iGX800 not bypassing

I upgraded to the iGX800 with CAT pump. Everything was fine for a while, but it won’t bypass back to the water tank when you release the trigger. We have replaced just about everything except the pump and engine. We even went to a larger diameter bypass hose and fittings. In idle mode, the engine/pump pulses water into the pressure washing hoses. My hoses are blowing out within weeks instead of months and is starting to cost a small fortune. The local shop is stumped and can only offer to sell me thicker hoses, but this doesn’t address the real problem here. Any ideas?

What unloader are you running on this setup?

ZK73 Unloader with #2 Bypass Orifice. We run a hose from the pump to the unloader mounted on the rail of the trailer. Working pressure is perfect.

What happened when you tried another unloader?

Nothing changed, that’s when we put in a larger bypass hose and fittings. That didn’t help either.

Are you able to post some pictures of the unloader and the pump ?

He’s using a crap unloader. Try a YU21405 and I think your problem will go away. And find another shop to go to


Does that unloader hook into the pump? or is it mounted on the side rail like mine?

It’s just an unloader, it mounts wherever you want it to be. But, the side rail where you have it is ideal

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You have a flow sensitive unloader.
I don’t see 3 connectuon to it.

Here’s another angle.
I’m going to order the other unloaded mentioned earlier and see what that does.

Not sure if will make a difference but put your unloader strait. Now it sits at a 90 degrees angle.

Go to a ZK1 unloader. Can use about anything for a bypass hose and a lot more forgiving.

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Finally got the new unloader and installed today. Bypass works perfectly. I noticed the water going back to the tank before I had a chance to adjust the pressure. Got everything dialed in and had a blast cleaning that first driveway.

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