Not getting enough GPM, or am I?

Newbie Questions
1

I have a 4 GPM/4300 Belt Drive general pump. My house spigot gives 6 GPM. I was using my machine today and did some tests.

In one minute, I got 3.5 gallons. It took 1:40 to fill 5 gallons.

Is this normal, or should I definitely be getting AT LEAST 4 GPM? FYI, I used a new 200 foot hose today, so I’m assuming that could explain the drop in GPM?

I also did the downstream ratio test and pull 56 ounces of chem when filling up 3.5 gallons (448 ounces). Not a huge sample size but it came out to exactly 8 to 1 ratio, which I think is pretty good, right?

2

How much was your unloader bypassing?

Do you have a tach on your motor?

At the correct rpm, your pump will put out 4gpm. Some of it may get bypassed if using high pressure tips, but the pump itself will move 4gpm if it’s working correctly.

1 Like
3

I have no bypass on my direct drive 4gpm 3600psi and get about 5gpm. Is your throttle all the way up? Wish I could be more helpful lol

3 Likes
4

Throttle is all the way up. I don’t have a buffer tank yet so no bypass. Not sure what a “tach” is :smirk:

5

Disconnect the bypass hose that goes from your unloader back to your inlet fitting and plug it. Run it for a minute with the gun open and see how much water is still spraying out of your unloader.

Tach is short for tachometer.

2 Likes
6

Whoops, I mixed up the Throttle and Choke lever haha. The Throttle was NOT all the way up. My instructions for starting the Honda engine say to put the Throttle 1/3rd of the way (between the the turtle and the rabbit). And I just left it there. I assume you’re going to tell me once the engine is started and warmed up, I should be moving the Throttle all the way to max (i.e. the rabbit)? That could explain everything (sorry, I wasn’t kidding with the “newbie question” label :grinning:)

2 Likes
7

Well, there you go! Problem solved.

1 Like
8

Is the general rule of thumb that your throttle should ALWAYS be all the way up?

2 Likes
9

Yes, usually. The machine has a governor that limits it to 3600rpm so it’s not like the engine is gonna blow.

If you need to reduce pressure you do it by changing tip/orifice size. The other guys can elaborate, I’m still fairly new to PW.

1 Like
10

Yes I always keep the throttle all the way up and just choke it for a quick second when starting it.

1 Like
11

Yeah sounds like your idle being low is the problem. You should be getting closer to 5gpm at full throttle. There’s no reason to have it below full throttle. Your ratio of 8:1 may climb a bit to 9 or 10:1 but that’s still good.

1 Like