Water Pump Doesn't Work - When City Water is Disconnected

Sorry I haven't been online in a couple days and didn't receive email notifications of your responses. Thank you for the replies and information, especially the adjustment instructions.

Lakejumper why don't you phone Shurflo and explain your problem with them. They are very proactive. When I had problems with my 3 year old 4008 they sent me out free of charge a whole new head which solved my problem of the pump not pumping water.

Lakejumper wrote:
Old Biscuit, it is a Shurflo 4008-1. I was proactive when this issue started a couple of trips ago and I purchased a new pump. I have replaced one in another RV before so I may try to do this one. The only problem is that this pump is very difficult to reach as it is screwed against the back panel in the utility compartment. I also heard that the pump has an adjustment screw on it and I don't know how to adjust it.

That pump has TWO adjustment screws

One for start/stop pressure setting
One for the internal bypass pressure setting

Internal bypass allows for pump to continue to run when there is low flow demand (older style pumps would start/stop during low flow demands)

Normally you would need to have a pressure gauge on RV cold water line so that you could make adjustments.
Start/Stop pressure switch would be set for 55 PSI
Bypass setting would be for 62 psi

BUT you can do an 'on the fly' setting for each
Instructions with pictures

Old Biscuit, it is a Shurflo 4008-1. I was proactive when this issue started a couple of trips ago and I purchased a new pump. I have replaced one in another RV before so I may try to do this one. The only problem is that this pump is very difficult to reach as it is screwed against the back panel in the utility compartment. I also heard that the pump has an adjustment screw on it and I don't know how to adjust it.

Sorry - should have said faucet vs valve. If it's not a loose wire then it's likely a problem with the water pump - you can take the pump apart and fix but if it were me I would buy a new pump. There not expensive, easy to install - and taking to a dealer isn't worth it.

Lakejumper wrote:
Wnjj, I think that you might be correct. I did check the winterizing bypass valve and its in the correct position and very difficult to move so that isn't the culprit.

Bypass valve would NOT make pump work or not work.....it strictly just bypasses the water heater. Connects cold line to hot line....period



Pump pressure switch is what starts/stops pump

When hooked up to city water and you turn pump on it doesn't run because system pressure is high enough that pump pressure switch is OPEN

When you disconnect city water....unless you open a faucet (or have a leak) the system pressure remains charged enough to keep pump pressure switch OPEN
When you turn on a faucet/flush toilet etc. system pressure drops, pump pressure switch CLOSES and pump runs

If pump doesn't run.....tap pressure switch (on front/head of pump) as it could be sticking.
If pump runs...then you can remove pressure switch/clean/free it up OR REPLACE pressure switch

Typical RV pumps
Pressure switch OPENS at 45# OR 55#
Pressure switch CLOSES at 30# or 40#

Which BRAND/MODEL is your pump??

Wnjj, I think that you might be correct. I did check the winterizing bypass valve and its in the correct position and very difficult to move so that isn't the culprit.

Sounds to me like a sticky pressure switch in the pump. The higher pressure from the city inlet probably causes it to stick a bit further in. The vibration of road travel frees it up.

Kevin, by turning on a water valve, do you mean faucet? I didn't get any water from the faucet. I know that the pump doesn't always turn on but I wasn't getting any water out of the faucet. I'm going to check the bypass valve to make sure that the hoses didn't hit it when I stored them in the compartment.

As maillemakers says turning on the water pump switch when the water lines are pressurized will not trigger the pump. You say the pump works after travel when you take a break - any chance your turning on a water valve during that break?