Pump runs, no pressure '76 Sovereign

[Hummer]

Hi yawl, 76 Sovereign mid berth has been sitting up under a shed for about 21 months. I was in a wreck in 2013 (got rear ended and knocked cold, messed up shoulder and discs in neck) and have not been in any shape to put it on the road. But we have decided to go to the NRA Meetings in Nashville, Tn next week so I hooked her up and pulled it out a couple days ago.

Before putting her to bed I drained tanks like I have been doing since 2010 when I got her and before, put water in tank and turn on pump and it pressured right up.

Pump runs fine but won't build pressure. I hooked up city water and pressured system up and got all the air out of all lines and no leaks.

Just inside hatch under counter on the left I have always been able to see water flowing through the filter. It has the letters PAR on it and has a clear top and blue bottom. I can see some water movement in the very bottom but not like it used to flow.

I checked air in all tires and pulled it to town and back thinking the sloshing water might loosen something up but to no avail.

There is no leaks around the filter and I am thinking there must be a air leak as the system normally pressures up and quits and has held quite well in our trips in 10,11, 12.

I am thinking of loosening the screw to the cap on the PAR filter assuming this will allow access to the filter screen to see what is happening????

Thought I would querry your guys first.

[J. Morgan]

Two possible issues, the pump is failing (or the check valves are stuck), OR there is a leak between the tank and the pump, so that the pump is sucking air...


1/2 Ton 4WD Truck, 72 Sovereign Hensley Arrow

[Hummer]

Thanks,

I have to pull the stove out to get back to the pump so will do that tomorrow and see if I can tell what is going on. I have had it out before when I got rid of the AS power supply and got a new one that is much lighter.

The rubber hoses are only 39 years old so..................................haha

Hope the pump is not shot.

If it is shot, are there any recommendations for a replacement pump? Or a kit for the AS pump?

[HowieE]

Most likely the pump is not picking up a prime. Disconnect the line on the input side of the pump and connect a short hose there. Put that hose in some water at or above the pump and test it. If the pump picks up a prime and pressurizes the system it will most likely work when put back to the fresh water tank.

[A W Warn]

Depends on the type of pump. If the pump is the original, it could be a diaphragm pump. Those diaphragms get dry rot cracks in the rubber so there's no vacuum created. ODM used to carry a rebuild kit, I overhauled one of these pumps a long time ago.
If it has been replaced it is likely to have an impeller pump. Once you get into it you will have to figure out what you need. Before removing anything, try tightening the pipe fittings at the pump. If the hoses are dry rotted or the fittings are loose and letting air into the suctions side, neither type pump will work.

edit: You can get a descent new pump for less than $100. May be worth it to go prepared.

[Hummer]

OK I just went out and pulled out the stove and first removed the inlet line and put my finger over the inlet and there was just a hint of suction. I don't think it would have snuffed out a small candle flame.

I pulled the outlet off and the check valve is nice and free.

I pulled the filter off, completely free.

I shot air down the line going to the tank, no obstruction.

Now this may or may not be significant. I poured a little water on top of the diaphragm and the at the edges of the diaphragm lots of foaming water developed just like a bead leak on a tire when checked with soapy water foam develops at the seepage point.

I am going to try the priming thing tomorrow or Saturday. Excellent suggestion. I was thinking about priming it but couldn't think how to get the water in as there is almost no room.

Thanks guys.

[idroba]

Originally Posted by Hummer

OK
Now this may or may not be significant. I poured a little water on top of the diaphragm and the at the edges of the diaphragm lots of foaming water developed just like a bead leak on a tire when checked with soapy water foam develops at the seepage point.

You have found the problem most likely. I assume it is a PAR pump with the diaphragm on the top, driven by an eccentric crank.

If the Diaphragm is leaking you will not develop the suction needed.

Parts are available still for PAR pumps but not many RV supply places stock them anymore. They are costly too.

You might consider replacing your pump with a new Shur Flo or Flow Jet pump. Both are good, and both will pump more water at a higher pressure than the PAR of old.

[Hummer]

It definitely appears to be original.

I was in hopes if I could get it primed it might do enough to get me going for this one trip as we leave in about five days.

I don't have much experience with pumps but do know the electric fuel pump (3-5 lbs pressure) I put on one of my old Onan generators had one heck of a lot more suction than this one.

I will try to prime it initially. Then again if it does prime I will probably be seeing water coming by the diaphragm where I am now seeing air bubbles........, can't hurt to see.

As that now famous saying goes "At this point what difference does it make?" haha

[Hummer]

Just went out and disconnected inlet line, attached a short piece of hose long enough to reach top of counter. I prefilled the hose and stuck it in gal jug of water and engaged the pump, came up right quick and emptied gal jug in a few seconds. Noticed a little foam and water around the diaphragm.

I put more water in the pump and rehooked the onboard supply line up and engaged the pump, did a great job for about ten seconds putting water in the sink and then the pressure subsided and backed off to a drizzle.

It has even more water on top of the diaphragm (I checked and previous water/foam from last night had dried) and the foaming white bubbles were back like last night so I guess this is proof positive the diaphragm is has Gone South.

We will still hit the road and carry about five gallons of extra water in jugs to operate the head while on the road and I will address this when I get back. I just hope I can get a wrench in there to remove the four bolts holding the top of the pump together without having to disconnect the and remove the whole thing as that will be somewhat major.

When I got it I found the power supply laying on top of the pump as the power supply shelf had broken off and the shelf and power supply dropped. I replaced the power supply with a solid state unit about 30 pounds lighter and have it mounted on a bulkhead to the right of the sink. I made up a partition wall that now holds the fuze panel.

Has anyone got a exploded view of the inside of this pump?

[mimiandrews]

I replaced the old PAR pump in our trailer last fall. It failed halfway through winterizing.

I had to re-build a few PEX water lines to fit the hookups on the new Surflo pump, but it was nothing major. If the new pump ever fails, the connections make it very easy to replace and they're available almost anywhere in the country. Cost is less than the parts to rebuild the old pump.

I'd vote for replacing your pump with something more modern.

[featherbedder]

Originally Posted by Hummer

Just went out and disconnected inlet line, attached a short piece of hose long enough to reach top of counter. I prefilled the hose and stuck it in gal jug of water and engaged the pump, came up right quick and emptied gal jug in a few seconds. Noticed a little foam and water around the diaphragm.

I put more water in the pump and rehooked the onboard supply line up and engaged the pump, did a great job for about ten seconds putting water in the sink and then the pressure subsided and backed off to a drizzle.

It has even more water on top of the diaphragm (I checked and previous water/foam from last night had dried) and the foaming white bubbles were back like last night so I guess this is proof positive the diaphragm is has Gone South.

We will still hit the road and carry about five gallons of extra water in jugs to operate the head while on the road and I will address this when I get back. I just hope I can get a wrench in there to remove the four bolts holding the top of the pump together without having to disconnect the and remove the whole thing as that will be somewhat major.

When I got it I found the power supply laying on top of the pump as the power supply shelf had broken off and the shelf and power supply dropped. I replaced the power supply with a solid state unit about 30 pounds lighter and have it mounted on a bulkhead to the right of the sink. I made up a partition wall that now holds the fuze panel.

Has anyone got a exploded view of the inside of this pump?

The old univolt very heavy often broke shelf. I replaced w/3 stage conv. put piece of 1x1 at both corners at front, no more sagging shelf, as to Pump I would replace as others have posted & you can buy on ebay or else where & have in time for trip.