok to run it but what you do now will matter. Don't trust brakes, change oil, re-grease and any services. I should talk - check spare tire once every ten years too!

Outdoor storage usually comes with a price. You can get thru it and minimize the surprises. Good luck,


PS: Second fuel filter is for soon after you have it going and run for some time just toss it again. Cheap prevention.

(This post was edited by Tom Greenleaf on Dec 12, 2012, 12:42 AM)

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nickwarner profile image

Dec 12, 2012, 4:40 AM

Post #3 of 4 (983 views)
Re: old gas in vehicle Sign In

I'd take off the fuel tank and toss all the gas in there. If the strainer sock looks contaminated on the fuel pump toss that for new one. Look inside with a light and see if the tank has any sludgy residue. If it does it will need a good steam cleaning. Like Tom said, fuel filter must go. Your lines and fuel rail have this old crap in it, so when you put it all back together leave the return line at the tank unhooked. Put your fresh gas in the tank and jump the fuel pump relay until fresh gas is coming out of that return line. Then proceed with the rest of the checklist for a vehicle left sitting three years. Be on the lookout for rodent damage. Physically take your entire air ducting apart to look for nests. Suck one down an intake and bad things happen. Get a good look at your brakes. Rotors will certainly be rusty and will feel/ sound crazy when you first drive it. Before you try to move it be sure the brakes have a good firm hold. Moving is optional, stopping isn't. Tires, rubber hoses and such may have some dry rot issues along with gaskets and seals which will begin showing themselves when you start putting mileage on it. I'd pull the blower motor down too to look for nests. Been in plenty of cars when I hit the fan switch and got peppered in the face with mouse nest coming from the vents. Seen one or two cars where the nest caused a fire in the heater box.

MarineGrunt profile image

Dec 12, 2012, 8:08 AM

Post #4 of 4 (964 views)
Re: old gas in vehicle Sign In

Speaking of mouse nests I had one get into the wife's minivan last year and that's when the vehicle was an everyday driver. It chewed up the wire that runs to the fuse block that controls the hvac so can only imagine what they might've done if it wouldn't have been driven for awhile. I still have to trace down that wire and fix it correctly. I found the nest. It was inside the cabin air filter that's located behind the glove box. I could be wrong but I believe some GM trucks have the in cabin air filters so that may be a good place to check too.

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