Shurflo water pump pulsing

[dave renton]

Hi, I have been having some problems with the water system in my T6 campervan. We did most of the conversion ourselves in 2020 but hardly used it due to lockdown, when we did use it a week ago the pump didn't work. We bought a new one, tested it, then fitted it but although the water ran freely on the test i.e. without a tap, when it was connected to the van system it kept pulsing. We are not sure whether the problem is related to the change in diameter between the supply pipe and the tap tail. It is a very simple system: CAK underfloor tank, Shurflo Trail King 7 and a Smev cold tap. When we connected the pump to the tank the water came out of the feed without pulsing so the problem seems to be on the tap side of the pump.
Do you think that we need an accumulator to solve our problem or should we be looking elsewhere?
We had a T4 for 20 years with a very similar system and never had any problems.
Any advice would be most welcome, thanks for your thoughts.

 

[DXX]

Yes you probably need an accumulator
See this case

https://www.t6forum.com/threads/fiamma-aqua-8-issue-or-installation-issue.26443/post-368366

 

[DXX]

@dave renton IMO I think it is a much better solution to fit a submersible pump such as a Whale and a tap with a 12v microswitch.
No accumulator required (more space) and less chance of leaks as the system is not pressurised on stand-by and not much pressure when in use as flowing.

 

[dave renton]

The tank is external. so without cutting an access hole a submersible pump would be difficult. The more general point is well made I've looked at non-diaphragm pumps but I think I'll end up fitting the accumulator hope it fixes the problem. The problem seems to be the change of I/D between the tap tails and the supply pipe. Thanks for all the help

 

[HotandCold]

If you fit an accumulator it will stop the pulsing and also the pump won’t have to run every time you open the tap. My system is similar to yours and works really well.

 

[dave renton]

Just to finish up I have just stripped down the nonworking original pump it wouldn't prime. I found a load of swarf in the valves, the lesson has to be flush your tank and fit an inline filter. Accumulator tomorrow after flushing the tank. At least I now understand how they work and I have a spare pump!!