Pulse jet problems

[Mathias]

I wrote something about my pulse jet last week and this weekend my pulsejet run but under air suply. My pulsejet starts to run but then I can't stop the air suply with some pressure, over the flowinjector. I think I need more gasoline to run the pulsejet!!!!

[Mark]

I wrote something about my pulse jet last week and this weekend my pulsejet run but under air suply. My pulsejet starts to run but then I can't stop the air suply with some pressure, over the flowinjector. I think I need more gasoline to run the pulsejet!!!!

If that is the case, watch the fuel line if you have the kind that you can see the fuel level, and watch how the fuel level fluctuates when you blast in some air. Sometimes, if you are angled off the mark, it will push the fuel back down in the line and other times it will draw the fuel in. Use a larger fuel line if you think it isn't getting enough gas. And get it running soon!
Mark

[Mathias]

Dear Mark,
always when I start my pulse jet it starts to run but then some air comes out from the venturi and stops, are my pulsejet valves to small ???

[Mark]

Dear Mark,
always when I start my pulse jet it starts to run but then some air comes out from the venturi and stops, are my pulsejet valves to small ???

It's really hard to say what could be the matter without seeing what you are working with. Maybe your valves aren't getting closed fast enough and letting the feedback bleed away, losing the rhythm. Maybe your valve retainer is letting the valves swing open too far. When valves swing open too far, you will often get gunshot noises without the teasing, false start stuccatos.
It could be that your valves are too small too as you say. Forced air will create the effect of more valve area and allow the jet to "run" when otherwise it wouldn't.
Have you tried blowing into the front of your jet with your mouth, like a horn. It isn't written in stone, but if it isn't resonating then perhaps your reeds are lacking something. Sometimes a non-resonating reed will resonate beautifully if you give the reeds a longer or shorter body jet which matches its characteristics.
Mark

[larry cottrill]

Mathias -

Another thing that can affect good starting and running is the centering of the reeds over the holes. MAKE SURE your reeds are EXACTLY centered on the holes. Also, make sure that they lie perfectly flat against the valve plate surface. The valve plate MUST be flat, smooth and clean for good valving.

L Cottrill
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