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Best way to remove old fuel from tanks

Old 03-19-2020, 02:49 PM
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Default Best way to remove old fuel from tanks

Title pretty much sums it up however fuel has been in tanks for over 4/5 plus years and just looking best method. Probably about 40 gallons in each tank. Also any cleaning agent available to use during/after the process after draining. I have a couple used 12 volt electric fuel pumps that are in working order that I have no use for as I am running mechanical. I will have plenty of filters I plan to swap out during first few runs on fresh rebuilds.

I realize this may take some time to get all the old fuel ETC out. I would imagine their is some water, gummy sludge, varnish and so on in them. I'd like to take a peak with bore scope after draining/pumping.

Last edited by getrdunn; 03-19-2020 at 02:59 PM.
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Old 03-19-2020, 03:27 PM
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Also is there a good proven product I can add to tanks and let sit for a day or so before pumping out? Just trying to break down the poop before pumping. And repeat process with 5-10 gallons of fresh fuel each. Seems like I used a BG product for injector cleaner years ago but this is a little different.

tks
John
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Old 03-19-2020, 04:22 PM
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E85 would probably do a nice job breaking down the sludge and varnish.
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Old 03-19-2020, 05:19 PM
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Assuming boat is on a trailer.
Remove fuel sender and pump what ever you can get out. Use a power washer and blast the inside, and if you can use heated water. Can now pump it out with larger pump or shopvac. Do this several times till it looks clean. If it needs some more, dump some acetone in and get something to rock the boat. Tie line on a cleat and yank with something
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Old 03-19-2020, 07:35 PM
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I would probably try to drain all of the old gas, fill with water and drain again. Then get a couple/few 5 gallon buckets of purple power cleaner/degreaser, put as much as you can afford to in the tanks and pull the boat around to slosh it. Maybe then run some heet for the first couple tanks and obviously a few filter changes.
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Old 03-19-2020, 10:30 PM
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It depends on WHAT was in it when it was stored.
If it was "ETHANOL ENRICHED" gasoline, you should expect it to be nasty. If it was STRAIGHT GASOLINE, you will be in better shape. If you added Sta-bil to whatever was in it, you can plan on running it in your lawnmower - boat will probably run ok on it if you arent supercharged and just cruise easily.

Step 1 - pull the fuel filter/water separator. Dump it into.a clean glass jar. Smell it. It will either look/smell decent ish or it will smell like turpentine. If it looks and smells ok, then you may want to plan on keeping what you pump out.
Step 2 - pump it out. I would just tap into the regular fuel line to the motor, and use the in-tank pickup. Take one of the electric fuel pumps, hook up a 15 to 20' long "lamp cord" style wire to the pump. Use very well crimped or soldered wire ends and securely attach to the pump terminals. Under NO circumstances should you allow any chance of spark near the pump itself. Use an EXTERNAL battery, outside of the boat, and rig a switch in the wire for the pump. No loose or spark happy connections. Get your wiring figured out first, put a long enough discharge hose on the pump to whatever you are gonna pump the fuel into. Use clamps on all hoses. Then pump the tanks dry. Leave the pump hooked up to the last tank, but plug the discharge end with a dowel, etc (tighten the clamp).
step 3 - if the fuel that came out looked and smelled ok, then I would refill to 1/4 tank with E10 gas and add Sta-bil stabilizer to it. If the boat is on a trailer, go drive around the neighborhood zigzag, sloshing fuel all around in the tanks. Swerve, speed up, hit the brakes, have fun.
Step 4 - install your old filter/separators. Connect the electric pump to the feed line on your engine filter. Run the pump to fill the carb bowl. Watch the bowl events to make sure the float doesnt let it keep flowing after it is full (if your electric pump is less than 8psi, you should have no float leakage). Once the carb is full, a shot of starting fluid and you should be running (I usually remove the belt to the raw pump when starting one that's been out of service for a while - and might as well plan on an impeller as well, but not to worry about til you've got it where it starts and runs). Make sure you have oil pressure when cranking. Don't run the motor more than 20 seconds.
step 5 - replace impeller and hook water to the motor with muffs. If the old impeller was intact, great. If it wasnt intact, you need to back flush everything (trans cooler, oil cooler, ps cooler, etc) to blow out any pieces that went upstream and got trapped.
step 6 - with water to the motor, restart it. Watch oil pressure, blip it a few times, settle in at 1,800 - 2,200 rpm. Make sure water is co.ing out both exhausts about the same. Let her run long enough to get 160 on the water temp (assuming you are running a thermostat). If. At any time during this, it starts running badly or stumbles, turn it off and dump the filter/separator. If you do make it up to temp, shut it down, let it cool, then dump the filter/separator into your glass jug again and let it stand. Swap to a new filter.
step 7 - move the pimp to the other tank and engine. Repeat above steps again.

Couple of months ago, I brought an old Mastercraft (Pleasurecraft, 351 Ford) back to life after 6 years sitting up. It was stored w Sta-bil in it and the fuel was so good, he ended up cruising the lake to run it dry (with a buddy on a jetski along to tow him if it went sideways).

I put plugs in it, new filter, impeller, flushed the trans cooler for the velvet drive, changed the oil, and tightened some connections. Fresh battery and good to go.

Fingers crossed that your tanks arent as bad as you think.
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Old 03-19-2020, 10:40 PM
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I recommend the liberal use of high explosives, will clear out the old fuel.and vapors as well as any residue, all in short order.
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Old 03-20-2020, 07:36 AM
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I had to pump about 70 gallons out of my first TG, sucked it out through the fill tube and put it in one of those square plastic containers, it was kind a brown in color, but ran good in the lawn mower and John Deere.............
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Old 03-20-2020, 12:54 PM
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Thank you for the recommendations. Boat sits on a trailer minus engines currently. Previous owner of boat suspected water in tank/tanks after fueling up and smoking a new rebuild. Boat had sat for sometime prior to him purchasing. Think Iíll use a clear hose to pump it out also just to see the consistency and have the bow up as high as I can get it. I kinda figured pumping through the sender or fill. I wasnít certain if there was any kind of screen on the pick up in tank or not and didnít wanna plug that up with crap if and not sure where itís at in the tank. I remember running out of fuel on a 42 with trip scís and it took like 20 gallons to get it up and running again on the water. Kinda gave me an indication the pick ups werenít in the very rear.
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Old 03-20-2020, 01:14 PM
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Siphon it out, get the siphon started by blowing a vac into the vent hole for a moment, works great.
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