Dirty gas?

[montanafordman]

Originally Posted by Onlybackroads

Ray, what's going on in Puyallup?

July 14-18 my Model A club, the Gallopin' Gertie A's will be hosting the Model A Ford Club of America national meet. There should be a good turn out with lots of fun activities. I think we are expecting/hoping somewhere in the 600-800 registrants range for attendance. I hope to see you all there!

http://2014mafcanational.org/uploads...scriptions.pdf

[Doug in NJ]

How about this?

When it acts up, pull over and simultaneously turn off the ignition and close the gas valve.
Then go and remove the lower half of the carb (held by a single bolt) and see if the fuel bowl is full or empty.

Doug

[Phil]

Like Tom said a stand up "pencil filter" in the top of the fuel valve will help a great deal. Usually what happens tho is there is a 90* turn in the gas valve under the tank! at that point very fine sediment gets clogged there fuel will flow through but at a very reduced rate and will cause the car to run lean and loose power and back fire.

When the car starts to act ugly pull over shut off the fuel valve remove sediment bowl, empty it and hang it back but leave it loose ( this is to make sure fuel does not air lock) then open the fuel foe about 3 seconds. If the bowl is not full there is a restriction in the valve. If so drain the tank through a paint filter, remove the valve, clean it install a pencil filter ( all the vendors have them) and you should be goo to go.

You can get drips out of the carb after you stop because fuel still flows through the valve and will fill the carb but not enough to run well.

[southfork]

Originally Posted by pooch

If you want to do a quick diagnosis.

Simply hook up a timing light to your coil lead and hang the light inside where you can see it while driving.

When it coughs and backfires, you see instantly whether it is spark or

Wasted a lot of time chasing a non-existent fuel problem.

Pooch, what exactly do you mean by the "coil lead"? Guess that I am not up on Model A terminology. Sounds like an excellent diagnostic procedure. Just want to get it right.

[pooch]

The spark lead from the coli to the middle dizzy cap hole.

That way you see what is happening right from the battery thru all the wiring / ignition switch/ points and condenser and coil.

Usually a timing light is just used for timing, but it is an excellent diagnostic tool for finding intermittent spark problems while driving.

You can actually drive with the light hooked up permanently if you wish....if the problem only happens once in a blue moon.

Better than pulling over with a hot engine and pulling the carby apart with risk of fire when it is 95% spark related most likely, or same with a hot engine and pulling a plug out and laying it on the head.

If the backfiring is happening, and the light is flashing normally, then you can go hunting for a fuel problem, or an electrical problem further downfield from the coil lead...ie the dizzy cap, the rotor button, or plugs.

Much easier and quicker to rule out possible trouble areas than guess elsewhere.

If you suspect an electrical problem further downfield, just hook light to a plug strip each in turn.

[Mitch//pa]

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this spark tester is much easier to use while driving hooked up with a couple long igniton wires. it also makes it easier to see weak spark as the light would be very dim.
you can also try choking the carb a little to richen up the mixture to help determine if it is a lack of fuel problem.

[Chuck Sea/Tac]

Mitch, do you have to ground one end?

[Mitch//pa]

Originally Posted by Chuck Sea/Tac

Mitch, do you have to ground one end?

Chuck,
it can be hooked up inline of the coil wire to the dist cap tower so the engine can be running, or with two longer ignition wires it can be moved up to below the windshield to be watched while actually driving. i recommend the snapon spark tester over the HF because the neon bulb is better and easier to see the spark intensity and pattern plus the HF already has a wire attached which makes it more difficult to use. everyone should have one to help with proper diagnosis of spark vs fuel problems instead of all the shot gunning that goes on all the time. here is the link to order it online directly

http://store.snapon.com/Spark-Plug-T...e-P641969.aspx