Pump Nightmare HELP!!



Hello All.

I have a Hotsy unit with a Hawke pump. Its a 1270SS model with 4000PSI and 4.5GPM. It sucks from a 325 gallon tank. The tank is in the middle of the trailer with 8 feet of hose going to the pump. I used to have a inverted U shape valve assy. to divert the suction from the float tank to the large tank and vice versa. I experienced pulsation and low pressure with this setup. Took it to Hotsy sales rep and he replaced seals and said lose the valve assy. I now route right from the big tank through a brand new screen filter to the pump. There is still 8 feet of 3/4 hose feeding the pump and the rise from the floor of the trailer is about 2 feet. I can attain only 3200psi with the gun running. The gauge is 20 feet from the pump right before the hose reel. I still have pulsation as well. I have been told that turning the machine around which will shorten the supply hose by 3 feet will fix it. I don't see how. The unit has only about 35 hours on it with the seal overhaul at 8 hours. I think my pump has issues but don't know what. I bought a new seal kit and am going to learn to inspect the pump seals and ceramics to do my own maintenance. I am very mechanically friendly and doing so doesn't worry me. I pulled the brass caps off the pump and don't see any seals. Do I have to pull the entire pump head? If so, will oil come out? I haven't messed with the unloader and the suction line for soap is always closed tight.

This unit is frustrating me beyond words. Any help would be greatly appreciated.

Chuck Richard

New Member
I don't know what your problem is but i know its not the length of the hose. Last time i had pulsation it was a cracked ceramic. ALSO make sure its not sucking air from anywhere.


New Member
You may have air getting in somewere, tighten all clamps!

dose it still pulsate when the tank is full? if so the leight of the hose is not the problem.

what kind of a pump is a 1270ss, take your caps back off , pull the cups out and see if you can suck air through the big end of the cup, if you can then replace the cups.



Moderator / Sponsor
I would try force feeding the pump to start with.

Look for leaks around the pump while force feeding it.
Did the pressure drop before or after the pulsation started?

OK you asked for instruction on repairing the pump, more specifically replace seals.
I assume you are referring to water seals / packing.

Here we go:

Remove head bolts, remove head from pump. (do not pry between head and pump body as you could damage pump & head) Sometimes the head will slide right off other times you will need to to rock the head sideways as you pull it off.

When you get the head off check for cracked or broken plungers. Assuming that your plungers are all OK proceed with inspecting packing next.

If the packing is damaged and it appears that sections of the seal were blown away, this would indicate cavitation of the pump, caused by inadequate water supply and or air leaks in the suction.

If the packing seem glazed or melted that would indicate overheating of the seals usually caused by running the pump in an extended bypass.

When replacing the seals especially if you do not have a manual do one cylinder at a time only!

I suggest you get a breakdown from your local guy or from Hotsy it will be very helpful when reassembling your pump.

Below is a breakdown of a General TS2021 pump your pump is probably similar, but you need to get the breakdown, and headbolt torque specs for your pump.

View the page in this link for more troubleshooting info:

General Pump Troubleshooting

Troubleshooting Ar pumps

Here is a breakdown of the General TS2021 pump, your pump has some similarities to it.
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The pump is a Hawke, don't know the exact model.


Thanks for the exploded diagram, it looks exactly like that. I am going to pull all the checkvalves to see that they are clear then check the seals. I haven't force fed the pump but I had assumed that would've been done at the dealer. Maybe not. The tank level doesn't matter as far as the pulsation goes. I will go force feed the beast today or tomorrow and see. That sounds like it would be the best test.

I'll let you know, thanks for the assistance thus far guys.


Bill B

New Member
Agree with Mark - force feed the pump (check the feed to the pump to be sure you have a flow rate of 20% or so greater than the pump spec.
Did you "calibrate" the unloader? There have been posts on this and / or other boards regarding the proper way to do this.


I took the pump head off, checked the seals and ceramics, all look great. I replaced the head and arranged my plumbing to force feed the pump. The force feed didn't reveal any leaks. I checked all the clamps and they are tight. I ran the unit and it is running at 3700 pounds now. I gained 600-800 pounds just by doing that? I still have the pulsation if I run from force feed or from the big tank.

The unloader could be the problem, but I don't know what to look for. The large knob is snug and only moves a fraction of an inch. There is a nylock nut on top that may be restricting movement of the knob. Should I loosen the nylock nut and crank the valve all the way open? Could this possbily create the pulsation?

Thanks in advance.


Moderator / Sponsor
Have you checked for debris in the check valves?

Have you gone to the troubleshootink links I listed above in my earlier post?

Call me if you like. I will be in the shop for another 3 hours today.

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