1953 Dodge M37 military fuel problem?

Yesterday I used my truck to run a small errand about 3 miles. I thought that two thirds into the ride I might have heard some very
slight back fires but the truck is very loud anyway so it is really hard to tell sometimes when you're driving. The performance didn't seem to falter though. I got to where I was going, picked up the load and started the truck up. It ran fine until I got it on the road. It sputtered and surged and did this intermittently all the way home. I made it into my driveway, blocking everything else, where it stalled and with repeated cranking would not start up again. I didn't smell gas so it didn't seem to be flooding. The carburetor air intake in these trucks has a special "S" shaped elbow with a trap in it for attaching a fording pipe. I've never done this but this arrangement makes it impossible to prime the engine with gas. I tried shooting starting fluid down the pipe a few times but each time there wasn't even a "kick". I waited about 15 minutes and finally in desperation shot a big load of starting fluid into the intake To my surprise it started up and ran pretty well. I backed it into its spot and checked it over. The gas gauge showed at least half a tank and the engine was running pretty well with only an occasional slight miss. The only thing I did find was that the engine was running a little rich. (A slight adjustment of the mixture screw on the carburetor sped the engine up I'm guessing a couple of hundred RPM's), after which there was a definite improvement. It doesn't seem like a slight mixture mis adjustment could have all of a sudden caused this problem because I wasn't smelling any gas? I've dumped both alcohol and fuel system cleaner down the tank as a precaution but I'm really at a loss for what might be going on here. If anyone has any Ideas I would be very grateful. Lenny
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On Thu, 28 Jul 2011 06:27:30 -0700, klem kedidelhopper wrote:

When was the last time the tank was cleaned/replaced?
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Could be some crud in the gas tank and fuel filter. cuhulin
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On Thu, 28 Jul 2011 12:29:53 -0500, J R wrote:

JR...?
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Had to hop on Windows Live ID for WebTV.That's why the J R.
Who shot J R? cuhulin
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klem kedidelhopper wrote:

Vapor Lock? That's a standard scenario. Runs, gets herky-jerky, quits, <wait a while>, runs again. Look for fuel lines near hot stuff. Especially steel ones.
Or not...just my $.02
--
John Gilman
snipped-for-privacy@xxxReMoVexxxemail.com
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An old ''Trick'' for vapor lock is to wrap some wire around the fuel line to help radiate heat off/away from the fuel line.Sort of a heat sink, per se. cuhulin
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We used aluminum foil, and it CAN help in some cases.
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Perhaps it was aluminum foil I was thinking of.Borrow a roll of it from the kitchen and have at it. cuhulin
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J R wrote:

How is that going to help if the problem is the fuel line is absorbing too much heat from nearby hot components?
If you insulate the fuel line in the neighborhood of hot components the fuel will stay cool. The fuel in the fuel tank should be cool enough and the fuel in the line will stay cool as long as the parts of the metal fuel line that are near things like exhaust manifold, radiator hoses or engine block. Even the hot air flow from the radiator on a hot day can add a lot of heat to a metal fuel line. Modern fuels have lower vapor pressure than years ago so vapor lock is more of a problem with carburetors than it used to be.
-jim
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Luckily, no modern vehicles that I know of use carburetors.
In those older units that do, you can shield the fuel lines from heat sources and that will often buy you some relief. What you use to shield the line is up to you, your finances, and your inventiveness.
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hls wrote:

You might actually try reading the thread (or at least read the title of the thread) you are contributing to. A 1953 Dodge is not a modern vehicle.

Plumbing Insulation costs pennies per foot.
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I did read the thread, asshole. Try thinking... Not many people drive old military vehicles nowadays. And there is not much of a problem with FI vehicles.


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hls wrote:

You wrote:
" We used aluminum foil, and it CAN help in some cases."
That was bad advice, no matter what you now are trying to turn it into.

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I thought of vapor lock but I'm just curious though, I've had this truck 27 years and never have experienced this problem. I've also run it on much hotter days than it was the other day this problem started without incident. This issue with the gas that affects older vehicles, is this a recent issue ie: the last year or so or is this since the leaded gas was abolished? This truck was designed to run on 70 octane but would using an "octane booster" be of any benefit? Or perhaps high test gas in the Summer months? I also meant to mention that I use lead substitute with every fill up and there is also something else I do regularly. I dump a quart of ATF in the gas tank with most fill ups too. A mechanic friend old me many years ago this helps provide upper cylinder lubrication. And without a catalytic converter I don't have to worry about the oil damaging it. Lenny
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Back in the 1980s, a friend had an old Dodge Power Wagon he offered to sell to me for $700.00.It was in OK running condition and had a decent body on it.I don't know why I didn't buy it. http://www.dodgepowerwagons.com
There is a lot of room under the hood of those old vehicles.You could add on to the fuel line (assuming vapor lock might be the problem?) and reroute the fuel line away from heat sources. cuhulin
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On Jul 29, 11:25 am, snipped-for-privacy@webtv.net (J R) wrote:

om

The other day since the incident, I had to move the truck and it started right up and ran better than it has in a long time, Of course the engine wasn't hot at the time. (You may also recall me saying that I adjusted the mixture screw on the carb. the other day after I finally got it started). That would not account for the no fuel smell during repeated cranking earlier but I don't know. I didn't pull a plug wire at the time but I just have a feeling its not ignition related. And getting into the distributor on these is no easy matter either. So I'm going to fill up the tank and see what happens around town, (short trips). He wouldn't be very happy about it but we have plenty of chains and my son can tow me home if we have another incident......Lenny
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On Jul 29, 11:25 am, snipped-for-privacy@webtv.net (J R) wrote:

om

Well I got brave and took a ten mile trip in the truck this evening. The other day after the incident happened I added some alcohol, octane booster, and carb cleaner to the gas tank. I also leaned up the mixture as well. It appears that it was running a little rich. The truck actually ran better than it has in a long time. I had my son with his flat bed on standby just in case but luckily never had to call him. Was the whole thing just a fluke? It just seems very strange. So I'm not convinced that everything is OK until I get some more time on it over the next few weeks. I guess we'll have to see what happens. Thanks for all the advice. I really appreciated it. Lenny
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klem kedidelhopper wrote:

Vapor lock was a wild guess based on the very little information you supplied. It roughly fits the symptoms, but then so does a lot of other things. I would suggest doing a complete tune-up. New Points, new plugs (or at least a good cleaning) and adjust the valves. If that doesn't correct the engine misfire then you need to dig deeper.
-jim
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I'd check/ change your fuel filter, and maybe check to see if your carb might need a rebuild.. How's the fuel pump pumping???
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