Topic: Bucking problem


silverchief    -- 05-04-2014 @ 10:04 AM
  Recently developed bucking problem with my 46 in first and second gear mild acceleration. Not there with strong acceleration in either gear, nor smooth acceleration in third. Engine is up to normal temp.
Some choke helps but situation is annoying.
Starts easily and idles smooth. Last thing done was reset float level few months ago. Since then it starts cold OK ...but does not respond to cold start choke operation as before....when it would quickly and easily move to smooth fast idle. Driven only couple of times a week short distance to coffee - mile there and mile back. Hope I don't have to reset that choke level AGAIN.


fla48    -- 05-04-2014 @ 2:22 PM
  Did you try moving the throttle adjustment to give you more throw (action) on the accelerator pump? That helped me when I had that problem.


supereal    -- 05-04-2014 @ 2:26 PM
  It is a good guess that your problem is fuel related. It could be a partially plugged fuel line, a failing fuel pump, a collapsing flex line at the firewall, or a small air leak at a connection. The change in the choke operation is the tipoff. There is plenty of fuel for starting and idling, but when the demand increases, it starves the engine. If all of this checks out, I'd pull the top of the carb to check fuel level in the bowl. If you have a plastic tipped float needle, it may be sticking.


ford38v8    -- 05-04-2014 @ 5:57 PM
  I agree with my friend Supereal, Your carburetor must maintain an exact fuel level in the bowl to function as it was designed to do. For whatever reason, that level is not being maintained, running just shy of that level. Supereal's suggestion of sucking air at the flex hose fitting or at the pump's glass bowl gasket would also be my first guess. If not driven regularly, that cork gasket mummifies and leaks. Soaking that gasket in hot motor oil will freshen it up. Just don't let your better half catch you using her sauté pan for that.

Alan


silverchief    -- 05-04-2014 @ 5:58 PM
  Thanks guys - I have an electric pump and a steel needle - but your suggestions are good and I will look at all of it and let you know.


supereal    -- 05-05-2014 @ 5:32 AM
  I had forgotten you use an electric pump, but that doesn't mean it is functioning properly. Any obstruction in the fuel line may be preventing the pump from sensing need. I have seen more than one that balks. I use them to prime the carb, but not as a substitute for the original. The Airtex pump from C&G is a good unit, but even those don't always match demand until the need is too low for even delivery.


supereal    -- 05-05-2014 @ 5:44 AM
  I had forgotten you use an electric pump, but that doesn't mean it is functioning properly. Any obstruction in the fuel line may be preventing the pump from sensing need. I have seen more than one that balks. I use them to prime the carb, but not as a substitute for the original. The Airtex pump from C&G is a good unit, but even those don't always match demand until the need is too low for even delivery.


silverchief    -- 05-05-2014 @ 1:46 PM
  I was able to tighten the clamp where the flex fuel line connects to the line from the tank, the clamps on both sides of the pressure regulator, and where the flex line connects to the carb - for noticeable improvement. Also, slightly increased the idle at normal temp, which was a little slow. So....we will see where we go from here.
Thanks again.


TomO    -- 05-06-2014 @ 6:34 AM
  Your fuel level may be on the low side as that is when the change happened.

Tom


silverchief    -- 05-06-2014 @ 12:41 PM
  Thanks Tom - seems I recall now that the bucking shows most when I am turning - indicating low fuel level in the bowl. However, I can slowly floor it in any gear on the straight - even uphill and there is no fuel starvation. Puzzling.


silverchief    -- 05-06-2014 @ 12:41 PM
  Thanks Tom - seems I recall now that the bucking shows most when I am turning - indicating low fuel level in the bowl. However, I can slowly floor it in any gear on the straight - even uphill and there is no fuel starvation. Puzzling.


supereal    -- 05-06-2014 @ 4:37 PM
  It is possible the the pickup tube in the gas tank has rotted off. Usually, that means that fuel starvation is most pronounced when turning one way over the other when the fuel sloshes away from the pickup . This causes a bubble in the line which interrupts the flow,even after the turn.


silverchief    -- 05-07-2014 @ 1:07 PM
  Thanks Bob will take a look at it.


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