Packard Forum Index » Pre-War (1899-1942)

This car starts great when cold. So far the carburator has been rebuilt, an Auxillary electric fuel pump was added to the fuel system. Added two 6 volt Optima batteries in parallel and replaced all the battery cables.

Car reluctantly starts when warm (within 5 minutes of shutdown) about 50% of the time and requires at least one pump of the gas pedal when it does start. If the car sets 20 minutes, no problem.

Could this be a timing issue? Too much advance? Choke is working as intended and is in the open position when warm.
Should we replace the coil snd condensor?

Any advice is appreciated.

Thanks
Rob Troxel

Percolation in the carb?

That's a thought Big Kev. Used the proper mounting gaskets.

How would you determine if peculation is the issue?

Just wondering if after you shut the motor off the heat soak is causing the fuel to boil a bit and basically "flooding" the engine, causing the hard starting issue you are seeing.

I'm not a carb expert by any means, so take a look in the service manual or numerous carb manuals that are here on the website.

Also do you have the correct insulators under the carb and all (if any) factory heat shields in place?

I am sure someone more familiar with the Pre-War setups should be along shortly to help you.

Easy enough to eliminate the timing question, just set the timing. Might be ignition; failing condensors (and coils too for that matter) tend to show failure when hot, and seem OK when cooler.

But I'd guess it's flooding. What happens in you engage the choke unloader while trying to start? First I'd suspect either a improperly set antipercolator valve if your carb uses that, or if not then perhaps a clogged fuel bowl vent. After that my primary candidates would be leaking needle and seat, too high a fuel level in the bowl, or a defective (sunken) float - though all of these would show symptoms of a rich mixture during ordinary driving (sooty plugs, sooty tail pipe). Why not pull a spark plug and look for telltake signs, or show us a picture?

G'day Rob,
to PackardInfo. I invite you to include your '40 120 Convertible in the Packard Owner's Registry here on PackardInfo.

Is heat riser working properly or at least wired open? Is the gas line routed away from exhaust manifold? I think you must first determine whether problem is fuel or ignition related, then attack problem.

Thanks for all the input so far. We are getting the timing checked, putting on a new coil and condensor, putting in new plugs too. The fuel ine seems to be sufficently away from the exhaust manifold though I think we might add an insulation jacket ion the line for good measure. I'll check the heat riser though I don't recall seeing it before.

Dear Rob:

Okay the carburetor is good, and it has plenty of gas. Given 1940 is a Carter unit main jet boiling should not be a problem.

The manual states the correct way to start the car when hot is to floorboard the gas pedal and crank until it starts. In other places Packard explicitly stated that extended cranking occasionally will be required.

To isolate the problem you can buy a spark tester from NAPA and check the ignition when hot. It should easily produce in excess of 20kv.

Next is a compression test. You should have at least 100psi for easy starting when hot.

Tim,

Thanks..will do and report back.

RT