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

On hot days car stops and after ~45min will restart. I have tried wrapping fuel line with reflective tape. Car has electric fuel pump.

Has anyone else experienced this problem? Suggestions

I don't mean to be non-responsive in detail, but this is probably one of the most frequently posted topics on old car websites - there's a current one going on AACA about vapor locking with a late prewar Buick, many others as well, and quite a few on this site.

Might I suggest you use the search capability and browse what's already been said - I don't think there are really any "new" solutions that haven't been posted many times before.

Sorry if I'm coming across as abrupt, just that so much has been said before. Give it a shot and let us know if you find sufficient suggestions, and if not, then we'll go from there.

What is a bit unique-3 Packards-2 straight 8's and the V12. Having problem with only the V12. The usual fix is an electric fuel pump which it seems has not fixed the problem. Is there something unique to a 12? Wrapping the fuel line is another fix-so far that has not helped. Mixing kerosene in the gas has not been tried-is there any harm in that?

Check the gas cap VENT and the carburetor vent.

Just out of curiosity did any of your Packards belong to the late Judge Tom S. of Nashville??? Or maybe Motlow???

A couple of questions and a couple of thoughts:

What part of the country are you in, or what are the temperatures at which your problem is encountered?

What kind of driving conditions bring ont he problem?

Where in the fuel delivery system is the electric pump located?

What's the pressure of the pump?

What's the coolant temperature when the problem arises?

Are you pushing thru the mechanical pump or is it bypassed?

Is the electric pump plumbed with a return line?

Excellent suggestion about the gas cap vent!

My experience with Twelves is fairly limited, but I think generally they are not particularly prone to vapor lock. Have you eliminated a bad (or bad set) of condensors or ignition coils - symptoms have some similarities are are occasionally confused with each other.

Vapor lock (if that's the problem) is much more likely to occur in the suction side of the system because the boiling point of the fuel is depressed on the suction side, and elevated on the pressure side. Any close proximity of the fuel suction line to the exhaust system?

Someone told me about the old clothespin on the metal line to the carb trick...it sounds like an old wives tale, but if the line was hot maybe it acts like a heatsink?

Any actual truth to that helping with vaporlock?

Another myth. Just think about how efficient a conductor of heat a piece of wood is.

I agree, you'd think some copper line or aluminum would work better.

Also, when i vapor-lock, the line is decently cool.

Lastly, nothing easy and cheap ever seems to be the correct fix. :-/

Dear Packard1949:

The Packard manual lists vapor lock as a cause of hot starting problems, but does not elaborate. The electric pump should remove vapor lock as an issue, but to test get the car hot, let it heat soak to the no start condition, turn the pump on, and pump the throttle. Fuel should begin to spill out of the anti-flood.

Next get a KD spark tester from NAPA and verify a good hot spark of at least 20K.

Third pull the plugs and perform a compression test.

If the above is all good then look for clogged main jet air bleeds in the Stromberg EE3. This will manifest as gas running out of the anti-flood when parked.

Don't forget that proper hot starting procedure is to hold the throttle to the floor when cranking.

Good luck with your V-12. When new they usually started faster than a computer controlled motor hot or cold. However, the manual does state that occasional extended cranking may be required to start a very hot motor.

Oh, and one other point is starter cranking speed. If your motor is not turning over fast you should consider a complete set of custom made battery cables from RI. These can make a world of improvement and save your starter motor as well. Use 3/8 anti-shake washers at all chassis connections.