Gas Tank Foam

[Mek-a-nik]

Hello Folks! I haven't been on here for quite some time. I hope all has been well with everyone. I closed my business 5 or 6 years ago, but still repair things for friends and neighbors.
I'm working on a Craftsman tiller with a Briggs 137202 0116 01 960307YD. Only runs on a prime. It had old gas in it, but it also has that foam-like stuff in the gas tank. I remember reading about that stuff on here, but can't remember, of find in a search, much about it, other than it disintegrates. That's what's going on here. The pick-up screen is covered with tiny bits of the stuff.
There's no rust in the tank. Can I just remove this stuff without worrying about slosh, or whatever the foam was doing in there?

[KE4AVB]

With foam disintegrating the only option that I know of is to remove it. Just be aware sloshing could be problem but with these tanks no available there is not much choice. May someone here knows of something that compatible with gasoline that could be used.

[Mek-a-nik]

Thanks for that, KE4. If it'll be ok without the foam or anything else, I'm good with that. Maybe when the fuel level gets low, it might be an issue, but that's no biggie- fill er up!
I wonder why Briggs put it in there? Maybe for when the engine was used in a specific application?

[bgsengine]

Briggs put it in there where the engine was being specified for a high vibration application such as wood splitters, roto tillers, etc as the gas sloshes and/or jumps around and vibrates, (bear in mind this was before more stringent EPA rules, etc) gas would vaporize and/or leak out (gas cap vents, etc) and pose higher risk of fire/explosion from the hot exhaust , and secondly, it is to help prevent cavitation of the fuel (Air pockets that develop in the gas that can cause stall-out) it's similar technology to the fuel bladders used in race cars, I believe... But as KE4 said, if it has to come out, it has to come out, there's no putting it back in or replacing it.. TBH, I have never really noticed a big problem on these type engines, except some were prone to having fuel sloshing out the gas cap vent, so just have to be aware you want to make extra sure of your muffler condition, and probably make sure you don't store the machine until it is fully cooled down.. leave it outside til it's cool..

[Mek-a-nik]

Copy all of that, Brian! Makes sense. Thanks.

[Mek-a-nik]

Well, it took the USPS 3 weeks to mail an envelope from Maryland to South Jersey.

I have it back together and it still only runs on a prime. I flushed the tank, put the carb in my ultrasonic cleaner, put new tank to carb gasket and carb to head gasket. Also put in a new pump diaphram.

I put a new fuel pickup on the brass tube. I heated the brass tube with a propane torch, and put the plastic tube in boiling water for a while. It slipped on easily, and I used the tiny clamp that comes with the tube.

I took the fuel pump cover off, and realized I don't have the cap for the spring. I'll order one, but I'm just wondering if that's enough to keep the fuel from pumping?

Here's what I used for a reference: https://www.ereplacementparts.com/brigg ... 72802.html

[Skywatcher]

Hi Mek-a-Nik

On these carburetors, the diaphragm pump pumps a constant flow of fuel into the top chamber or the cup in the fuel tank, the carburetor then draws the fuel from that cup. Think of the cup as being the float bowl of the carburetor. If the cup is filling but the engine still won't run, there is a horizontally drilled passageway that gets plugged with fuel varnish or other debris. The only way I've found to properly clean this passageway is to remove the steel ball from the side of the carburetor and manually drill the crud out of that passageway then flush it through with carburetor cleaner.

There are two balls right next to each other, I forget off hand which one needs to be removed, but I'll check tomorrow and get back to you. Once cleaned out, tap the hole to 6-32 and cap off with a shortened machine screw. The block-off balls are soft steel so can be partially drilled through with a 1/16" drill, then pried out with a short length of 1/16" acetylene filler rod. When you put the diaphragm etc. back, just remember that it's spring, cap, diaphragm then diaphragm cover. I have had quite a few of these carburetors come in with the spring and cap installed in the diaphragm cover defeating the purpose of the pump. Intake vacuum pulls the diaphragm in and the spring pushes it out again. All the best,

Sky

[KE4AVB]

Also note Sky that the vertical passage going up the side the tower can be clog too. I only had a handful these with this passage clogged but most had rusted tanks that were. But it is same procedure of removing the steel ball at the bottom of the tower except I use a screw extractor once the ball is drilled.

[Skywatcher]

Hi KE4

Now you're talking about very small and easily broken screw extractors. Acetylene filler rod comes in 36" lengths so if the end get bent, cut it off and start again. The trick I've found is once the ball is drilled ½ to ¾ the way through, insert the rod and move it side to side, then in a circular motion (like the joystick on a video arcade game) to get the ball freed up in its cavity. Once the ball is loosened up, lay the rod over against the carburetor body and the ball pops out sideways. All the best,

Sky

[Mek-a-nik]

First, in fairness to Jack's Small Engine's, they didn't screw up my order, it was the USPS that took forever. Also, I used ereplacementparts for look-up only, then went to Jack's.

Anywho, thanks for your replies gentlemen.

The fuel bowl (thanks for the theory, Sky) is dry. So, I believe that points to an inoperable fuel pump or an air leak in the pickup tube. (The fuel bowl doesn't have any leaks.) The missing spring cap (I do have a new spring, too.) can't be helping, for sure. Also, I did have the pump parts installed in the correct order. I just didn't realize the cap was missing.

But I think I may have found the culprit: The plastic fuel pipe that I installed came right off in my hand. I'm thinking it was drawing air at that connection. There wasn't enough gas in the tank to cover that connection.

This carb was not fouled badly. The gas smelled "wrong", but no crud at all. I dug in thinking that the disenegrating foam had created obstructions. Before I go too far in this direction (regarding the small balls), I'm going to get the spring cap and a (another) new pick up tube. The brass tube is airtight. When i cover the hole in the carb that it leads to, I can't blow through it.

I think I over did the plastic pipe install. As I noted previously, I heated the brass with a torch, and sat the plastic piece in boiling water. I think the heat fatigued the clamp, as it was on the brass tube when I heated it. Also, the plastic tube seems to have been overheated. What's a good method to install it?