Jump to content

Surge Tank Float Switch(es)


drgrumpus
 Share

Recommended Posts

We did just that, ordered it from automation direct for around 20 bucks. Make sure you buy one that has a specific gravity that will float in gas! Took me twice to figure that one out  ^_^  pretty sure the one we used was made of "kynar" or something like that. Just a plastic that will hold up to fuel exposure and also float. 

 

Just a heads up - the only issue we have had with our system is whenever I route the fuel return through the surge (then the surge vents back to the cell) we end up getting false readings from the float switch. I am not sure if there is a slight vapor lock issue or what, but there is something it doesn't like about our return line running back to the surge. When I run the return line directly to the cell, we do not seem to have that issue. At Daytona this year I had the return line routed to the cell - no problems, no false readings from the float switch. Sebring I went back to running the return line through the surge - back to having some false readings.

 

Edit: Looks like they've gone up a couple bucks...

https://www.automationdirect.com/adc/Shopping/Catalog/Process_Control_-a-_Measurement/Level_Sensors_-a-_Controllers/Float_Level_Switches/FLS-HM-300

Edited by pintodave
Link to comment
Share on other sites

I run an overflow line from the top of my surge tank back into the fuel cell. My EFI system is returnless so that line was available.

 

I used a stock GM fuel tank cartridge and built a surge tank around it, using the stock fuel level gauge as the low fuel switch. I moved the resistive wires at the upper end of the rheostat so that when it's full, there is no current. When the float drops to about 3/4, it contacts the wires again and activates a relay that turns on my low fuel light.

 

The light comes on when cornering at more than about 0.8gs to the right, so I tell my drivers that when the light stays one full straight, it's time to pit.

Edited by mender
  • Like 1
Link to comment
Share on other sites

3 hours ago, drgrumpus said:

 

thanks for the info.  I wonder if returning to the top of the surge tank is upsetting the float switch.  I plan to return to the bottom of the swirl pot.

 

 

 

That is one other possibility we thought about. It could just be a design flaw in the way the fuel is circulating between the lift inlet and return line. Very plausible. 

Link to comment
Share on other sites

I just didn't trust the small senders so I installed a 10 psi cracking pressure ball check valve in the line from the main tank to the surge and installed a fuel pressure sender in the line in front of it.  Gauge in the panel displays about 15 psi until the main tank starts picking up air then you can see it bobble, time to come in.  Works slick.

  • Like 3
Link to comment
Share on other sites

On 11/24/2017 at 6:18 PM, Burningham said:

I just didn't trust the small senders so I installed a 10 psi cracking pressure ball check valve in the line from the main tank to the surge and installed a fuel pressure sender in the line in front of it.  Gauge in the panel displays about 15 psi until the main tank starts picking up air then you can see it bobble, time to come in.  Works slick.

Got a link?

Link to comment
Share on other sites

4 minutes ago, Xph said:

 

Yes, as in is it a commercial part, fittings etc?

 

Yes, there are several options but what I bought was a 3/8" NPT Hy-Lok with a 10 psi spring model CV2-H6T-10-BRAS.  I bought it from Nikki at MVF Process Controls 251-633-4333 but you may have to look up your local rep for Hy-Lok.  Make sure you order it with the correct elastomers for gasoline, but I think the model reflects that, just can't remember without looking at the table again.

 

 

 

Link to comment
Share on other sites

2 minutes ago, Burningham said:

 

Yes, there are several options but what I bought was a 3/8" NPT Hy-Lok with a 10 psi spring model CV2-H6T-10-BRAS.  I bought it from Nikki at MVF Process Controls 251-633-4333 but you may have to look up your local rep for Hy-Lok.  Make sure you order it with the correct elastomers for gasoline, but I think the model reflects that, just can't remember without looking at the table again.

 

 

 

 

ok, so that was entertaining, googling just that part number...  best bras on the internet... lol...

 

So thats a check valve, then I assume you use some sort of pressure gauge?  I would think a on off switch with a light would be optimal. 

Link to comment
Share on other sites

Like this

 

http://www.dieselmanor.com/docs/bd/BD-1081130FPalarm_inst.pdf

 

5psi pressure alarm switch...   so you need the restrictor in your return line and a light like the above.

 

here is a 17$ oil pressure switch...

 

https://www.amazon.com/Briggs-Stratton-491657S-Pressure-Replaces/dp/B002WNYB6C/ref=pd_sbs_86_6?_encoding=UTF8&psc=1&refRID=J359JBKC1VPYZGN3T79F

 

or a 10psi part for a bit more

 

https://www.amazon.com/Generac-Pressure-Switch-10PSI-060108/dp/B000OLORDQ/ref=pd_sbs_86_22?_encoding=UTF8&psc=1&refRID=3HXPRJJ836MQ76596N8X

 

thinking those would work for fuel maybe

 

Edited by Xph
Link to comment
Share on other sites

 

7 minutes ago, Xph said:

 

ok, so that was entertaining, googling just that part number...  best bras on the internet... lol...

 

So thats a check valve, then I assume you use some sort of pressure gauge?  I would think a on off switch with a light would be optimal. 

 

I bought a 0-30 psi gauge from GlowShift for my gauge panel, installed the sender for it in between the tank pump and this valve.  Displays 17psi to the surge tank until the main tank runs out, then it bobbles.  You have 1/2 gallon to get to the pits.  But you are right, a light might be better to get your attention.

 

Edit: Didn't see your second response.  Yeah, that looks like that would work well, good idea.

Edited by Burningham
Link to comment
Share on other sites

  • Members

I use a sender from aircraft spruce. The one I have has a warning light and a fuel gauge level. These come 12" long and can be cut back to like 6" or so. Then you have three knobs to adjust the low, high and warning light activation. I have a gauge and warning light. I have the low fuel set at like 3/4 and can see it come on. It helped me at AMP as the warning light came on as it went below 3/4 with 2 hours to go and I totally babied it as I watched the fuel level go lower and lower I sent. I did see it go down to like 1/16 and would surged fuel from the surge tank and was in massive fuel conserve mode. I could manage how I drove to get me to the finish and without it I do I think I would have finished. 

 

http://www.aircraftspruce.com/pages/ep/fuelsender/falconDualFuel3.php

 

I used this gauge with it. 

http://www.aircraftspruce.com/catalog/inpages/f2-001-5.php?clickkey=3629

 

The output voltage is 5v for the warning light. 

https://www.ebay.com/itm/1-Channel-Opto-Isolated-Relay-High-Low-Trigger-5-Volt-Screw-Terminals/263063281463?epid=1531758911&hash=item3d3fcb1f37:g:QX4AAOxy4t1SnNQF

 

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...