Fuel System: hard starts when hot

[thom]

Our '52 V8 Commander is hard to start when hot. First start every day is fine, but on restart it has to spin and spin before starting. It spins great, having a freshly rebuilt starter, and being converted to 12 volts, but I suppose it's vapor locking.
Other than adding an electric fuel pump what can I do to help the problem? Thanks.

[Greenstude]

Is your car being fed ethanol-contaminated fuel, or the pure stuff? When my '47 Champion was refueled in Maine (where non-ethanol fuel could not be found) it was extremely hard to start when hot. It stalled at the slightest excuse. (Just ask the people lined up behind me at a traffic light in Bangor on a Sunday evening!) Once I got back to New Brunswick and refueled with non-ethanol, the symptoms immediately went away.

As you say, vapour locking is also possible.

[Jeffry Cassel]

Indeed. Vapor pressure of the crap our all-seeing and all knowing govt forces on us is lower than a snakes belly in a wagon rut. But it really saves fuel as it only takes 1 1/2 gal of fuel to make one gal of alcohol.

[thom]

Anybody on here tried the method shown on Youtube to remove the alcohol by mixing one gallon of water with ten gallons of gas-ahol then allowing the water to settle to the bottom, water being heavier than gasoline, taking the alcohol with it, then draining off the water leaving alcohol free gas? I understand it lowers the octane rating a smidge so some octane boost should be added after the removal process.
I think I'll try a tank or two of 100% gas in the Commander and see if the problem goes away. I'll let you all know.

[BobWaitz]

Good Lord, please don't try that. That is right up there with eating Tide pods!

What finally fixed my problem was a spacer under the carb and advancing the timing a few degrees. Starts up hot just fine.

[RadioRoy]

What happens if you loosen the wing nut on the top of the air cleaner and dribble a shot glass or two of fuel down into the carburetor? Will it start then?

[doofus]

Thom, years ago i saved a couple of bakelite 2 bbl carb spacers. i have 1 left, if you want to try it PM me. Luck Doofus

[thom]

It's not quite as simple as that to dribble a little gas in the carb on mine. The air cleaner is a overhang style, the wingnut being over above the RH valvecover and a screwdriver needed to loosen the clamp around the air horn of the carb. So I have not removed the air cleaner when experiencing a no start situation.
My car has a metal line from the tank to within about 12" of the fuel pump, then a clear plastic fuel filter, 3 or 4" of rubber line, the stock pump, about 8" of rubber line, then the the carb. I don't know what to change there to help the problem. I have an electric pump but I'd rather not install it unless I have to.

[Mrs K Corbin]

I'm probably nuts for admitting this....
I fought the same problem for over a year and was having to dribble gas down the carb to make my 2R5 start.
I finally found the problem. Even though the choke cable came all the way out on the dash, and moved on the outside of the carb,
the choke wouldn't completely close on the inside.
After fixing that, it doesn't take too much to start now.

Check your choke as part of the process, not just on the outside, but look down the throat of the carb to make sure it closes.

[my2R5]

What finally fixed my problem was a spacer under the carb and advancing the timing a few degrees. Starts up hot just fine.

What was the thickness of the spacer?

[Eric W]

My car has the same problem - same car & engine as well. '52 Commander. I haven't converted voltage, and the starter could probably do with a rebuild. But I did add an inline electric pump. The pump is on the frame, as far back as I could get it, so it will have liquid gas to push regardless of what's being vaporized further forwards. Running this pump for a while, it eventually cools things off up front enough to maintain liquid gas in the carb, allowing the restart.

There was an article about this in this month's Turning Wheels. Their suggestions are:
1. Cranking - may need new battery, cables, or starter rebuild.
2. Engine temp - remove flaps in fender wells to let cooling air out, ensure all shrouds on air inlet side are in place so cooling air isn't escaping. They also mention 160 deg. thermostat, which I believe is dubious, because when the engine sits & heat soaks, it's going to get as hot as it gets, regardless of the thermostat. Also this cooling air business doesn't matter while it's parked - other than opening the hood.
3. Tank to pump hoses/tubes in good condition - to avoid a restriction in the line preventing good flow of liquid gas.
4. Fuel pump to carb - consider insulating this line. They suggest DEI Cool Tube or Cool Wrap. I found this for about $17-25 for a 3' length. Reviews are mixed. Phenolic spacer under the carb to possibly reduce heat-soaking of the carb itself. At steady-state though (after being driven then parked for a while), the carb is going to get as hot as it gets anyway - insulation just slows heat transfer, it doesn't stop it.
5. Weak fuel pump.
6. Ethanol-free gas, if possible.
They go on to mention possible addition of a return-to-tank line past the carb. I guess this would be to create a continuously-circulating system, but you might also create a system that just gets the gas in your tank hotter & hotter as you drive...
And they say as a final idea - add the electric fuel pump as far back as possible, and run this to push liquid gas up to the carb. The pump that I have doesn't need to be running all the time. Once the engine is started, I can turn it off & the gas is just drawn through with the engine-driven pump.

Next things that I'll try are insulating the fuel line as it passes above the engine, and the spacer under the carb. I'll just make my own. Oh, and opening the hood. I don't think real gas is an option around here anymore.

[Greenstude]

You mention rubber sections in your fuel line. Either old age or ethanol could have destroyed (swelled) the inside of the line without being obvious on the outside. But, then the engine always should be hard to start and run.

[JoeHall]

I believe the vapor lock is more related to 1940s-60s fuel systems and metallurgy than to, "modern gas". As a high schooler in the 1960s, I worked on farms every summer, in hay and tobacco. Hay work included picking each (rectangular) bale up in the field, and tossing it onto a slow moving truck as it crept by, where another worker would stack it. The hay hauling trucks were 1940s-1960s vintage flat bed, 2-4 ton, with six cylinder motor. We'd start at daylight, then break for a 30-45 minute lunch around noon.

After lunch, we'd all be hoping the hay trucks would start, and each had about a 50/50 chance. Under the hood, most trucks would have 10-20 clothes pins, and tin foil on the lines. If we could get just one truck to start, we'd work with that one, and come back and try the other(s) later, often several times. Most times, we'd eventually get them all running again. Also, there was a 1957/58 S-P Tech Bulletin on alleviating vapor lock on supercharged Studes/Packards. So I believe the problem is more related to technology of that era than anything else. For us still trying to keep them running 50-60 years later, modern gas probably does not help. But the problem was around long before today's gas.

[JoeHall]

As for alleviating vapor lock, there's usually not a single thing you can do, but several things combined will help quite a bit: First and foremost is an electric fuel pump; lines insulated and routed as far away from heat as possible; a fuel return one; insulator/spacer below the carb; replace the automatic choke with a manual choke; wire open or remove the heat riser valve; install a max capacity radiator; max flow fan on the motor, and pusher fan in front of the radiator. If AC equipped, only use the AC when the car is moving.

If you want to ELIMINATE vapor lock, install EFI, but must include a fuel return line, as that is how heat is transferred away from the hot engine bay.

[gjamesk]

4. Fuel pump to carb - consider insulating this line. They suggest DEI Cool Tube or Cool Wrap. I found this for about $17-25 for a 3' length. Reviews are mixed.

FWIW, On my 52 Commander, I used the DEI sleeving to insulate the metal fuel line where it comes up along the radiator to the fuel pump and from the fuel pump to carb. Can't definitively say it helps or not, but I have not experienced vapor lock driving in Phoenix this summer in 100+ temps. This is using regular pump gas and adding Stabil 360 stabilizer.