10 gpm pump question.....

I've been doing residential pressure washing for about 13 years.
I have an 18hp Honda motor and a 6gpm General Pump with a gear box.
I had a mechanic failure over the weekend on the 6gpm pump.. I have a Udor 10gpm pump sitting around doing nothing.
I have alot of work lined up and have a back up machine ,granted it's a smaller 13hp. But my question is...

Can I hook up this Udor 10gpm pump , (has a gear box) to my 18h.p. Honda . Same design and everything as my GP . Just slip on the shaft
and go. Question is... I don't own a tank and run off of residential water . I understand the theory of it drawing too much water.
Is there a way I can run this machine and pump temporarily until I get my other pump fixed ?

Like dumb down the idle and play around with the unloader a bit.
There's got to be a way to minimize the water flow through the pump . ? right ?

I don't think it's going to work. Even if you turn down the throttle, The pump still needs the minimum gpm. I tried the same thing many years ago and the pump still cavitated so I had to stop before ruining the pump.

Unless I'm mistaken and if so, Someone will correct me, The only thing turning down the throttle will do is affect the psi.

I don't think the 18 hp will have the grunt to run the pump. If it does, its going to put a hell of a strain on it. And take into account the fact that the engine is air cooled. They need to run at pretty much max rpm to create the needed airflow.

I'm gonna see what happens.I'll report back here during the week.

Adjusting unloaders is more complicated than lowering the rpm. Just don't use the same nozzles you did with your smaller pump. You might run size 15 nozzles if you have them. Also, definitely plumb both inlets with at least 1 diameter hose so you don't starve the pump.

Just hook it up and she will run although not too full capacity. I have a 10 gpm pump attached to a 35 hp diesel engine. I run the engine at different rpm's depending on the job and just switch out the nozzles to change the pressure and the volume. My engine is liquid cooled so RPM's don't really matter, but I can get high psi at idle with a small nozzle which is a low gpm. You won't achieve 10 gpm, but you should be able to get the 6 gpm with the nozzles you were running before.