Fuel tank clean?

juggaloscorpio · Oct 28, 2016

I am about to replace my fuel pump and sending unit assembly but have a ton of gunk on top of it. I understand that I can just drive the truck to a car was and hit it with the high pressure sprayer but the filler hose is shot and I don't want water in my tank... because of that I have decided to try and clean it off the best I can before pulling the tank itself since it needs to be cleaned out as well from sitting for 2 yrs. Anyone have any suggestions for this process and what type of cleaning agent/detergent/solvent should I use to clean the outside as well as the inside of the tank?

Mark_88 · Oct 28, 2016

Is the bed off your truck? If so, I used a shop vac and a brush (nylon) to loosen the dirt and clean it out of the fuel tank lid. I would not recommend a car wash sprayer or power washer because it can force water into areas that you don't want water.

The area is a prime destination for dirt and road spray so you might also check the frame just under the back of the cab where the wires and fuel lines feed through. I found mine was rusted so badly I couldn't mount the tank strap on the front...this would have required major work to repair or replace so a good thing to inspect...remove the bed and have a good look...and clean, clean, clean...spray it with rust inhibitor once all the stuff is out of the way and you won't regret doing that bit of extra five years down the line.

tomw · Oct 28, 2016

A product I used in the past, Gunk SC, super concentrate, was mixable with kerosene to make larger quantities of cleaning solvent. It might be good for this, or 'stoddard solvent' if it is still available.
Before going through all that, I would try to protect the filler neck where it is cracking, using some plastic bags, such as trash bags, and duct tape. I would remove the bed rather than dropping the tank, and use a garden hose for the most part. A scrub brush and soapy or detergent water would do wonders.
After cleaning, loosen the metal ring retainer, and pull the sender assembly. Get a FLASHLIGHT and look inside the tank, inspecting for sediment & rust. It may not be that dirty to require removal & cleaning.
If it is rusty, you might want to consider total removal, steam cleaning( or hot water at a spray car wash) and then getting it dry for application of an epoxy coating. You can put chain, nuts & bolts, even rocks inside, tape the opening, and then roll it around, tumble, and so on to break loose any surface rust. Once done, it must be coated or it will rust even worse.
tom

juggaloscorpio · Oct 28, 2016

tomw said:
A product I used in the past, Gunk SC, super concentrate, was mixable with kerosene to make larger quantities of cleaning solvent.

I was told from a guy at work that I can use something like acetone or paint thinner to remove any varnishing inside, is that true? If it is, I have a huge can of paint thinner already and wouldn't mind putting it to use.

I have removed the bed in prep for this job and did not see any rust spots but will further inspect everything just to be sure... I plan on removing and plugging the fuel lines and covering the electrical plug to prevent water getting to them. The filler neck hose is getting replaced so that port would be covered with some thick drop cloth material and zip ties to prevent water from entering the tank. If I do accidentally get water in the tank, how would I remove it? Hypothetically if I did drain and "wash" the interior of the tank, how long would it need to air dry before I could install the sender and add gas to it? Looks like there will be a lot of elbow grease in my near future lmao

juggaloscorpio · Oct 28, 2016

YAY pictures!!

Top of fuel tank and my cracking filler hose

Mark_88 · Oct 28, 2016

juggaloscorpio said:
Top of fuel tank and my cracking filler hose

Mine was just as bad and I cleaned it with a shop vac...of course, I did also use a wire wheel to take all the rust off the frame and then painted that part...but the lid of the tank was pretty funky with dirt and grease and it came off as I mentioned above...a nylon brush and a shop vac.

Can't tell from those pictures and this view isn't allowing me to see what year your truck is...biut if the tank is metal it might need a bit of cleaning...if plastic it is probably fine. I think they started putting the plastic tanks on around the early 90s...my 88 had a metal tank but my 92 had plastic...

EDIT: OK...so 1996 your tank is plastic...I wouldn't worry too much about cleaning inside...and the outside isn't going to rust...but I'd be a bit careful with any solvents on or around that...they can go boom but usually don't unless you are using open flames or sparks...

tomw · Oct 29, 2016

A plastic tank won't rust. It will therefor not create rust particles to clog things up. It will not 'hold' any deposits of dirt or degraded fuel. They won't stick(at least not very well).
It should be a 'rinse out' type cleaning if even that is necessary. As Mark said, the outside should clean up easily also. I think a garden hose with nozzle would be good. Protecting the filler neck cracks makes good sense.
The only place that NEEDS to be clean is around the fuel pump 'neck'. Cleaning will reduce the chance that 'stuff' can get into the tank, assuming you plan on doing a R&R of the sender/pump assembly. Vacuum, brush, squirt away and get it clean there. A minimal cleaning for the rest, mainly to clean out places where water & salt can mix and accumulate with road dirt and form a nice mix to eat at the metal straps. IOW, clean out the nooks that have accumulated masses of dirt, twigs, leaves, clippings, etc. The rest, doesn't matter except for mental floss.
tom

juggaloscorpio · Oct 29, 2016

I removed the filler hose, both fuel lines, and the electric connected and covered/zip tied them with a heavy duty plastic which worked very good. I did a deeper inspection and the isn't much rusting at all anywhere around the tank but the frame is covered in "surface rust". Hypothetically, if I was to take a wire wheel brush to it, does it need to be down to the bare/shiny metal or just remove the surface rust? And what type of paint/sealant should I use on the metal afterwards? I do not have a spray rig or a garage to do "paint/body" work without dust and dirt being stuck in the paint, I have a driveway and I live in Texas hahaha

I used a nylon brush and my garden hose to clear away the dirt and grime and will be replacing the fuel pump/sender assembly unit later today. Hopefully Delphi sending units are decent quality lol.

Mark_88 · Oct 29, 2016

Good work on the cleanup... :icon_thumby:

If you just take off the surface rust with a wire wheel and then hit it with rust inhibitor it should be good to either use a rust paint or something like that rubber guard rocker panel spray. I also used a metal chisel and hammer to bang off the scale (shale) that was flaking on mine and that gets you down to the good metal.

There is also other stuff that might work better (Por 15???) and last longer but it requires both better prep and perhaps a face mask or protection for your skin and eyes...even outdoors...check out a few of the frame cleaning posts...Cvar posted a great frame off restore a while back...worth reading through and following if you are remotely serious about keeping this longer than a few years.

Well worth the investment of time and materials.

tomw · Oct 30, 2016

The frame will last, possibly longer than you, in Texas weather. Mark had good suggestions about slowing down the corrosion. There are spray paints, Rustoleum for one, that will slow the inevitable process enough that it is worthwhile.
Delphi was formerly a part of the GM parts 'train', supplying them with pumps, injectors, etc. It should be decent quality, but I would take a good look to see if their assembly procedure is checked. Some have found the short section of fuel line between the pump itself and the sender 'body & tubing' is installed properly. I have read / seen pics of where the assembler was on vacation or lazy, and the line was kinked or not installed onto the pump & tube. Take a look.
When I take the old one apart, I use what are called 'waterpump pliers', actually slip-joint pliers with about 5 different settings of the jaw 'width'. Use them on the tabs that stick up on the metal ring, squeezing to force the ring to un-screw. You do not need a hammer for most. Install is the reverse, just squeeze using the pliers. No sparks...
tom

juggaloscorpio · Oct 30, 2016

Looks like it was assembled with good quality as you can see both ends of the tube well within the rubber part and clamps. Unfortunately I did not get a chance to put it in this weekend, I am trying to give more time for the residual water to evaporate before removing the plastic from around the connection and lines. Since my daughter doesn't have karate tomorrow I will probably so it after work.

juggaloscorpio · Oct 30, 2016

Here are a couple late night pics of the cover up of everything and a little look at the cleanliness of the tank area. Hopefully it is clean enough for the replacement process with as little dirt dropping in the tank as possible. Positive note is that there is almost no gas in the tank so even if I do drop too much dirt in, I can easily soak up the gas and clean out the grit.

juggaloscorpio · Oct 30, 2016

The frame seems to be pretty sound and sturdy with very minimal rust(surface only as far as I can tell). Personally don't think it really needs the in depth restore but I am not a P&B guy but I have seen other vehicles in way worse condition to require that type of work.

Mark_88 · Oct 31, 2016

The tank looks good to go with the parts swap...and the frame will probably last a long time ...I didn't pay attention to your location until TomW pointed it out...it makes a huge difference where you are and what they put on the roads.

Although it doesn't hurt to do a bit of extra work when you can to try to make it look better and last longer it sometimes is a trade off...in Canada we use sand and salt or other materials to keep the roads from icing over and that stuff is very hard on metal frames and other parts...

Anyway, keep us posted on your progress...

tomw · Oct 31, 2016

First pics I've seen of a later model sending unit setup. Big plastic retainer instead of the 'interrupted thread' twist locker of old. Need a BIG pair of pliers for that one, or a strap wrench. Plastic doesn't get 'glued' in place by chemical/oxidative action, so it should come off readily. Looks as if you are read to go. I don't know what the book or instruction sheet says(if there is one) but whenever I've had plastic fasteners like that, they indicate to use 'hand tightening only', or 'tighten until snug, then go 1/4 turn' or similar. Do not get too wrench happy or you'll be taking a trip to find a new 'ring'.
tom

Fuel tank clean?

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