I'm looking for a replacement impeller for a 1 1/2 hp centrifugal pump (for irrigation) and the only info I have for the pump a partial plate on the electric motor. This pump probably is about twenty years old.

Pump turning slow because of a bad bearing, stuck starter switch, bad shaft seal, or bad motor winding will cause loss of flow.
ANY leak in the suction including the shaft seal will cause flow loss.
Plugged impeller will cause loss of flow.
Plugged discharge (inside the case) will cause loss of flow.

Good luck

This could be a lot of things. You need to post the model number for better info, but it could be:

1. A capacitor in the motor is bad.
2. There is a floating voltage affecting a GFI.
3. There is a load factor on the armature.

That is a sign that the intake is either not big enough or there is a leak in the suction side.

I called Lowes then Utilitech and they sent me a new impeller. There were no instructions about how far to thread the impeller onto the post. I am going back in to thread it all the way to the top. I wish I had requested a brass impeller.

Try: http://www.buycheapr.com/us/result.jsp?ga=us92&q=utilitech+parts+for+pumps
I am not sure but I found them on the web.

CRACKED LID BAD LID O-RING,SUCTION LEAK, OR CLOGGED IMPELLER, LOOK AT YOUR BASKET IF IT HAS CRACKS, CHANCES ARE THE IMPELLER IS GOT **** IN IT. SPLIT THE PUMP AND CLEAN OUT THE IMPELLER , GET A NEW BASKET ASAP.. REMEMBER TO (PRIME THAT PUMP) AFTER ANY REPAIR !!!!
JAY THE POOL PUMP MOTOR REPAIR GUY IN LONGWOOD FLORIDA

When you open the pump up look to see if you have a set screw in the center of the impeller. This is a left hand screw, start by removing it. Remove the diffuser from the front of the impeller. Quite often you can just take a screwdriver and wedge it into the left side of the impeller and hit it a good shot with a hammer straight down to break the impeller free. Then just screw it off.
If that dosn't work then you have to open the back of the motor and get to the end of the motor shaft. The end will be squared off so you can get a wrench on it. Then take a big pair of water pump pliers and get the front impeller and unscrew it.
The metal in the impeller and the steel shaft will stick to each other so you will have to break it free. At that point the seal plate will come off.
When your done and putting it back together be sure to replace the seal and all the "O" rings.
Good luck.

GOULD ..OH BOY HERE WE GO... YOU MUST HOLD THE SHAFT AT THE BACK OF THE MOTOR WITH A 7/16 TAKE THE CAPACITOR OFF (LOOK AT HOW WIRES ARE ROUTED ) OR 1/2 INCH WRENCH THEN UNSCREW IMPELLER..
>BEST TO BRING IT TO YOUR LOCAL POOL PUMP MOTOR REPAIR GUY OR PUMP REPAIR ,USE YOUR ZIP CODE IN YOUR SEARCH.. DON'T TRY TO REPAIR THIS IF YOU BREAK IT IT WILL COST YOU !

Impeller will be threaded on, remove by turning counterclockwise

replace the pressure guage.
prime the pump by pouring in water in the impeller basket area and replace lid-try running pump again