Packard Forum Index » V-8 (1955-56)

Hi all,

Today I drove the 400 over to a friend's shop as I left it there for a fellow to come by and give me an estimate on the trunk. While in route, I fueled and then drove about 10 miles. It was easily 106 degrees outside and when I was about 1/2 mile from my destination the 400 began to choke and sputter like she was out of gas? I hit the switch to the electric fuel pump I'd previously placed in line and I was able to continue.

Once at the shop, I used my pal's snap-on laser temp reader and determined that my steel fuel line leading upward from the mechanical fuel pump had a reading of NLT 175 degrees!

I didn't put any asbestos or anything else on the line when I ran it from the pump to the carb. Could the steel line be too close to the block? Should I have more clearance to promote more 'air-flow' around the line? My pal said many older cars were notorious for vapor-locking?

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106 F.! Now that is HOT! Don't know if it would make any difference but the routing of the steel fuel line is different from what I've seen, at least on the Caribs. It goes more or less straight up from the pump (without the double bend), on the outside of the water manifold, and makes a gentle curve, passing adjacent to the bottom forward edge of the rocker cover (with a clip) and then on to the carburetors. That routing gives it a bit more exposure to the fan blast though I don't know that it would be enough to make a difference, try it and see I guess.

Guess you already know that's not an OEM-style fuel pump. Also the rubber fuel line is available from a PAC region with OEM-style brass threaded fittings on the ends. But I doubt either of those have anything to do with the problem.

As O_D says, the Caribbean goes straight up and bends in but that is probably because the filter is further forward for the dual carbs. The training book "Know the 55th series" has a half shot showing the pump. The line is similar but still appears to hug the block.

What about some kind of heat protection. McMaster-Carr has some sleeving products which look like they might protect and not look out of place--one even looks a lot like the material on the choke heat tube. Some are full tubes that the pipe would have to be removed to install, others are wrap around and could be installed in place. If that is something to consider, do a search for pipe sleeve and select the sleeves on menu that comes up.

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I'm surprised that the Carib has a clip on the line between the pump and carb.

KevinAZ. Make sure that hte line is not touching any part of the engine between the pump and carb. Try running without the air cleaner on the carb.

I had some minor stumbling problems last year in hot weather with my Executive. Usualy only after setting for 5 or 10 minutes (engine off) and 2 miles of stop and go down the road.

Drove Thursday about 80 miles in 95 degree weather and no problems even with air filter in place and this time alot of stop and go (engine on/engine off). Most likely the vapour lock we are experienceing has to do with gas formulation.

But then again, my 88 Ranger (carb and mechanical pump) shows no symptoms whatsoever and it is often parked and ideling with AC on in a low lieing almost bowl like paved lot for sometimes up to 20 minutes.

IIRC it was HH56 that mentioned somekind of electric cool sink that is rather small. I don;t remeber the name of it. I believe if one of those were attached to the outside of the carb bowl to keep it cool then would likely solve the problem.
I am more suspect that gas is vapourizeing in the carb bowl than in the line. BECAUSE, the vapor lock symptom seems to come and go so fast as to only create irratating stumbles of the engine in my case only last year.

KevinAZ. Watch the fuel filter when the engine is shut off after a hot run. About 3 minutes after the engine is off i noticed that hte fuel in the filter began to vanish at a rather fast rate, about 15 seconds. THEN refilled itself about 2 minutes later and it only took about 15 seconds to refill.

See if that happens to your car after engine is turned off after a hot run.

Maybe put one of those "Cool Sink" things on the pump too.

It's called a Peltier elementen.wikipedia.org/wiki/Thermoelectric_cooling but not sure it would be efficient enough--plus needs some engineering. This might be a good application for strapping the pipe to the AC suction line JW mentionedpackardinfo.com/xoops/html/modules/newbb ... ic.php?post_id=53305#forumpost53305 to take advantage of that free cooling.

HH56, in your pix from the training manual, note that the steel line also goes outboard of the water manifold branch. Again, I doubt it's critical with respect to the problem.

The picture in the service manual also matches the one that Howard posted and shows the fuel running basically straight up on the outside of the motor hovering about an inch off the block. I think where you have the line running between the block and the water manifold is the problem. That area has got to be over 150+ degrees with the motor at temp. You really want as much distance between the fuel line and the block as possible.

Worst come to worst, you can use a sleeve insulator like this:

summitracing.com/parts/DEI%2D010403?autofilter=1&part=DEI%2D010403&N=700+400384+115&autoview=sku

From what I can see, they are basically the same except his is bent inward close to block lower down next to pump.

As the other pictures show, the filter is close to engine center. To get there, they seem to be going through about a two inch offset gap between the water manifold pipes. Lower pipe is close in as the pictures show and the upper one sticks out leaving a space the fuel line goes thru before bending into filter. On the Carribean, the filter is way in front and almost directly above the pump.

Maybe someone else with a single carb could see how their pipe routes. There are 5 different tubes listed for 55-6 probably due to length needed for various carbs. Caribbean seems to be only model using the same both years.