Packard Forum Index » V-8 (1955-56)

Hi guys hope you can help my 56 clipper won't start after 2 days unless I feed petrol into the carb. I have fitted a non return valve just below the fuel pump but it still happens? Also I want to fit new plugs the ones fitted at the moment are Champion N-16Y I think this I wrong N11. ？
Thanks Andy

1. Is the fuel pump functioning?

2. Is the carburetor accelerator pump functioning?

3. Curious why someone would install a non-return valve, they are completely unneeded in a proper functioning fuel system as there already is one inside the fuel pump. Any chance you installed it backwards?

N18s were used across the board for all models in 56. When I asked for set of plugs for my 56 back in the late 1980s, I was given a set of N16YCs. So, you should be OK there.

After starting the engine, do you have to keep feeding fuel, manually, into the carb to keep the engine running?

If so, then you may have a fuel supply problem. Check fuel pump output. However, before you go cranking the engine with the fuel line emoved from the carb, I strongly recommend that you disconnect the PRIMARY wire from the coil to the distributor.

If not, then you may have a weak accelerator pump in the carburetor. With the engine NOT running, hold the carb's choke valve open, look down the bores, and give the throttle shaft a twist. You should see a healthy squirt of fuel; if not, then it's time to rebuild.

JMHO, but since today's fuel is formulated for lower emissions and electronic fuel injection, hard starts have gotten harder.

The usual solution is to fit a small electric fuel pump back near the fuel tank. When the carburetor float bowls are full, starts are usually quick and easy.

jack vines

Another cause or adding to problem could be small hole in fuel line.
On mine I replaced the fuel line with two pieces of replacement line from NAPA one piece from tank to under floor on outside of chassis where original line was the other piece from from fuel pump back. The pieces were bought with a combined length greater than total original line then cut off ends added with inline pump mounted on rubber. Installed a switch under dash which is spring loaded for intermittent use hold on until pump quits working and carb is full. The other position on switch will have pump on always which I wanted in case mechanical pump should fail can use electric as back up.
Reason for mounting where I did rather than near tank was in case have to service pump or filter on road I can reach under car and get to pump rather than need for jack stands or ramps which I do not carry with me.

Attach file:

---

  (77.38 KB)

When those castings get old the valves start seeping and the pump empties. Another source is leaking well plugs in the carburetor. The air leak comment is also very good.

A good example of how a carburetor vehicle functions is as follows:

A restored 69 Chevelle sat over the winter in a 42 degree heated garage with the battery connected. 5 months later the car cranked for around 10 seconds and started. Of course you can still get new parts for a Chevy.

The absolute, most common all-time cause for this condition on Packard V8s is due to rot or hairline cracks that always, always eventually develop in the flex hose attached to the fuel pump. People will swear the line looks fine. They'll swear it's not leaking (and visually, it usually does not appear to be...after all the leaking is usually inward bound-not outward). But remove it, hold it up to the light and bend it. Usually dozens of tiny hairline cracks will reveal themselves.

In the end, the fuel pump works itself to death-not sucking gasoline from the tank... but sucking mere air from below the car. It is most easily noted when the carb won't fill and the engine has trouble starting. Today, this malady is most often blamed on all manner of other things, but the cause is often just this simple.

I know someone who went through one new fuel pump after another... and had all kinds of deep mechanical work done and strange diagnoses. Had to be the tank... had to be the carb... had the be the fuel pump... had to be the line from the tank.... when all the time it was a dry-rotted flex hose. Tried to tell him, but into the thousands of dollars later, the cause was the flex hose, like I said. Fixed it in 20 minutes.

Incidentally, this extra air in the line at this point also allows in extra moisture....which can have negative effects in both directions: the carb... and the tank. Moisture in the tank (a problem more common than ever today with the weird fuel blends) only gets worse with air being sucked and moisture joining moisture. The design of the fuel pickup tube in the tank with the sharp arc in the line is a typical spot for water, clogging and rust to accumulate. Many whole tanks are replaced solely for this reason.

Anyway, before launching into all other more complicated directions, your first remedy/countermeasure ought to be to replace the flex hose at the fuel pump. THEN see how things work and branch outward from there for further remedies. And even IF the fuel pump turns out to be defective, the cause may still have been the little flex hose allowing the pump to run dry and doing itself in.

If the fuel hose is porous it will suck in air which has humidity in it. The moisture cannot wind up in the tank as the fuel is flowing in the opposite direction.

Yes if you look at an older hose in the light you will see tiny cracks, they are caused by ozone deterioration. The cracks are usually in the outside protective layer and do not cause leaks. Tires also are affected by ozone and if you look at older tires you will see those tiny cracks, but tires are not going flat in masses from them.

If the cracking is such a problem on the V8 it would be a problem on all cars using a mechanical fuel pump, that would be 100% of cars manufactured from 1932 until fuel injection was introduced. 37 Plymouth, Cadillac V16, Corvair etc

Yes it is possible to spend thousands to get tot he correct repair but it can be avoided. Using a pressure/vacuum gauge ( about $15) will diagnose the fuel delivery system.

The problem described is a common one most often blamed on "drain back" (which is impossible)
It is a non-functioning accelerator pump and/or choke adjustment.

Moisture (or moist air-and to a fuel system, these are pretty much the same thing) entering the fuel system via perforations in a flex hose can and has traveled in both directions. This was indeed proved on the factory level in an OEM warranty test using dyes... which ended up traveling rearward to the tank and upward to the carburetor. I know because I oversaw the lab tests at the OEM and it certainly very well did happen.

While I never did lab tests on a Packard we did prove this same possibility many years ago with a troublesome hard-starting 1956 Patrician with factory air... and with a 1966 Cadillac. Both issues occurred during winter in Los Angeles. Both vehicles turned out to also have perforated diaphragms in the fuel pump (this indeed was also confirmed by a company in LA that rebuilt the fuel pumps). Once the moisture got into the system, it did not care which direction it went with the engine off, although obviously with a good fuel pump everything would want to move in the direction of the engine.

In these cases, moisture is usually cumulative-not a one-shot deal. And yes, it could happen on any car with a perforated flex line in the fuel system and a weak or perforated diaphragm in the fuel pump.

And while we can always talk on a basis of "if this, then that" and "if one, then 100% must also be true." But like with smoking cigarettes and getting cancer, this is not an issue that always occurs on a one-to-one basis. There are probably lots of Packards (and other cars) out there still operating without their owners realizing that occasional or habitual hard start is due to a perforated flex line at the fuel pump. Just know I have indeed seen this issue in Packard V8s... and learned it many years ago from a friend who had fleets of these cars over many years, AND...I proved this again at a Packard meet just a few years ago when a fellow's Packard V8 would not start for lack of gas. Told the owner to check the line when his car started after a priming (even when he insisted the flex hose was good). Wanna guess what he came running up to show me? All the little cracks in the hose when it was bent in the light. Wow. Shocking!

And yes, a weak accelerator pump in a carburetor can indeed cause hard starting (so can other things too). It also can-and has existed instead of OR along with a perforated flex line off of the fuel pump or in the fuel line. Seen a jillion of these in Southern California over the years. The dry-rot condition is also known as "smog rot" and have seen it even on beautiful-looking flex hoses. Even N.O.S. ones.

Either way, this is not the issue here. The point originally made was if I am having a hard starting V8 Packard that appears to be having leak-down issues... AND that engine indeed starts and runs after being primed with fuel, do I want to start in rebuilding carburetors and doing other complicated, expensive remedies and mojoe? OR do I simply want to check that flex hose for rot and replace it first? I put my vote for the quick, easy, reasonably inexpensive first. THEN go to the other remedies. As with many systems, it is often cheaper and easier to look for and remedy the root cause rather than repairing myriad symptoms.

A thought and take it for what it is. Fuel cannot drain back (meaning back down past the float bowl to the pump and then to flex hose)The fuel can only stay in the bowl. So the only possibilities are:

1) A porous float bowl casting ( which you would physically see)
2) Bad or weak accelerator pump
3) Choke issues
4) Weak spark

Thanks
James

Also on moisture entering the fuel system. Unfortunately that will always be an issue because a carbureted system is a open vented system. Unlike new cars with fuel injections that have closed ( to the atmosphere )systems due to gas recirculation for cleaning burning emissions.

James