What does the strainer in an SC fuel tank do?

[Quickstep192]

I just got my new SC tank and the strainer that goes in the underside.

I can’t see how the strainer is straining anything. Can someone enlighten me ?

[Joe Bob]

If if is inside the tank....anti slosh.

[reclino]

The factory tank has a plastic surge tank, sort of shaped like a snail, its outlet is through the strainer, and out to the fuel pump. Aftermarket tanks are not set up for the strainer to function.

[smadsen]

My swirl pot/strainer had a few eucalyptus leaves & debris in it when I back flushed it & turned it upside down. Prolly didn't belong there (the debris). Prolly good maintenance every 200,000 miles.

[Quickstep192]

Originally Posted by reclino

The factory tank has a plastic surge tank, sort of shaped like a snail, its outlet is through the strainer, and out to the fuel pump. Aftermarket tanks are not set up for the strainer to function.

So, in the aftermarket tank the strainer just a $70 plug?

Makes me wonder why they bothered to put the threaded fitting in there?

[E Sully]

What aftermarket tank did you buy? Here is what was in the CIS tanks. If the tank is for the 1973, there is a CIS replica of the original for a full size spare I can PM you information on.
CIS Gas Tank

[Mark Salvetti]

Originally Posted by Quickstep192

So, in the aftermarket tank the strainer just a $70 plug?

Makes me wonder why they bothered to put the threaded fitting in there?

If you are talking about the Dansk tank, there is a swirl pot but no strainer. It comes with a threaded plug, you don't need to buy anything extra.

Mark

[PeteKz]

To state the obvious, the strainer keeps large bits from going down the line to the fuel pump where it could jam or damage the pump. I also installed an inline clear filter in the rubber line between the rear of the steel fuel line and the fuel pump, just to stop smaller contaminants from reaching the fuel pump. I had to replace the fuel pump due to crud in the old fuel pump. However, this car (1973.5 911T) had sat for 20+ years, so I had bad gas deposits and some corrosion in the fuel tank. Besides, you can never have too much filtration!

[Quickstep192]

The one I got is a Dansk tank (930-201-010-05/Dansk 1615600200), There’s something inside that looks the the swirl pot described earlier, but I can’t see (or it’s not obvious to me) how the strainer filters anything. It came with a strainer though, not a plug.

[75 911s]

Speaking from the factory tank, the thread in filter has a gap at the bottom of it, fuel leaves this gap and is taken to the fuel pump from there. That gap in the fuel filter is sealed off from the swirl pot and a standoff on the bottom of the tank under the swirl pot.

All fuel is taken in via the swirl pot either through the return line (above the filter), or an "admission" hole below and around the return line entrance on the swirl pot (which ultimately goes to the area in the middle of the swirl pot that is above the filter. Any new fuel from the tank (as well as the return line fuel) must go through the screen to enter the bottom gap below the swirl pot where the fuel pump out line is located.

If you click the link provided above in post #6 it has the detailed photos of the inside of the tank.

[Mark Salvetti]

Originally Posted by Quickstep192

The one I got is a Dansk tank (930-201-010-05/Dansk 1615600200), There’s something inside that looks the the swirl pot described earlier, but I can’t see (or it’s not obvious to me) how the strainer filters anything. It came with a strainer though, not a plug.

I had forgotten about this thread - seems Dansk may now be providing a strainer instead of the blank plug:
Dansk Fuel Tank Strainer Issues

Are you having the same issue as that OP, where the plug is not threading into place? If you go to the CIS Fuel Tank link posted earlier, the fourth photo in that thread has a label pointing to a “ Small Inner Gap”. Does your Dansk have that? You should be able to see it through the hole.

On a factory tank, the fuel pump draws fuel through that gap. There is a lip near the bottom of strainer that should seal against the top lip of the gap. See the oval openings at the bottom of the strainer? They align with the gap. Fuel flows into the top part of the strainer from the outside to the inside, and then back out through those oval openings and into the gap, then to the fuel pump.

If you don’t have the “Small Inner Gap” in your Dansk tank, you may have to trim the strainer to get the plug to seat. But as has been the case with all Dansk tanks in the past, that would make the strainer non-functional. Odd that Dansk is supplying a strainer instead of a plug as before.

Mark

[Quickstep192]

Here’s what’s going on inside my tank.

I want to think this means the strainer is actually doing something, but I’m keen for opinions from those more astute.

[75 911s]

Cool. Didn't know Dansk made a new tank with a strainer and swirl bowl. It's odd that there's no cap on the top of the swirl pot. Where'd you buy this from and how much was it? I've been wanting to buy this tank but site descriptions are less than forthcoming. Interestingly enough, one site has this Dansk 1615600200 part number, but says there is "no internal strainer" Searching it up on an auction site shows a tank and it is unclear whether it has a plug or just nothing at all where the strainer would go. Pelican's price for the same tank is over $100 higher... Is that because it contains the swirl pot and included strainer? Hmmmm

[Quickstep192]

I got it from Pelican and was glad to have someone to talk to that knew the difference between the tanks.

It’s Part #: 1615600200-INT

Here’s a link to it on the PP site. I still recommend talking to someone because even Pelican lists two tanks, one with the Porsche number and one with the Dansk number which are ostensibly the same thing, but might not really be.


https://www.pelicanparts.com/More_Info/1615600200.htm?pn=1615600200-INT

[Mark Salvetti]

Yes, that looks like a new design. The plastic shoulder just above the oval openings at the bottom of the strainer seals up against the underside of that circular silver-colored ring visible in the middle of the swirl pot.

If you take a photo up through the hole in the bottom, we should be able to see the narrow gap that feeds the line to the fuel pump.

This is great news for people that need a new tank. Now the strainer should actually work, and you don't need to worry about jury-rigging a filter on the fuel pump suction.

This is what the inside of the old design looked like. You can see that the suction line to the fuel pump didn't connect to anything in the swirl pot. There was no strainer or any way to make it work (borrowed the image from this thread: Dansk fuel tank, show me your in line fuel filter).



Mark

[75 911s]

Mark, Isn't the line on the right the return line? You can't see the feed line to the fuel pump in the old design. Anyway, that feed line probably is just an open pipe opposite the return line anyway.

"New design" has a baffle wall next to the swirl pot as well. This is great news for me because I was going to try to rescue my old tank because the new Dansk tanks didn't include baffles or swirl pots...


I think my price confusion was Pelican's third party supplier. INT vs M826 (internal code for the third party supplier)

Here's the M826 vender Dansk tank at nearly $90 more for the same Dansk part number on Pelican. It's the 930 part number, but the big print at the top says it's the Dansk 1615600200 which would be the same tank as quickstep bought but at around $90 more.

[Mark Salvetti]

Originally Posted by 75 911s

Mark, Isn't the line on the right the return line? You can't see the feed line to the fuel pump in the old design. Anyway, that feed line probably is just an open pipe opposite the return line anyway.

I think you are right, I was wondering that when I wrote it. But either way, as you say it was also an open pipe. No strainer.

Mark

[Quickstep192]

Here’s a picture of the strainer fitting. You can see the feed tube peeking through.



It also looks like the return is going into the outside “lane” of the pot which I guess keeps the fuel swirling around the strainer.

[75 911s]

I ordered this Dansk Tank based on the above info and it arrived yesterday.

1. The tank was damaged and the filler neck was poking through the side of the box when I got it. The filler neck was flat on one side where the box was dropped.



2. The tank was dented in two places, the places that show when you open the frunk.

3. The tank did not include the screen/plug.

4. The bag that contained the tank, was wadded up and placed next to an uncovered tank and it looked like the box was opened previously due to the "non factory" tape across the top flaps of the box. Check out this hole that was chiseled through 2 layers of heavy cardboard because the tank is ROUND and rocks back and forth when placed on an end. Please tell me that Dansk puts something inside to keep it from rocking and mine was just a return.



I've reached out to PP and they are returning it, and sending a new tank, but I guess I want to know if it really comes with the filter (gee it'd be nice if PP said what came in the box in their site description...)



Does Dansk really pack these that poorly? Or did I get a returned item sent to me from Pelican that someone hastily repacked the tank with no shipping materials inside?

Aside from it obviously being opened and taken out of the bag and then put back, is there not any foam to keep the round-ish tank from rocking around inside the box and poking through the cardboard?



Thought about straightening it, but these are the kinda things that haunt you forever and leak fuel. Every time I fill it up it could leak out here if it's not perfectly round.

[Mark Salvetti]

What a bummer. After all the excitement over Dansk finally building these with a strainer, you get a box of junk.

Mark