Jabsco Washdown Pump Fault

 Have a Jabsco Par Max 4.0 60 PSI Auto Washdown Pump fitted to boat.

It has worked perfectly for 4 years until after sitting unused for 6 months, has now lost a lot of pressure. Have pulled pump apart , checked top mounted filter, checked all hose fittings and all seems good.

The pump normally operates only when the spray nozzle trigger is activated, however the motor now works constantly when switched on. The problem is the same on both fresh and saltwater washing settings ( only ever use the fresh water setting).

Seems as though it will not prime.

Any help appreciated thanks.


jng's picture

Posts: 488

Date Joined: 03/08/07

Have you checked the pressure

Sat, 2019-11-30 16:36

Have you checked the pressure switch? First thing to fail on those pumps

Go to jay car aprox 4bucks  

emem's picture

Posts: 14

Date Joined: 25/10/15

 Thanks jng. Will check it

Sat, 2019-11-30 18:05

 Thanks jng. Will check it out.

pelagicyachts's picture

Posts: 969

Date Joined: 23/02/11

have same issue with a

Tue, 2019-12-03 10:53

have same issue with a shurflo freshwater pump - stripped down and put back together but just runs constantly and pressure is well down - i pulled the pressure switch apart and was surprised by the strength of the spring inside - but the switch itself was clean - assume that = pump is rs yeah?
putting a weaker spring in will just equal less pressure at the tap....

The Saint's picture

Posts: 359

Date Joined: 30/01/13

Check that it is not

Tue, 2019-12-03 12:26

Check that it is not something as simple as sucking air.

Had a problem with one on a previous boat, a connection on the suction line had a split o-ring.

Struggled to prime and build up pressure so would run constantly.

pelagicyachts's picture

Posts: 969

Date Joined: 23/02/11

nice one didnt think of that

Wed, 2019-12-04 09:26

nice one didnt think of that was focussed on blockages post the pump