Here's an unpleasant question...

[jimmy_the_builder]

I've had my targa 40 for about three months now, and in general I love it. However, since I've had the boat, the holding tank overboard discharge hasn't worked properly. To cut a long and unpleasant story short, the pump seems to work intermittently - it spins ok, but sometimes it'll move waste from the tank, and sometimes it won't. I've checked everything I can think of - I've replaced the impeller in the pump (it's a Johnson macerator pump), although the old impeller looked fine; I've checked the non-return valve downstream of the pump, I've checked the pickup pipe for blockages, all seems ok.

So tonight I removed the pump and powered it up briefly. One thing that struck me as odd - if I cover the inlet spigot with my hand, there's no suction. That's not right, is it? I can't see why there is no suction when the pump appears to be turning and the impeller is new. Is this because the pump was dry? Or does it indicate a fault with the pump?

Cheers
Jimmy

 

[gjgm]

surely this type of crappy question should be on PBO ?

 

[wattsn]

Will be watching this one with interest as the waste pump light has started flashing on ours even though it has only had about two wees in the toilet. Have left the pump out ruinning a while and it continues to flash green/red indicating over 80% full. But it can't be, unless it's not emptying.

Keeping a close eye on this thread.

 

[jimmy_the_builder]

surely this type of crappy question should be on PBO ?

There's no need to be so sh**ty...

Cheers
Jimmy

 

[jimmy_the_builder]

Will be watching this one with interest as the waste pump light has started flashing on ours even though it has only had about two wees in the toilet. Have left the pump out ruinning a while and it continues to flash green/red indicating over 80% full. But it can't be, unless it's not emptying.

Keeping a close eye on this thread.

Have a look in the inspection hatch in the tank, if you have one?

Cheers
Jimmy

 

[BartW]

a few years ago had a similar problem,

there was a peanut stuck in the non return valve, so valve was alway's partly open, so pump could not suck

real ****ty work to find out and solve

good luck

 

[Alistairr]

So tonight I removed the pump and powered it up briefly. One thing that struck me as odd..

Thats pretty dangerous,,,,,, A few odd things could've struck you!!!

Al.

 

[jimmy_the_builder]

Thats pretty dangerous,,,,,, A few odd things could've struck you!!!

Al.

Ha! Even less pleasantly, I'd already had it apart and cleaned it, so no danger of that!

Cheers
Jimmy

 

[jfm]

I've had my targa 40 for about three months now, and in general I love it. However, since I've had the boat, the holding tank overboard discharge hasn't worked properly. To cut a long and unpleasant story short, the pump seems to work intermittently - it spins ok, but sometimes it'll move waste from the tank, and sometimes it won't. I've checked everything I can think of - I've replaced the impeller in the pump (it's a Johnson macerator pump), although the old impeller looked fine; I've checked the non-return valve downstream of the pump, I've checked the pickup pipe for blockages, all seems ok.

So tonight I removed the pump and powered it up briefly. One thing that struck me as odd - if I cover the inlet spigot with my hand, there's no suction. That's not right, is it? I can't see why there is no suction when the pump appears to be turning and the impeller is new. Is this because the pump was dry? Or does it indicate a fault with the pump?

Cheers
Jimmy

I'm familiar w the johnson. More than I want to be. Got thru 5 on last boat. No suction says thereks a fault. Its a jabsco impeller style pump intended to be mounted above black tank and self prime. No suction feel means summink aint working. When you bench ran it could it lift water a metre, self priming? If not its bust
The fault may not be impeller tips. It might be failure to seal on the face of the impeller, onto the flate end plate of the pump chamber

Solution is buy whole new pump. If doing that you'd be much better getting a diaphragm pump (I have that on new boat, loads better and can run dry). However most diaphragm pumps want 38mm on the outlet and your piping downstream of pump is likely 25mm in which case get another johnson (about £100 iirc)

Good luck and have a good shower when done!

 

[jimmy_the_builder]

I'm familiar w the johnson. More than I want to be. Got thru 5 on last boat. No suction says thereks a fault. Its a jabsco impeller style pump intended to be mounted above black tank and self prime. No suction feel means summink aint working. When you bench ran it could it lift water a metre, self priming? If not its bust
The fault may not be impeller tips. It might be failure to seal on the face of the impeller, onto the flate end plate of the pump chamber

Solution is buy whole new pump. If doing that you'd be much better getting a diaphragm pump (I have that on new boat, loads better and can run dry). However most diaphragm pumps want 38mm on the outlet and your piping downstream of pump is likely 25mm in which case get another johnson (about £100 iirc)

Good luck and have a good shower when done!

Evening jfm - that's helpful. It's an intermittent fault - so on two runs it will lift, and on the third it lifted to maybe 20cm and then wouldn't lift further. Wear plate looks ok, gasket and o-ring are both new.

I would much rather chuck it and fit a diaphragm pump - but as you suggest, the existing outlet pipework/non return/sea cock is 25mm.

Sounds like a new pump then. I wish I'd tried this suction test before I went through all the hugely unpleasant exercise of checking the pickup connections _in_ the tank...

Cheers
Jimmy

 

[wattsn]

Have a look in the inspection hatch in the tank, if you have one?

Cheers
Jimmy

Nose peg required I guess?

 

[jimmy_the_builder]

Nose peg required I guess?

Oh very yes. And do you want to be certain it is not completely overflowingly full before you open the hatch. (My t40 was delivered with a full holding tank, and a faulty holding tank gauge which suggested it was empty. I only discovered that it was full when we flushed the loo and displaced holding tank contents came out the breather pipe...).

I told you this was an unpleasant question!

Cheers
Jimmy

 

[wattsn]

What's the longest you can / should leave the waste pump running?

I read another thread which suggested if it had not emptied within a few minutes then it was either blocked or broken.

 

[jimmy_the_builder]

What's the longest you can / should leave the waste pump running?

I read another thread which suggested if it had not emptied within a few minutes then it was either blocked or broken.

I don't know how long before they self-destruct ... but the macerator pump on my boat is rated at 10gpm so I guess it should empty a full 200 litre holding tank in 5 minutes.

Cheers
Jimmy

 

[paultallett]

Hi Jimmy,

I had the same problem with mine when we first bought the boat. I got a complete service kit for the pump.....this also included a new backing plate. Once all the parts where replaced, no more problems!! I'm just wondering if the impellor can't get a good seal because of a worn backing plate??

Regards Paul.

 

[jimmy_the_builder]

Hi Jimmy,

I had the same problem with mine when we first bought the boat. I got a complete service kit for the pump.....this also included a new backing plate. Once all the parts where replaced, no more problems!! I'm just wondering if the impellor can't get a good seal because of a worn backing plate??

Regards Paul.

Cheers Paul. I got a service kit as well, although it definitely didn't include the wear plate, just the impeller and gaskets. I've decided to try and source another pump (although I can't seem to find anyone who actually has these on the shelf, which is annoying cos I would like to get this done and finished!).

Cheers
Jimmy

 

[Petrolia]

Agree with others who suggest diaphram pump. Ours has one & no problems.

 

[Wiggo]

Same problem here a few years ago, right down to dumping the contents out of the breather over the side deck of the boat we were rafted to. Fortunately they were fellow forumites and they were in town shopping at the time...

I fitted a new macerator, but followed the installation instructions and fitted it below the level of the top of the tank so once the tank was more than half full the pump wasn't trying to lift anything and the syphon effect would start to work. Three years on and no problems.

 

[SRB]

Will be watching this one with interest as the waste pump light has started flashing on ours even though it has only had about two wees in the toilet. Have left the pump out ruinning a while and it continues to flash green/red indicating over 80% full. But it can't be, unless it's not emptying.

Keeping a close eye on this thread.

Hi wattsn,
The sender units in the tanks quite often get clogged up, and even though the tank is empty it still shows full,if this is the case im afraid you will have to take the sender out and clean it.

 

[Wiggo]

Which isn't actually as bad a s it sounds. It just unbolts and needs rinsing under running water, or a scrape with a toothbrush if it's really clogged.