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I've had grief with my '47 EF since the day I bought it. Does yours have the SF3 Stromberg carb.? I'm about ready to find a little diesel of some kind to repower mine. Not having much better luck with my old Brockway,either,it has a bigger Continental,with down draft carb.It will at least start and run good enough to parade,but runs like shit over 10 mph.

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Sounds like either a fuel supply problem; fuel pump pressure, restriction or debris in fuel line, pin hole leaks in fuel line or connections, debris in carb or other restriction or it could be a vacuum leak which could be anywhere from the inake manifold to the wipers or maybe a vacuum brake booster if so equipped. Cool looking truck hope you can sort it out without too much aggrevation.

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  • 4 weeks later...

Running on choke makes up for one of 2 main things a vacuum leak or a clogged idle circut in the carberator between the idle mixture screws and the venturi

You can use propane to check for vacume leaks around the carb base, intake and any and all vacum ports and lines. The photo shows the propane set up I use.

Start the engine and let idle as best you can.
Open the valve of a propane torch. Do not ignite it; just open it so that a bit of propane gas can escape the tip. Propane is a "heavy gas" so it will flow in to areas you test

Run the tip of the propane torch along your intake manifold, checking for vacuum leaks in various locations such as the tubes and gaskets. Go along the entire manifold.

Listen for a change in your engine’s idling. The idling should change immediately after you pass over a leak with the tip of the propane torch. The reason the idling changes is because the engine will suck in the propane through the leak, providing the engine with more fuel.

Also check the Vacuum wiper motors, wiper switches and lines to them.

Check the Vacuum booster and lines if you ave vacuum assist brakes

Some fuel pumps also have a vacuum pump on them for wipers and such. If you do check that also. Paul

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