Hard pumping head

[Jeff Kaplan]

Last year, towards the end of our short season, I found it was hard to pump the head, manual Jabsco.  The head needed replacing so I bought a new manual Jabsco.  Just launched the boat and when I started to prime and pump the new head, found same problem.  Water is drawn in very easy but when handle pushed down, feel pressure resistance.  I can only think that the diverter valve, into holding tank or out to sea, is somehow defective. I don't think it could be the vented loop as water just goes thru it.  The thru hull is clear.  If anyone can shed some light on this matter, I would greatly appreciate it.  I need to get this fixed shortly, as the Tall Ships are parading intro Boston Harbor on Saturday and I have a crew to go and view.

[Noah]

Troubleshoot it in stages, a piece at a time, to isolate problem. 1. Disconnect the discharge hose from the diverter valve, stick it in a bucket or on towels, pump head, and see if it discharges from the hose. Then move down the line.

[Stu Jackson]

Also check the vent from the tank.

There are a number of head issues discussed in the 101 Topics that are worth a look.

[Noah]

If your holding tank is full or close to it, a clogged vent will definately cause hard pumping. Your tank may swell as well.

[Jeff Kaplan]

holding tank is empty, vents clear.  I'm still thinking that it's the diverter valve, rubber shifted to close off some of the waterway, I'll be back on boat tomorrow to  test the advice given.

[Ed Shankle]

Jeff,
Sorry I don't have a definitive answer for you, but want to say that I had that same issue with my Jabsco and I don't have a diverter, always goes into the holding tank. I never solved it, just replaced it with a PHII, which I like much better. With the Jabsco I found that if I held some down pressure on the pump handle, after a few seconds it would eventually release the resistance and I'd be able to pump ok. Might work for you in a pinch until you get to the root cause.

regards,
Ed

[Bobg]

I had a similar problem and it wound up being the valves on top of the handle area, those little brass round things, one side would open and the other would not when put in dry bowl.  I bought the entire plunger system, helped for awhile, now when I flush, air and "liquid" sometimes shoots back out of the bowl "ugh", or when I operate the plunger and hold it down, I get a big "sigh" sound.  I have done just about everything I can think of, (new joker valves, plunger, valves, checked all hoses, vent was momentarily taken off the tank to check that. soaked everything in vinegar, ect), I am in lake superior and the water is crystal clear, I think it is just that the jabsco is a really inferior toilet.

[Stu Jackson]

There is great merit in assigning the issue to the Jabsco mechanism.  Peggie has written repeatedly about this on other boating forums.  Why not here?  'Cuz we've repeatedly mentioned the advantages of the Raritan PHII assemblies and haven't had to repeat much about the Jabscos.

[Noah]

Jabscos are inexpensive and a bit flimsy, with lots of plastic parts that are easy to overtighten, causing leaks. However, I have never had any issues with them not pumping/clearing the bowl.

[mark_53]

Did someone put something they haven't first eaten into the head? 
Can you pump out with the through hull open and does is suck raw water?

[Ron Hill]

All : I always wondered what the Chinese did to the type rubber used in the pump "O" ring they now supply.

25 years ago the pump slid up/down with ease.  Now it might need "head lube"!!

My solution is to take that "O" ring and soak it in silicone to make I more resilient.  It helps.

A few thoughts

[Jeff Kaplan]

I thank all for your replays. The situation has been resolved.  It turns out that years ago I installed an inline strainer in between seacock and head.. I took out the screen the year after, so just water would run thru.  Thru the years, the outlet munged up and caused pressure blockage as I was drawing in water.  The fix, I ran a new line from the seacock to head, and amazingly, no more problems. Going to see the Tall Ships tomorrow, weather is iffy. Thanks again

[KWKloeber]

I thank all for your replays. The situation has been resolved.  It turns out that years ago I installed an inline strainer in between seacock and head.. I took out the screen the year after, so just water would run thru.  Thru the years, the outlet munged up and caused pressure blockage as I was drawing in water.  The fix, I ran a new line from the seacock to head, and amazingly, no more problems. Going to see the Tall Ships tomorrow, weather is iffy. Thanks again

Jeff so the hard pump was on the intake stroke?  not the pump stroke?

ken

[Jeff Kaplan]

it was the pump stroke that was hard, all fixed now, I never should have installed an in line strainer.

[KWKloeber]

it was the pump stroke that was hard, all fixed now, I never should have installed an in line strainer.

Strange, I don't see how a blockage on the inlet side would cause hard pumping on the pump stroke.  Seems it would cause a vacuum when pumping on the intake stroke.

k