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MG MGB Technical - Fuel pressure question - facet pump

Just wondering if anyone has installed a fuel pressure gauge on a facet pump? I have a 2-4psi unit installed that seems to be running at about 1psi. I have a new tank, new 5/16" fuel line, all new connection hoses, and a Holley 1-4psi regulator, adjusted as high as it will go. The carbs are professionally rebuilt HS4s. Is this normal? What can I do to fix it? The pump is running off of a relay fed from the battery, triggered by the stock fuel pump wire. The wire to the pump is 14ga, and the pump is well grounded.
Jeff Schlemmer

Hi Jeff.

I don't know what smog equipment you have got, and guess you have thought of this, but... is there an adequate way for air to get into the tank, or is the pump trying to create a vacuum ?.

Don
Don

Well, I removed the rubber seal from the stock fuel cap, so as to have a vented tank. I believe its working, but I should double check. I have no smog equipment.
Jeff Schlemmer

If it's a venting problem, try drilling a couple of small holes into the inside of the cap inboard of the sealing surface. That'll vent it. I suppose your cap is still sealing too well even with the gasket removed. Should be easy to check....just remove the cap and see what happens.

I don't think you really need the regulator anyway. The 1-4 psi Facet doesn't put out too much pressure. I'm not sure how the regulator works, but could it be possible that it would need more pressure on the input side than the Facet is capable of?

If it's vented, no obstructions, and removing the regulator doesn't help, it sounds like a defective pump...
Joe Reed

Jeff,

I'm also running a Holley fuel pressure regulator in my B (with a fuel pressure gauge). In order to increase the flow, the "adjustment screw" needs to be screwed in, not out. Not sure if that is the way you are adjusting yours or not. Thought that it was worth mentioning.

Good luck!

Mark



Mark W.

Jeff - How is the car running? If it runs ok, then I would say, don't worry. It is hard to get an accurate pressure reading on the impulse type of pump into a closed pressure gauge. I check pressure on my test site by attaching the gauge parallel to a float bowl that has a calibrated outlet of approx. equal to 20 mpg (this is all very rough), even there you have to interpolate the average reading as it bounces from minimum to maximum. I have never checked the output pressure from the small Facets pumps so am unable to give you a figure. Good luck - Dave
David DuBois

Jeff,
Put the intake side of the pump into a can and check pressure. If the same, then the intake side is OK. Hook the gauge directly to the output side and check pressure - now you know what the pump is developing. When that's OK, check downstream of the regulator, then throw it away. You don't need it anyway, they are for pumps that have too much pressure.
FRM
FR Millmore

Thanks for all the advice so far. I'll start by removing the regulator. I had it in for a larger pump - a Carter 4-6psi unit. After having several people tell me to get rid of it, I finally listened, but waited to remove the regulator. It turns out that my problems with the Carter pump may have been with the regulator! I'll update my progress, hopefully later today.
Jeff
Jeff Schlemmer

I went back to stock arrangements with no regulator, and the back carb is once again fed from the front carb. Fuel flow has at least doubled!
Thanks!
Jeff Schlemmer

This thread was discussed on 13/09/2005

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