Packard Forum Index » V-8 (1955-56)

Hello having a big issue with my 56 400. My car is not getting fuel up to the carburetor. I replaced my fuel pump with a newly rebuilt unit. Pressure tested the line from the front to the back of car no leaks. Dropped tank no issues but I heard the pickup could be sucking air. Cannot see the pickup from the center of the tank. Going to drop the tank again and bring it to a shop going to try to drop another line to replace pickup. Any help on this would be appreciated.

One thing that has caught several having fuel delivery issues is an unvented gas cap. If you have replaced it check that it is vented type and if you have a vented cap, make sure the tiny hole is open.

The gas tank pickup tube issue happens in a couple of places. When fuel drops down just under a half or right around the quarter mark areas of the pickup tube that have been found to be prone to pinholes are uncovered. If your problem consistently happens at those points then suspect the pickup tube but if it happens with a tank over half full then suspect something else.

A problem could still be in the tank but then I would look toward something floating or moving around and somehow getting in the small triangular depression on the bottom of the tank and being sucked up to block the pickup tube inlet. Dirt or rust flakes can do this and if the tank has been treated with one of the sloshing compounds, those can cause problems if the tank was dried laying down and the bottom flat.

If you do find a tank issue then depending on what a repair cost might be, it could be more advantageous to buy a new repro tank.

Here is a photo Ross posted with the two known problem areas in the tube noted.

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  51-6 inside pinhole locations.jpg (112.38 KB)

Also, don’t forget to replace the rubber hose to the pump as they tend to close up internally with age.

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It is a lot less likely that your pump is "sucking air" from the tank than it is leaking or sucking air from the flex line at the fuel pump.

These rubber hoses dry rot/smog rot and can have dozens and dozens of tiny slit cracks in them when they age. Quite often these little slits are not revealed visually unless you remove the hose and bend it in good lighting. Then the slits become obvious.

Don't go after a mosquito with a sledge hammer. I have owned lots of V-8 Packards over many years. I learned long, long ago. Whenever you have a problem like this, first thing to inspect and replace is the flexible connection at the fuel pump— even if seems to look okay. If this doesn't correct the issue... then look to the tank.

I was referring to the hose delaminating and closing up internally which is a very common thing and it is totally invisible from the outside. It happens to the rubber brake lines too even with the hose feeling pliable and soft.

I've encountered a number of the fuel pump flex hoses that look great and do not leak, yet will not allow the fuel pump to work. I'd think that any hose that leaked air in would leak fuel out, but that is not always the case. I don't know of a reliable test for these items, other than to replace with new, fresh stock, if available, or temporarily substituting a length of rubber fuel line clamped in place.

Rather than assume I'd do some troubleshooting. Disconnect the flex hose from the fuel line to the fuel pump and insert into a small container of gasoline and see if it pumps from there. If so, do the same at the gas tank, where you'll have to disconnect the metal line and slip a hose onto it into a container and see if it draws from there. This should narrow down where the problem is.

So i am kinda relieved as this was just a simple fix. I did get the carburetor rebuilt so when i was installing the carb I had the Carter fuel filter to install. Just for the heck of it i blew through and it was clogged. I cleaned the best i could and installed it and now engine is working and I took it for a ride around the block no issue. I ordered 2 new stones but what can I clean the dirty one with in the meantime?