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Author
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Topic: fuel pressure loss
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3154tm
Journeyman Posts: 37
From: Pensacola, Fl
Registered: Feb 2006
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posted 08-14-2006 05:06 PM
 
within a few minutes of starting the fuel pressure slowly drops to zero at the gauge and the glass filter at the carb goes empty. the inside of the tank is spotless and the pickup is clear. the system has new hard and soft lines, new marine type filter near the tank, new electric carter fuel pump, new holley regulator and gauge, new inline filter w/ sight glass just before the carb, and new edelbrock 4bl carburator. i can't find any obvious leaks between the tank and the carb and there don't seem to be any leaks in the carb. the pump nozzles aren't leaking and i don't see any gas leaking down the the throats of the carb. it doesn't seem to be a tank vent problem because taking the cap off doesn't help. i've even tried another electric pump. same problem.
has anyone had any problems w/ the holley regulator? this problem is making me crazy. any suggestions?
thanks.
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SteveLaRiviere
Administrator Posts: 48752
From: Saco, Maine
Registered: May 99
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posted 08-14-2006 08:13 PM
Have you adjusted the regulator? Tried it without the regulator?Are you getting enough voltage at the pump? Big enough wires? ------------------
'70 Mustang Mach 1 - '70 Mustang Convertible - '72 Mustang Sprint - '94 F-150 XL
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3154tm
Journeyman Posts: 37
From: Pensacola, Fl
Registered: Feb 2006
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posted 08-14-2006 09:23 PM
steve,
the pump is wired to the battery through a relay using 12awg wires less than 2ft long. when i checked there were 13.5 volts at the pump with the engine running. dialing in more pressure at the regulator just slows the drop down.
tommorow i'm going to bypass everything and wire the pump directly to the battery, skip the regulator, and tee the pressure gauge in line and see what happens.
frank
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Hemikiller
Gearhead Posts: 726
From: Killingworth, CT
Registered: Feb 2002
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posted 08-14-2006 11:05 PM
Do you have a liquid filled gage? If so, try a cheapie dry gage, it may solve your problem.
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Fordwiser
Gearhead Posts: 535
From: Metamora, Illinois
Registered: Dec 2000
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posted 08-15-2006 12:57 AM
Is the filter before the pump or after? Some pumps don't suck to well, also is the filter and pump lower then the tank?Roger
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3154tm
Journeyman Posts: 37
From: Pensacola, Fl
Registered: Feb 2006
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posted 08-15-2006 10:45 AM
thanks for the replies.
yes it is a liquid filled gauge.
the filter is before the pump and both are lower than the tank. the carter fuel pump is only rated at 7psi max but this should be enough for an edelbrock carb if the pump is working correctly.
when i bypass everything i'll use a dry gauge i can rob from another car.
any other suggestions?
frank
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3154tm
Journeyman Posts: 37
From: Pensacola, Fl
Registered: Feb 2006
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posted 08-15-2006 11:24 AM
the folks at holley finally answered the tech line. they said that the liquid filled gauge can become pressurized as it heats up under the hood. when this happens the needle slowly drops. to bad they didn't mention this in the installation info since high underhood temp is to be expected. they said if the gauge is mounted vertically, to use a needle and poke a hole through the plastic plug on the back of the gauge to relive the pressure. sounds like a crude solution. i'm going to try this before i go any further.
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