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I am hard over on a '39 Six resto and have been trying to solve a somewhat mysterious condition with engine operation. The car starts, idles and runs quite well (no smoke, no knocks, decent idle, etc.) but when driving, it just quits when idling up to a stop sign. I added a new (rebuilt) carb and, although it runs better (smoother idle, running and more power) the stalling issue continues. The fuel pump looks 'recent' with shiny new screws, so I am wondering if anyone out there has ever run into this, or if it smacks of anything 'predictable'?? I am not a mechanic (obviously!) and would like to eliminate the fuel pump. Is there a sure-fire way to 'test' it??? Any suggestions?

I didn't find a printed spec for 39 fuel pumps other than output pressure is 3 to 4 psi. On some other years, Packard gave fuel pump delivery specs in addition to pressure. The delivery spec was 1 pint in 45 seconds at idle speed and that spec was consistent over the years they gave one so I would suspect it is valid for 39 too.

You could provide a temporary separate fuel supply and gravity feed the carb using a gas can or similar so the engine will run. Provide another can the fuel pump can pump into. Run the engine for the 45 seconds at idle speed and then measure the quantity of fuel delivered. If it is close to the pint then I would suspect the pump is OK.

You might also read over a thread at the main Packard club.packardclub.org/forum/viewtopic.php?f=6&t=2123 There is a gentleman with a 40 120 with the same symptom. Several pages are in the thread and I didn't go back and read them but IIRC, he finally did find something and was able to resolve the issue. Perhaps some of his experiences will give you an idea.

Usually the problem you describe it due to too slow of idle speed.

If the fuel pump pressure and volume check out go back to the basics and start with the ignition system.

Check the spark plugs for condition and proper gap.

Check the distributor points for condition and proper gap.

Check the ignition timing for proper setting.

Make sure the carburetor idle is adjusted properly for speed and mixture. Idle mixture screw about 1 1/2 turns out.

Sometimes there will be wear in the accelerator linkage and when quickly released, like when coming to a stop sign, the linkage will go to a worn position that will result in a too slow speed.

A tricky problem to solve, but it can be solved. Good luck.

(o{}o)

I would check the coil

Quote:

Good suggestion. When it stops running, crank the engine with the key on and see if there is a spark between the ignition wires and spark plugs. No spark, an ignition system problem. Condenser or coil (as suggested above) likely culprit.

(o[]o)

You might also listen and look carefully around the intake manifold and the base of the carburetor, to see if some extra air is getting in and changing the mixture, due to an old gasket. Ernie

One more point...I just looked at the thread from Bob Hattler (sp) and after several years, the idle orifices in the carburetor were the culprit. If I were you, I would read Bob's description carefully...Ernie

Does it restart right away?

Thank you to all who replied; great suggestions, info and guidance. A friend gave me some hands-on help with this and we put a small length of clear fuel hose and a clear fuel filter right before the 'new' carb. When the engine died we could see it was a fuel delivery problem. We also checked the fuel pressure output of the pump and found when the engine was cold, it delivered about 4-5 PSI, but when the engine warmed up, the gauge fluttered and the pressure became erratic and diminished. (down to 1 1/2 - 2 PSI.) It ran fine at an idle but as soon as high-gear fuel demand required more gas, it starved and quit. I do not know anything about these vacuum assisted pumps, but for now, to be able to drive the car, we installed a 6 volt electric pump and that appears to solve the stalling problem. The car seems to be running a little hot to me, (we shot it with a heat gauge gun and it is getting pretty close to 200 deg's F on the head) and that is a whole new can of worms, but at least it RUNS, and I can look into the next set of problems/solutions. Thanks again for all the help.

Good to hear you found a solution, but.......

If you're loosing fuel pressure, one thing that could be is a fuel leak. You haven't mentioned any apparent leak, which would be obvious, so could be in the pump itself. The pump could have a cracked/split diaphragm in the fuel pump part of the pump. The vacuum side of the pump is separate from the fuel side, or should be, so shouldn't be an issue here. If it is the diaphragm there's probably fuel in the oil which, if there is, will dilute the oil and won't do your engine any favours. Please check your oil to see if there is any fuel contamination. And, rather than the band-aid electric pump fix, you'll be better off finding and fixing the real problem.