Fuel pressure

[Dino]

I spent some more time today driving around and trying to get the TQ to run right.  The floats are set to stock specs and I think it would run real nice if that one venturi would stop dripping.  I have now used 3 sets of o rings, the passenger side no longer leaks but now the driver's side does and no tweaking will stop it.  It runs and I can drive it but the car only gets happy at higher speeds.  Fuel consumption is through the roof.

I just realized that I retired my old stock fuel pump and installed a Carter M4845.  Now I'm wondering what the fuel pressure is as a TQ shouldn't have more than 5 psi if I'm not mistaken.

I'm not saying this is the cause of the problem, but it could be no?

I have one of those HF vacuum/fuel pressure gauges but the directions are a bit strange.  What's the best way to measure pressure?

I have an Edelbrock 1406 coming my way to do some more testing while I take the TQ apart again.  Those should run at no more than 6 psi I believe, can someone confirm that?

[myk]

I spent some more time today driving around and trying to get the TQ to run right.  The floats are set to stock specs and I think it would run real nice if that one venturi would stop dripping.  I have now used 3 sets of o rings, the passenger side no longer leaks but now the driver's side does and no tweaking will stop it.  It runs and I can drive it but the car only gets happy at higher speeds.  Fuel consumption is through the roof.

I just realized that I retired my old stock fuel pump and installed a Carter M4845.  Now I'm wondering what the fuel pressure is as a TQ shouldn't have more than 5 psi if I'm not mistaken.

I'm not saying this is the cause of the problem, but it could be no?

I have one of those HF vacuum/fuel pressure gauges but the directions are a bit strange.  What's the best way to measure pressure?

I have an Edelbrock 1406 coming my way to do some more testing while I take the TQ apart again.  Those should run at no more than 6 psi I believe, can someone confirm that?

Manual for my edelbrock 1411 says no more than 6.5 psi...

[Dino]

I spent some more time today driving around and trying to get the TQ to run right.  The floats are set to stock specs and I think it would run real nice if that one venturi would stop dripping.  I have now used 3 sets of o rings, the passenger side no longer leaks but now the driver's side does and no tweaking will stop it.  It runs and I can drive it but the car only gets happy at higher speeds.  Fuel consumption is through the roof.

I just realized that I retired my old stock fuel pump and installed a Carter M4845.  Now I'm wondering what the fuel pressure is as a TQ shouldn't have more than 5 psi if I'm not mistaken.

I'm not saying this is the cause of the problem, but it could be no?

I have one of those HF vacuum/fuel pressure gauges but the directions are a bit strange.  What's the best way to measure pressure?

I have an Edelbrock 1406 coming my way to do some more testing while I take the TQ apart again.  Those should run at no more than 6 psi I believe, can someone confirm that?

Manual for my edelbrock 1411 says no more than 6.5 psi...

Good to know, thanks!   

As much of a pain it is to get to the pump now, I'm actually hoping this may be part if not all of the reason why this thing keeps flooding.

I'm curious to see what the 1406 will do.  I don't expect it to run great at wot, but it should run real nice on the primaries.

[flyinlow]

Eddy carb manual says max 6psi. Adjust to 5.5psi if you have a regulator. I have mine set at 6psi. TQ, Eddy 800 and Quickfuel 780  carbs all seam to work at that number.

'73 FSM shows 3.5-5 psi pumps for standard 400-440. 6-7.5 psi for high performance 400-440. These would be Thermoquads.

[Dino]

Thanks!  The next step is getting the actual pressure.  Can I disconnect the hose at the vapor cannister running to the carb and hook the gauge up there?  Am I supposed to put the gauge between the pump and carb so the car is actually running or just connect gauge to pump and crank?

I'll have the Eddy 1406 tomorrow but probably won't bolt it on until Friday.  I run a hard line to the TQ and I doubt it'll fit the Edelbrock so I'm just going to run a rubber line from separator to carb for now.

[flyinlow]

If you just want to see what pressure the pump can make ,you can just run the line into gauge.  You can run the engine on the fuel in the carb long enough for this test.

A better test would be Tee into the the line between the pump and carb or between the regulator(if you have one on the car) and the carb. If you can mount the gauge where you can see it while driving ,that would be the best option.  I have duct taped a gauge to the windshield for this test. Route the temporary lines securely away from headers.

[firefighter3931]

A better test would be Tee into the the line between the pump and carb or between the regulator(if you have one on the car) and the carb. If you can mount the gauge where you can see it while driving ,that would be the best option.  I have duct taped a gauge to the windshield for this test. Route the temporary lines securely away from headers.

Exactly how I've done it....only way to know how steady the fuel pressure is under load. 


Ron