Surge tank inlet low presure warning

[Howard Jones]

I have begun to build my swirl/surge tank. See post-1206 above for the layout. Here's my question. I would like to install a low fuel pressure switch in the lift pump output from the main tank to the surge tank so that I would know when the main tank has run low on fuel and be warned that the surge tank is not being supplied with fuel. This will give me a lap or so of fuel to return to the paddock without running out.

But I don't believe that there will be much if any pressure in that line since it is in freeflow to the surge tank. The surge tank is vented back to the main tank by a open return line and the main tank is vented to the atmosphere. Therefore I don't think any pressure will be present in that line. If I install a low-pressure switch there it will be on all the time. Fail.......

I was thinking that a restriction in that line might provide some pressure differential but I really need about a constant 6 PSI to use a 4 PSI sensor/switch. That much of a restriction would be excessive? I have a leftover inline fuel pressure regulator. If I used this inline with the surge tank inlet, do you think it would provide enough restriction to use the pressure switch?

Has anybody solved this problem? Ideas?

 

[Randy V]

See my post on your build log related to this..

 

[Parris Ernst]

I have begun to build my swirl/surge tank. See post-1206 above for the layout. Here's my question. I would like to install a low fuel pressure switch in the lift pump output from the main tank to the surge tank so that I would know when the main tank has run low on fuel and be warned that the surge tank is not being supplied with fuel. This will give me a lap or so of fuel to return to the paddock without running out.

But I don't believe that there will be much if any pressure in that line since it is in freeflow to the surge tank. The surge tank is vented back to the main tank by a open return line and the main tank is vented to the atmosphere. Therefore I don't think any pressure will be present in that line. If I install a low-pressure switch there it will be on all the time. Fail.......

I was thinking that a restriction in that line might provide some pressure differential but I really need about a constant 6 PSI to use a 4 PSI sensor/switch. That much of a restriction would be excessive? I have a leftover inline fuel pressure regulator. If I used this inline with the surge tank inlet, do you think it would provide enough restriction to use the pressure switch?

Has anybody solved this problem? Ideas?

Howard, I'm about to pull the trigger on fuel pumps, swirl pot etc.. and noticed that you are in New Braunfels. I have a house there and will be stopping by this August 8-11 and would love to take a look at what you have going on your GT40. I can be reached at 808-489-3713. Let me know if a quick visit would be ok. I'm in Hawaii and building a RCR 40. Thanks, Parris

 

[Jean-Marc]

I have begun to build my swirl/surge tank. See post-1206 above for the layout. Here's my question. I would like to install a low fuel pressure switch in the lift pump output from the main tank to the surge tank so that I would know when the main tank has run low on fuel and be warned that the surge tank is not being supplied with fuel. This will give me a lap or so of fuel to return to the paddock without running out.

But I don't believe that there will be much if any pressure in that line since it is in freeflow to the surge tank. The surge tank is vented back to the main tank by a open return line and the main tank is vented to the atmosphere. Therefore I don't think any pressure will be present in that line. If I install a low-pressure switch there it will be on all the time. Fail.......

I was thinking that a restriction in that line might provide some pressure differential but I really need about a constant 6 PSI to use a 4 PSI sensor/switch. That much of a restriction would be excessive? I have a leftover inline fuel pressure regulator. If I used this inline with the surge tank inlet, do you think it would provide enough restriction to use the pressure switch?

Has anybody solved this problem? Ideas?

You may put a check valve inside (in reverse) and ajust the spring on the ball to get the pressure you wish

 

[Walter]

I have begun to build my swirl/surge tank. See post-1206 above for the layout. Here's my question. I would like to install a low fuel pressure switch in the lift pump output from the main tank to the surge tank so that I would know when the main tank has run low on fuel and be warned that the surge tank is not being supplied with fuel. This will give me a lap or so of fuel to return to the paddock without running out.

But I don't believe that there will be much if any pressure in that line since it is in freeflow to the surge tank. The surge tank is vented back to the main tank by a open return line and the main tank is vented to the atmosphere. Therefore I don't think any pressure will be present in that line. If I install a low-pressure switch there it will be on all the time. Fail.......

I was thinking that a restriction in that line might provide some pressure differential but I really need about a constant 6 PSI to use a 4 PSI sensor/switch. That much of a restriction would be excessive? I have a leftover inline fuel pressure regulator. If I used this inline with the surge tank inlet, do you think it would provide enough restriction to use the pressure switch?

Has anybody solved this problem? Ideas?

I use a back-pressure valve for the return line from swirl tank to main tank (this was recommended by Kinsler) as well as a pressure by-pass valve. This regulates the fuel pressure within a certain window under normal conditions (fuel being fed in to the swirl pot). On this you can base your low fuel pressure switch.