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Jetter is RUNNING!!!!!!

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  • Jetter is RUNNING!!!!!!

    I picked up the Honda ignition switch today, hooked it up...and started right up. At first i was getting very little pressure so I screwed in the unloader valve. I am getting good pressure now but hte only problem is that when I squeeze the pressure washer wand(I am testing it with that first) the pressure relief valve dumps water. Shouldn't the opposite happen if anything?

  • #2
    Re: Jetter is RUNNING!!!!!!

    OK...I turned in the adjustement screw on the pressure relief valve 2 turns and now it doesn't leak when I squeeze the wand. How much belt tension should I have when the pulleys are 24" from each other? I have about 1/2" of deflection now.


    • #3
      Re: Jetter is RUNNING!!!!!!

      I just turned the psi up to around 2000 and when I squeezed the wand, the water pressure would pulse. What causes this?


      • #4
        Re: Jetter is RUNNING!!!!!!

        I forget your pump specs but lets say you have a 8GPM pump you need to be using a 8GPM pressure washer tip, like the number for a 40 degree fan will read 4008. Is the water being supplied by a tank or just a garden hose? Did you install a pulse valve on the pump or not? I usually do a 1/4" belt deflection. When I set the unloader with proper size tip installed I hold the trigger all the way then adjust my pressure up, when I get to what I want I release the triger then pull again to make sure it is stable sometimes it gets backed down a 1/4 turn or so till I find the best spot.
        Last edited by Cuda; 06-16-2010, 07:23 PM.
        Seattle Drain Service


        • #5
          Re: Jetter is RUNNING!!!!!!

          depends on your belt; the cogged ones don't need, or like a lot of tension. V-belts like on cars are like on cars. Mfr instructions are always a good place to start.

          I never deadhead my pumps. running over relief (unloader) for any length of time makes heat... probably fine and just a quirk on my part as many do it all the time... my spray wand triggers are zip-tied open.

          pumps make flow. pressure happens as a result of resistance to flow. with your wand valve closed, you should be able to dial the pressure (within reason) wherever you want with the unloader if it's plumbed right; the unloader spring tension sets the pressure and opens to dump flow above that pressure. thats why the unloader needs to be sized right; too big and no control and it chatters (that may be your pulsing), too small and it can't bypass enough to relieve all the flow

          with a nozzle, not a wand, pressure at the maifold will be dependent largely on the size of the little holes in the nozzle and how hard you've got the jetter cranked up...


          the more gpm you push through a long skinny tube (hose) with a chunk of steel with tiny holes drilled in it at the end (nozzle) the more pressure the pump has to endure to push that gpm out the system

          The unloader is a safety; if it sees enough pressure it dumps flow to relieve it.

          the rest goes out the hose and nozzle, which restricts it, creating pressure. too small a hose and no pressure left at the nozzle; it all got used up pushing through the hose. too big and no flexibility in the hose to get the nozzle where you need to. Too big of orifices at the nozzle, and no velocity there for cutting action. Too small and too much pressure created and your unloader opens up and you don't get full flow to the nozzle and no flushing action.

          in general, most all of the problems people have trouble figuring out stem from one misconception; most people are used to thinking about pumps making pressure. They don't. They make flow. Pressure just happens as a result of restriction to flow. Think about a garden hose open and flowing; how much pressure is in the hose? Now kink the end. how much pressure is upstream of the kink now? If you can wrap your head around that, most problems start to fall into focus.

          hope that helps.
          This is my reminder to myself that no good will ever come from discussing politics or religion with anyone, ever.


          • #6
            Re: Jetter is RUNNING!!!!!!

            chances are at 24hp. you need more than 1 v belt unless it's a serpentine drive belt.

            what are your engine, pump and gpm and psi specs? also pulley sizes at the pump and engine and pump rpm/ model #.

            the pulsation can be an undersized nozzle and the unloader dumping and then re-pressurizing.

            best bet is to install a high pressure tee with gage and then a high pressure valve at the end of the tee/ hose. open the valve all the way and measure flow with no restriction. then throttle down the valve to generate the max pressure on the gage. at this point direct the flow into a bucket and measure the volume for 1 minute and note the pressure. this is what's used to determine your nozzle size. post those results and you can always downsize the nozzle 1 size to account for wear and hose friction. but do this with your jetting hose so you get a true reading.

            please post your specs and some photos. sounds like it just needs some tweaking.

            phoebe it is