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King Quad LTF300. Can't find fuel pump vacuum port on new carb


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I'm fitting a new carb on my King Quad LTF300. From China. Only one I could find in UK. I think it should have 2 vacuum ports.

The vacuum port for the petcock is silver coloured. I can feel the pulsing vacuum. Putting the tube to the petcock there operates the petcock100% perfectly.

I can't identify the vacuum port for the fuel pump. The new carb is identical to the old EXCEPT that in what I think is the 2nd old fuel vacuum position is a brass upright port with a very small hole. When running, there is no vacuum I can feel and putting the fuel pump vacuum line there does not give a decent fuel flow - only a small trickle.

Is this the fuel pump vacuum port - see photo?

The carb came with a silver coloured screw-ended 1.5 inch long loose port in the box. See photo. Is it intended that you unscrew the brass port somehow and put in the silver one?

I'd really appreciate your help At the moment I can only do 10mph in a stuttering fashion on the level!


Devon UK

32807720_300LTFcarcb.thumb.jpg.001f417a801ff564848d38aecdcafb77.jpg1696207756_silvertube.thumb.jpg.fac7630f710f31af9dde20c83ce7dc7f.jpgand put in the silver one?



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  • Ajmboy changed the title to King Quad LTF300. Can't find fuel pump vacuum port on new carb

You need to swap the pump ports over or drill out the new one.

They come out easy. use a spanner or pliers and turn the port and pull at the same time. Try to rotate it as little as possible because it has spiraling machining on it to help it stay in, They need a little rotating though to help them come out. Take the old one out first to see how it's done. The old one will push in firmly and be fine but if you are worried use a little loctite on it.

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No, pull the old port out of the old carby and fit it to the new carby. That other new part there is for a different type of throttle cable,

I think from memory that the spiraling machining on the ports is in a direction such that it's best to turn the port fitting anti-clockwise when you are pulling it out.  I may be wrong about that,  but I think you can tell which way is best to turn and pull if you try turning and pulling it a little each way. Pull the old one out of the old carby first. You only need to rotate it about a quarter or so of a turn. The spiral is very fast..

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No trouble.

I've pulled heaps of those and similar fittings out of carbys. They come out and go back in easily and give no trouble.

If you still have trouble with the pump. let me know and I'll post detailed instructions for testing the pump.. I have them already written up.

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