1954 Roadmaster------------Is it a Buick thing that these cars will not run in cold weather? I am ready to get rid of this car as it is a daily driver but it won't drive daily. Car starts and idles great but once it's warmed up it will only runs for seconds at a time then dies- have to pump the heck out of it to start again then it only lasts for a few more seconds. Runs great during the summer. Thought there might be ice in the lines so I used some heat. The other day it ran like crap until it idled on high for almost a half hour then it was great. I'm not willing to use ten gallons of gas everyday just so it will run good. Carb has been rebuilt, fuel pump is rebuilt, all electric in ignition and charging system is new. Any remedies or ideas would be appreciated. Right now I'm thinking it's time to sell it and get rid of the head ache.

Sounds like your carburetor choke is not doing it's job. Check your car's manual or Motors Manual for correct settings for your car's carb.

Put a vucuum gauge on it and see what it reads. Then go here...Bob


http://www.secondchancegarage.com/public/186.cfm

I assume you have checked to be sure the rebuilt pump is doing it's job. The last rebuilt pump I installed was bad. Drove me crazy til I took another off another car and it worked great. It was an older rebuilt pump. Also check the filter in back of the carb. So are you saying it runs OK after it is warmed up.

Wow...

I really don't think it is your choke, but that is worth checking.

Sounds like a major vacuum leak. That makes the mixture so lean that the cold engine won't run. Idle mixture is adjustable with the screw, so you can compensate for the vacuum leak with it. But running mixture is set by the jets, pretty much fixed with a given set of jets installed.

Listen with a garden hose all around the intake manifold and the carb base for the whooshing sound of a vacuum leak while the engine idles.

Snug up carb mounting bolts and check intake manifold nuts/bolts.

Sounds like it could be carburetor icing. In cold weather moisture in the air will condense and freeze on the throttle plates and other parts in the lower carb. That is why newer cars had that large hose from an exhaust manifold to the air cleaner. Getting the heat riser in the drivers side manifold working will help. I used to spray the carb internals with WD-40 and it seemed to help keep the ice from sticking.
Willie

If the car won't run when warmed up but runs well when cold on on the choke, sounds like your warm engine carb circuits are not providing enough fuel once the choke goes off. If so, then you have a faulty carb rebuild. The easiest way to tell is to substitute a known good carburetor and see how it runs when the engine is warmed up. Clogged fuel filters and a tired fuel pump can make for the same symptoms.
Have you done a pressure and volume test on the pump once the engine is warm?
A sticky float needle in the carburetor can also cause this problem.Brass tipped float valve needles are most suspect.
Martin Lum

When I bought my 1980 Chrysler Newport used, it HAD a similar issue. As long as the carb was on fast idle, it ran well, but as soon as it came off fast idle (to base curb idle speed), it would die. I rebuilt the carb myself (the Carter BBD 2bbl, the only year they used it on a 360 rather than just 318s). I used B-12 to flush the carb venturi cluster fuel/air passages and everything looked to be good. When I started it up initially after the rebuild, it would idle . . . until all of the residual B-12 was used up, then it started to want to die again.

After much research and such, I got a bent-wire spark plug gap gauge and started probing the tubes in the venturi cluster (one was for idle and one was for "main system" on each throttle bore). At the bottom of the solid tubes (idle system), the "hole" down there started to enlarge with each probe from larger gauge wire (indicating a restriction from fuel additives of that 1980s time frame). I went to the hobby shop and got a selection of twist drills in the sizes I suspected I'd need.

With the venturi cluster pulled out (again!), I carefully put successively larger drills into the tube until I "got metal". I cleaned things up, shot some more B-12 to backflush any metal shavings, and reassembled things. END of problem!

This sort of thing IS NOT something that a normal (even a "professionally done") carb rebuild would address. It takes a certain amount of research on the particular carb's fuel circuits to know where to look! But if you understand how the various circuits are laid out, it's easy to find. Only thing was that the tubes appeared to be open enough (from the fact that the B-12 would spray through them (bottom to top) as it was suspected it should. Just because there if "flow" in the tube does not mean that there is ENOUGH flow for things to work right.

Each of the air bleeds and drilled orifice calibrations in a carb govern the fuel curve of the carb's different operational parameters. The section devoted to the idle circuit is just for it and the main system is similar. Openning up an air bleed leans that particular circuit out. Closing it up richens it.

The particular car did run well when it was on the main system (after warmup) and when it was on "fast idle", but warm base idle just didn't work. If you backed out of the throttle to slow down for an off-ramp, it'd die (at 55mph!). After getting the idle fuel feed tube openned up again, it did just as it was supposed to do.

Chasing these "gremlins" can be angst-inducing, but knowing how the circuits work and such will reveal where any restrictions might be which are being too restrictive (more than they were designed to be).

Just some thoughts,
NTX5467

Since It's warmed up a little today I'm going to pull the carb and go through it again and check all of the passages, then I'll double check the manual settings on the choke side. When I put it back on I'll check for any leaks. I had originally thought about the icing and the vacuum leaks (since everything shrinks when it's cold) Thanks to everyone- I'll check back with results.

By the way what carb does the car have?

One way is also to spray starter fuild around suspected vac leaks the engine will either rev up or down depending on the problem but it will show the vac leak..

Cheers
Dyna

Hi Dyna. Not trying to step on your advice but spraying starting fluid around would be EXTREMELY DANGEROUS. Starting fluid is ether and is flammable to the point of being explosive. Spraying it on or around a running engine is really begging for a disaster........Bob

"The other day it ran like crap until it idled on high for almost a half hour then it was great."

If the engine ran great after idling for a 1/2 hour, then probably the carburetor, fuel pump, ignition, etc. are in good shape!

A serious mistake (unless one lives very close to the equator) that some beginning hobbyists make is to block the heat crossover in the manifold to prevent the paint from burning off the engine. This can delay warm-up times depending on temperature for as much as an hour; and can make some older vehicles with automatic transmissions virtually undriveable for up to an hour.

If the engine has been fairly recently done, look at the heat crossover. Is the paint still there, are has it burned off?

Also, a missing, or non-functional heat riser can have the same result.

The use of deathanol can add to the problem due to its properties of less energy and a much higher heat of vaporization. The use of 10 percent deathanol will require 20 percent more heat to vaporize than gasoline. The used of 15 percent deathanol will require 30 percent more heat to vaporize than gasoline. These percentages are marginally low, as (especially with 15 percent) the carburetor must be recalibrated to flow more fuel due to the lower energy content.

As a higher percentage of deathanol may be added to boost octane, use the lowest octane fuel that does not have detonation issues.

Jon.

Yep you better be very careful!! ... you can also use water but the lowering of rpm when you hit a leak is less "visible"...

Cheers Dyna

I watched a guy literally blow his distributor cap to pieces one day when he was doing this very thing (trying to find a vacuum leak at the intake manifold and base of carb) by gently blowing propane gas out of an unlit berz-o-matic torch toward the engine, to see if he would notice the change in RPM when the engine sucked in the propane. The propane went up into the distributor cap, where the sparks jumping inside from rotor to cap ignited the explosive mixture. KA-BOOM!!! Scared us both out of our skin!

Around here a trick some guys use to inflate a tubeless tire is to squirt a shot of starting fluid into the tire, wait a few seconds for it to vaporize , and toss a match. The resulting explosion blows the tire beads unto the rim so it will take air..........Bob

My son mastered that technique. When you're off roadin on trails you let the pressures way dosn on all your tires for better creeping traction. This often results in tires breakin bead when flexed and loosing air. With folks behind you waitin for you to get goin again, it's the quickest way. Just make sure not to have anything, like little fingers etc, between the tire and rim when you toss the match.

When I first got my 1960 LeSabre the engine had never been worked on at all. However the heat crossover was totaly encrusted with black sludge and completely blocked off, probably from material sucked in through the manifold gasket on top of the engine. (The car had a terrible percolation problem at the time, and there was always a lot of gas leaking down from the carb.) I had to blast the passage clean with a sandblaster, it was too hard/solid to scrape out by hand.