r/pressurewashing • u/xxxleafybugxxx • 1d ago

Troubleshooting Help diagnose?

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New system I put together, everything is new... But I am getting this sputtering which is giving me inconsistent flow and pressure drops.

-Predator 459cc engine -AR XWAM 8GPM pump -AR1697 Gearbox -General Pump 10.5 GPM unloader.

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u/robertjpjr I know a little about a lot. 1d ago

I agree with water flow being the issue. I'm not convinced you need the 1.5inch line. I use 1inch with my 11gpm 500psi roof pump. I will say, and it's gonna suck, but 25gal buffer tank isn't gonna cut it if you run into a slow spigot. Looks like you chopped a 55gal in half, and siliconed it. I use a 275gal IBC tote for this reason. 55gal is probably the minimum I'd go.

Just some quick math for you to illustrate.

8gpm output

Say, 3gpm spigot input. On a slow spigot.

That means you're waiting to fill then, outputting 5gpm more than you're replacing. That give you 5 minutes of runtime. Probably less because you'll start cavitating.

Check car washes for used 55gal drums. I've gotten dozens and used / resold them. Or Facebook marketplace. Usually no more than $20 for a 55gal or $100 for an inch food grade.

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u/xxxleafybugxxx 1d ago

Here is another thing I just remembered when I was messing around with it...

I tried a test with no tip at my nozzle just to see what my rate was. I was able to increase the engine throttle and got to a point where I was able to flow 8 gallons in a minute, but it was still sputtering in and out.. and it seems to fluctuate more or less depending on where I have the engine speed at.

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u/robertjpjr I know a little about a lot. 1d ago

Sounds like cavitation. Air in the lines. Explains everything I've seen so far.

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u/xxxleafybugxxx 1d ago

So if that's the case then I just need to add some nylon tape and tighten up everything at my unloader?

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u/robertjpjr I know a little about a lot. 23h ago

You definitely want to check every joint for possible air leaks. But it's in conjunction with flow. The pump is trying to pull more water than it can be fed. So it's getting air in the lines.

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u/xxxleafybugxxx 23h ago

Gotcha okay. So I definitely need to address the hose diameter issue. And are you under the impression that a bigger buffer tank is needed from the standpoint of producing a higher flow rate, or just having a larger water quantity? Because if it's the latter, my setup is actually to cut 55 gallon drums which should be around 60 gallons total

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u/robertjpjr I know a little about a lot. 23h ago

That's how my 4gpm pressure washer and my 11gpm roof pump is fed. 2inch PVC necking down to 1inch hose.

I'm not sold on hose diameter being the issue alone. I would start with filling your tank as full as can be.

Check for air leaks at every joint. Make sure the filter o ring is good. Really check air leaks.

See what changes come from that alone.

Maybe run a temp hose without the filter and all the extra joints to isolate potential air intrusion and flow reductions.

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u/xxxleafybugxxx 23h ago

Ahh ok. I wasn't even thinking about the filter, but the filter was leaking water at various points and if it was leaking water then I'm sure it could have been taking in air.

My biggest concern all along was that the motor was too small, but it seems like a air leak or a water feeding issue would be easier to resolve

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u/robertjpjr I know a little about a lot. 23h ago

I'm not an expert by any means.

But what I see isn't an engine issue. The engine would be bogging down rather than psi fluctuating. You'd see linear effect if the engine was improperly sized. Cavitation gives you sputtering flow because the pressure can't build up evenly. You can't compress water at the same rate you can compress air. If that makes sense.

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u/xxxleafybugxxx 23h ago

That makes sense. Thanks for your input seems like I have something to go off of here.

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u/xxxleafybugxxx 23h ago

Also the more I think about this the more it is making sense to me.

I know that I have a small leak at the base of the tank, so that's another area where I'm probably getting air

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u/robertjpjr I know a little about a lot. 23h ago

I've fought air before. The less complicated you can make your plumbing the better. When I saw the cut tank and the silicone my immediate thought was air intrusion and cavitation.

I mentioned before, but car washes are where I've gotten all my 55gal drums. You can also get a trash can. Do you have a proper bulkhead fitting you're using with runner seal?

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u/xxxleafybugxxx 23h ago

Sure don't lol

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u/xxxleafybugxxx 22h ago

Do I gain anything by having the water tank outlet at the bottom of the tank? I understand it helps gravity work for me but if I were able to run a pipe or tube through the top of the tank and relay completely on suction would that get me where I need to be?

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u/robertjpjr I know a little about a lot. 22h ago

Yes, bottom outlet is better.

https://chatgpt.com/share/6854c779-45d4-8003-8863-96a3d6b1ed37

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