Re: '55 fuel line issues
Posted by HH56 On 2019/3/17 16:50:26
As with any fuel line, if it has lost one of the clamps and is rubbing against the frame somewhere a wear spot could develop and allow air to enter. There may or may not be a wet area around the spot with a pump in the line past a hole but if the electric pump is at the rear and pushing fuel past any hole then moisture would probably be present. An accidental crimp in the line caused by something hitting it is another thing that has affected flow. If there is rust sediment in the tank, flakes of rust could have been sucked into the fuel pump and there could be enough circulating in the sediment bowl to intermittently clog the inlet screen in the bottom of the pump. The electric pump might have enough pressure and volume to push enough fuel past the clog to keep the engine running. If you have one of the ceramic fuel filters next to the carb it might look clean but varnish has been known to clog those sufficiently that air and some fuel will still pass but full fuel flow is restricted enough to just barely keep the engine running at not much more than fast idle.
Others have experienced sediment or trash in the tank being sucked in to the small pickup area below the fuel inlet and momentarily block fuel delivery. Another known issue is rust pinholes in the pickup line inside the tank which allows air to be sucked in. The mechanical pump will have issues with this since air will be a significant part of what the pump can pull but unless the hole is large the greater flow and delivery of the electric pump can frequently overcome the added air and deliver enough fuel to keep the car running. The pinhole issues can become obvious in a couple of spots as the fuel level in the tank drops below the pickup tube exposing the holes to air. One spot is just below half full and the other is right around a quarter full.
If the gas cap has been changed recently, Packards need a vented cap. One fairly common issue has been the inadvertent use of a modern non vented cap which because of the suction of the pump and a sealed cap eventually causes fuel delivery to stop.
Here is a photo of the inner 51-6 tank that Ross provided. Some arrows have been added showing where the pinholes and blockage problems develop.
Attach file:
(114.07 KB)
Others have experienced sediment or trash in the tank being sucked in to the small pickup area below the fuel inlet and momentarily block fuel delivery. Another known issue is rust pinholes in the pickup line inside the tank which allows air to be sucked in. The mechanical pump will have issues with this since air will be a significant part of what the pump can pull but unless the hole is large the greater flow and delivery of the electric pump can frequently overcome the added air and deliver enough fuel to keep the car running. The pinhole issues can become obvious in a couple of spots as the fuel level in the tank drops below the pickup tube exposing the holes to air. One spot is just below half full and the other is right around a quarter full.
If the gas cap has been changed recently, Packards need a vented cap. One fairly common issue has been the inadvertent use of a modern non vented cap which because of the suction of the pump and a sealed cap eventually causes fuel delivery to stop.
Here is a photo of the inner 51-6 tank that Ross provided. Some arrows have been added showing where the pinholes and blockage problems develop.
Attach file:
(114.07 KB)
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