[Jettaway]

I have a 16 LPM interpump, did a bucket test the other day and it was chucking out about 14.5-15 LPM.  I tried it with the correct size (05) nozzle and also without a nozzle in.

I have a gravity fed 120(ish)L tank to feed the pump with a 3/4 suction hose. Engine is 13HP

The tank will naturally drain out 7LPM so pump is only having to suck the other 7-8LPM.

Any ideas on why the pumps underperforming or if it is just normal.

I am toying with the idea of twin feeding the washer, 14.5LPM isn't a noticeable drop but if pump says 16 then I want 16 out of it.

[chris scott]

How old is the pump?

[Jettaway]

18 month.

[chris scott]

Put some valves in it.

[Jettaway]

Unloader valves?

Might just put a new K5 unloader on it

[chris scott]

These valves  http://www.malcleanse.co.uk/interpump-kit123-6-x-suction-delivery-valves-p-288.html

[Jettaway]

Thanks Chris.

[Kenny83]

Before buying valves check you revs, its probably just under revving, is it a direct drive pump? if so it should be doing 3400rpm, if it has a gearbox on then around 3190rpm... if it had a gearbox on before and you have changed the pump to a direct drive then it will be doing around 200 rpm less which would equate to a drop in flow.
Check that your throttle lever nut (10mm between air filter and exhaust) hasn't come loose, if so, nick it up slightly. also turn the revs to full and then watch for the lever springing back.
If the revs need turning up then you can do this via the posi head screw located just under the air filter, it will have a spring around it, just unwind in half-turn(ish) incriments until the desired rpm is achieved.
unsure of rpm?digital rev counters are about a tenner off ebay

[Jettaway]

Cheers Lee. Will try that first.

[Jettaway]

Checked the throttle lever nut, seems tight enough.

Got rev counter on order. Do I need to check the rpm under load (with pump on) or can I do it free running (no pump on)

[Roland S]

what tacho should i be looking at on ebay? i'm assuming i don't want a laser type i need something that you put against spark plug lead or do i? (for honda gx engines)