Engine dies as it gets hotter.

[kubelwagener]

Am having an issue with my newly-acquired Thing. Before I start the process of source elimination, any ideas on what the problem might be, from those of you are experienced?
The engine runs nice-- until it's been run for a while (about 3 to 5 minutes of driving/engine running). Then, it dies. Regardless of whether vehicle is stationary or on the road.
At first, thought the problem was leaky intake seals, causing engine to suck air. Replaced them, problem persists.
What are problems that only crop up as engine gets hotter, but not when cold? Fuel pump? Carb maybe?

[74 Thing]

How long does it take to restart?

Maybe carb adjustment, intake leak, fuel pump, hot fuel line, non vented gas tank, fuel pump flange pinching the fuel pump pushrod as tjhe engine heats and expands...

[kubelwagener]

It runs fine again after it cools, maybe 10 to 20 minutes.
Intake leak-- meaning an air leak at another seal?
non vented gas tank-- meaning I should try it again maybe with gas cap off or loose?
hot fuel line-- causing vapor lock, maybe?
fuel pump issues-- I'm not too familiar with it yet, will need to study up on it.
Thanks for your input!

[mondshine]

The first thing I would do is remove the gas cap. If you notice air rushing into the tank, look for a clogged tank vent.

Is there fuel in the carburetor bowl?
When the problem occurs, you can remove the fuel hose from the carburetor, and check fuel pump output with the hose end in a jar, and the engine cranking. It's best to do this with help, so you can keep an eye on things to avoid a catastrophic fire.

Before you take the top off of the carburetor, you can pour a couple of ounces of gasoline into the bowl vent with a tiny funnel. If the engine runs normally at this point, you can look for fuel delivery problems. Take off the top of the carburetor, and confirm that the float and needle valve is in good order. Remove the plug at the side of the float bowl, and then the main jet; confirm that the main jet is clean.

Lastly, watch this:

Link


Good luck, Mondshine

[74 Thing]

I am assuming this is a stock engine with a 34 pict 3 carb.

Also check the cutoff valve on the carb-it should have a wire hooked to the + side of the coil and it retracts the plunger when the ignition is on. If for some reason the wire is loose or frayed this may be your problem.

Yes, intake air leak and the carb base, manifold or head to manifold mating surfaces. Spray some carb cleaner on those areas when running and if rpms pick up then you found a leak. Also, you can use a short piece of vacuum hose as a stethascope and listen for air leaks.

You need to adjust the carb per the manual with the engine at operating temp.

Vapor lock may be a problem-pull the gas hose and put it into a bottle when this happens and have someone crank the engine and see if there is fuel pumping out.

I bet it is the gas tank is not vented. When this happens take off the gas cap. If you hear a swoosh sound then the gas tank is not vented properly and it is causing suction.

[germanbilly]

What type of ignition system do you have. Had a problem with mine with the electronic ignition went back to points and have had no problems since.
GB

[kubelwagener]

Thanks guys for all your input!
Unfortunately it's been a tough work week so only got to confirm one thing-- that it has nothing to do with the fuel tank--- there is no sudden intake of air when I remove the cap, nor does the problem go away even with the gas cap off. It runs beautifully for about 2 or 3 minutes, then cuts off. Then after a 10 to 20 minute rest it easily restarts and does the same thing.
In the next couple of weeks will be implementing your further suggestions and will update you. Again, thanks!!

David

[gears]

I have seen similar symptoms caused by valves that are too tight.
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[doublecanister]

when it "cuts off",

is it a slow sputter then die or does it "cut off" like turning the key to off?

Gears mentioned valves being to tight, although I've not heard that one before, i'm sure its a possibility. I'll keep that one in mind for later.

But, my 2cents, i'm leaning on it being an electrical issue.
Points, or condenser or "whatever ignition" you have, but that's a guess.

if you had a infrared thermometer you may can find a hot part. Depends on where it is/what it is.

But the reason I mention this is in my muckings with the electrics on my old 51 Ford, I made a 12v to 6v device that when it got too many amps thru it, it shut down and got rather hot. Instant off.

I also read a post a while back, where the guys condenser ended up being the issue, sounds "kinda" similar but Anyways, I AM guessing here so please let us know what ya find.

In my case on the 73 Vw, my anti diesel solenoid was sticking, I could drive but coming to a stop sign it'd cut off.

Not exactly like your symptoms, but anyway....

Hope it's quick and easy too!

T
_________________
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2020 - Mustang Eco Boost [High Performance]
1973 - Thing
1966 - Mustang GT- Fastback
1951 - Ford F1 pickup Flathead V8

[madster]