Present day gasoline probably has enough alcohol already in it to absorb the water that used to collect in tanks.

quote:

Originally posted by bill h:
Present day gasoline probably has enough alcohol already in it to absorb the water that used to collect in tanks.

I agree. Except for Florida this winter, I haven't seen water in the gas for years, it comes with ethanol "drygas" already in it.

Evidently when I filled near Everglades
city, I got some really lousy over-watered gas. I plugged several inline filters on the suction side with suspended cloudy water which collected in the filters. Worse yet, it aggravated another old problem... the sock filters in the tank are getting plugged with the years of crud that can never leave the tank. It collects on the socks, especially when the water blobs collect it on the tank bottom.

I have never liked in tank filters because they can not be serviced and the tank crud can never be removed. I much prefer oversize filters just outside the tank... change the filter and the crud goes with it.

After the latest round of fuel starvation/supply problems in Florida, I will soon be installing a threaded flange on each tank bottom. This will allow fuel to be taken from the bottom of the tank, straight into the filters, bypassing the sock strainers. Also gives me a way to drain the tank, which is not possible now without siphoning.

This should be the final solution to many rounds of fuel starvation and supply problems I've had. I will post the photos when it warms up and I get to it.

quote:

I will soon be installing a threaded flange on each tank bottom.

That's a great idea Steve, what type of flange are you looking at installing is this a speciality flange made for a fuel tank? So you're going to supply your external fuel pump from this flange?

I really like the concept I was looking at my setup and I have the internal fuel pump and the fuel regulator is tucked inside the frame rail, impossible to get to without dropping the fuel tank, and that doesn't look like a easy job. So I'm thinking new external fuel pump, new fuel regulator mounted where I can service it. Interesting!!

Good questions! I have not decided on the type of flange... if I pull the tanks I could get a flange welded on but I'd rather not.

For now, I'm looking for an alternative I can do in the vehicle. I have a 3" steel flange that I may install with epoxy, blind rivets and overlay with fiberglass mat. I need to check on the epoxy specs to be sure it will stand the gasoline.

I was hoping to get at least one tank done before Milford. Pictures will follow!

I consider the fuel system to be the Achilles heel of the older GM chassis. Considering all the changes GM made over the years, they would probably agree. So far I have replaced the regulator and installed the inline fuel pump when one of the in tank pumps failed. I much prefer one easy access pump to 2 ancient in tank pumps. I will also have MUCH larger filters.

to be continued on a new thread:

Ours has a drain plug, apparently factory installed.

I installed a drain in a tank in a truck once. I bought a B&M trans pan drain and dropped the nut down the filler neck. I used a powerful magnet to move it in position over the hole and put it together. I used a center punch to dimple the underside of the nut so it would not spin inside the tank when I tightened the fitting from the outside. Every dimple made a raised area around it, so it worked pretty well.

BTW, I ran the truck dry and then jacked it up on an extreme tilt so there would be no residual gasoline where I cut the hole. I used a hole saw at a very low speed, driven by an air drill to avoid distortion or sparks.

Welding a bung on a gas tank is the best, though. When I weld a gas tank, I remove it and drain. Then I run a hose from a vehicle exhaust or even a lawn mower and let it run until the tank is warm to the touch. The heat releases residual gasoline from the inside and the carbon monoxide assures there will be no combustion. then weld away.

Resist the temptation to use water to purge a tank. I remember a small tanker truck that was purged for several days of running water, and still blew up. Blew the roof off the welding shop. Apparently the pores of the metal still had some gasoline that released when the welding commenced. Nobody hurt, but it was the loudest noise any non-vet had ever heard.

I used to use dry ice when welding motorcycle tanks but the exhaust fumes work as well or better, since the heat adds some function.

As far as epoxy goes, I would be wary. the FAA does not allow any airplanes with fiberglass tanks to use ethanol-containing automotive fuel. Epoxy or polyester.

quote:

Originally posted by bill h:
I installed a drain in a tank in a truck once. I bought a B&M trans pan drain and dropped the nut down the filler neck. I used a powerful magnet to move it in position over the hole and put it together. I used a center punch to dimple the underside of the nut so it would not spin inside the tank when I tightened the fitting from the outside. Every dimple made a raised area around it, so it worked pretty well.

As far as epoxy goes, I would be wary. the FAA does not allow any airplanes with fiberglass tanks to use ethanol-containing automotive fuel. Epoxy or polyester.

I like your trick with the inside nut and a big magnet, I could go that route.

The tanks are nearly empty now. I was planning to punch a small hole to let it finish draining, then purge the tank (exhaust is good, CO2 or nitrogen will work also, really, anything without oxygen) I will end up with 4 holes, 3 for the flange rivets and one for fuel in the center. I will use hand or air tools only to drill the holes.

The FAA is very conservative, for good reason. I am also leery of fiberglass tanks, although I have a 19 gallon fiberglass tank in my 1987 boat which is doing fine...

I would never use polystyrene resins for this. I think that is what some of the cheap "fiberglass" layups used. I was thinking of bonding the 3 inch flange to the tank bottom with the proper epoxy and 3 blind rivets, then overlap the whole thing with a 5-6 inch fiberglass epoxy mat, leaving a hole in the center for the bung. This would leave a large area bonded with only the inside perimeter of the holes exposed to the fuel.

I still have to look at my epoxy choices. My father worked with epoxy a lot during his time at Dow chemical. He designed and ran chlorine cells. I will see what he says about gasoline resistance.

Hopefully I can do this and post it soon.

quote:

Originally posted by Steve VW:

The FAA is very conservative, for good reason. I am also leery of fiberglass tanks, although I have a 19 gallon fiberglass tank in my 1987 boat which is doing fine...

Is it epoxy or polyester? Regardless I would pull it out and check for softening. A small amount of fumes can go bang. I have positive air flow under way, and always run the bilge fan for a few minutes before starting up.

quote:

I would never use polystyrene resins for this. I think that is what some of the cheap "fiberglass" layups used. I was thinking of bonding the 3 inch flange to the tank bottom with the proper epoxy and 3 blind rivets, then overlap the whole thing with a 5-6 inch fiberglass epoxy mat, leaving a hole in the center for the bung. This would leave a large area bonded with only the inside perimeter of the holes exposed to the fuel.

If you use enough rivets and get a tight fit on the flange, THIS is pretty good.

THIS has worked well on my daily motorcycle.

Another way to attach a flange is to make a retainer ring (using two hole saws of appropriate diameters) and drill and tap holes for the bolts. Then, cut it in half and fit each half up through the hole and place in position. Be sure of hole alignment. Smear some of the Permatex on the flange and bolt it together.

BTW, be sure to use steel rivets. Bad things happen to aluminum rivets in the bottom of a steel gas tank in the presence of water. I don't know if that is so much of an issue with the ethanol content of today's gas, though.

quote:

I still have to look at my epoxy choices. My father worked with epoxy a lot during his time at Dow chemical. He designed and ran chlorine cells. I will see what he says about gasoline resistance.

A lot has changed with the advent of ethanol in gasoline. Perhaps your dad still has contacts at Dow. I used to swear by Marine Tex tank repairs. No more.

Sounds like your gas filter is dirty. It is located along the right frame rail. Just follow the gas line from the tank. A new one is about $3.00.