Pressure washer engine rpm's drop when in use

Clean County PW

Clean County PW

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Now that I changed my oil/spark plug/air filter/gas filter/oil filter/pump oil my PW starts with no problem again.

Of course now I have a new problem. When the PW engine is running it sounds smooth. When I squeeze the trigger on the wand the engine sounds like its rpm's have dropped alot and the water pressure drops down at least 1000psi.

What on earth could be causing this to happen????
 
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Just had this exact problem. I have a Delco RK-43. It has the General TS 2021. You know when you take the caps off the pump you have the valve what ever you call them, in there? The plastic thing with the springs. You should be able to blow through them but NOT be able to suck through them. I took all 6 caps off and went through them one by one doing this. I found one valve that wasn't sealing. I could suck air through it. I rinsed it off then I put water in my mouth and blew the water through the valve. Then I tried to suck air through it and it resealed. I put it back in and everything worked fine. Tell me if this is what is happening to you. You start the machine and everything seems fine. The engine runs fine when the pump is in bypass. When you pull the trigger you get the initial high psi spray but then it drops after about 1 second. You get about half the psi you should. If you try and manually rev the engine it just wants to die on you. Does that sound about right? Like I said there is probably a piece of snad in there not letting the valve seal properly. I know that it seems hard to believe that a tiny piece of sand or something could cause that big of a problem. All I know is I did what I told you and everything is running fine. I have ran it for 12 hours since that has happened and she runs smooth. Make sure when you put the valves back in that you get them seated properly. In my General they pop back in place. In case it is a General pump, it takes a 23mm socket to get them off. It did on mine anyway. Hope this helps.
 
I'm thinking you've lost a cylinder somehow. Either a valve isn't closing properly, an ignition coil has failed, or, as I have seen many times on the Vanguard, the wire that grounds the coils when you turn the key switch off has gone bad. This wire runs between the coils and ends at the ground terminal on the right side of the fan cover just above the starter where the black wire from the key switch hooks up. There are diodes in the wire and if one or both fail, one coil will ground out the other. Get a spark tester and check for spark on both plug wires. If one is firing and one is not, this would be my first suspect. If you are at all familiar with engine repair, you can check the wire by removing the fan cover, disconnecting the ground wire from the ignition coils and check for continuity through the wire with a meter. It should show continuity in one direction only. If you show continuity whichever way you hook the test leads to it, the diode is bad. Call a Briggs dealer with your model, type, and code numbers for the correct part. When you reinstall the wire, be sure it won't touch the flywheel.
 
I too thought it was a engine problem and had it looked over by a Briggs dealer. They said nothing wrong. The engine he said runs smooth when the pump is in bypass(no load). Then he pulls the trigger and the rpms drop and he gets half the psi. I am just about positive it is what I stated above. Everything he described is what happened to me last thursday. If he lost a cylinder would it still run smooth under no load?
 
Did you mess with the unloader? If the unloader is set too high the engine will bogg down and the pressure will drop from the load.

Try adjusting the unloader down counter clockwize.
A plugged spray tip or a plugged coil will also cause this problem.
 
Ok, I know this is an OLD thread, but I'd like to know how this turned out. I started digging recently. My Delco Cobalt started doing this SAME thing. Runs like a dream in bypass, decently when using low pressure on a house, and terrible when trying to wash concrete. Its a ts1021 5gpm @3500 psi. Running a 5.5 tip, I'm only getting 1900 at the gun and the engine sounds like its straining and starts to "lope". The rpms will jump around like its running cold. When I stop flowing, it goes up to and holds 3500 nicely. I tried changing the oil the other day to see if that would help and it did nothing.
 
dsnorrod said:
Ok, I know this is an OLD thread, but I'd like to know how this turned out. I started digging recently. My Delco Cobalt started doing this SAME thing. Runs like a dream in bypass, decently when using low pressure on a house, and terrible when trying to wash concrete. Its a ts1021 5gpm @3500 psi. Running a 5.5 tip, I'm only getting 1900 at the gun and the engine sounds like its straining and starts to "lope". The rpms will jump around like its running cold. When I stop flowing, it goes up to and holds 3500 nicely. I tried changing the oil the other day to see if that would help and it did nothing.
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Bump--Can someone help Daniel here?? I had this problem years ago and my local distributor fixed it so I can't remember for the life of me what caused this problem and what my Distributor did to fix this problem.
 
Daniel, sorry I missed this one. Has it been like this since you started using it this year, or has it run okay until recently? If it was stored for the winter without fuel stabilizer, gas may have varnished up in the carburetor. Try pulling the choke closed a little and see if it runs better.

If not, you've probably got a cylinder down. Double check that you've got spark at both plugs. Could be a coil gone bad, a bad plug, or the wire that connects both coils to ground may have failed. The wire has 2 diodes in it and if one burns out, one coil grounds out the other.
 
Thanks guys. It has been going on all season so far. It was stored with Seafoam in the fuel and when I de-winterized it, it got oil change, new fuel filter, and a new air filter. Russ, remember last season, it had that problem not tripping the pressure switch to turn my burner off? It is still doing that also. That's why I was confused whether it was the engine or unloader, but if it's the unloader, it wouldn't hit 3500 and hold it at bypass would it?

I'm at work at the fire department tomorrow but I'll check for spark on Saturday morning. I have a Starbucks to do Tuesday night so I'm getting really stressed about not hitting the right pressure. Their concrete isn't bad at all since its a pretty new store, but it can EASILY turn into many more restauraunts in our town.
 
Daniel, is your gauge in line or on the pump head? If it's on the head, it should zero out on bypass. If it's in line you'll see the trapped pressure in the hose. We've GOT to get the problem fixed so the pressure switch will shut the flame off when you're not spraying...the results could be catastrophic.
 
Russ, I have a gauge on the pump head as well as an inline one at the gun. In bypass, the pump gauge does zero out, and the inline one at the gun holds 3500. I agree with you about the danger of it. I haven't been using heat unless I have someone with me that stays at the trailer so I can signal to them to switch off the burner.
 
You sent me a new one last summer. When I have the switch in my hand (old one plugging the port on the unloader) I can manually switch it. So the switch works, but when it is installed on the unloader, it doesn't.

Oh...and I do have a new unloader that is not installed. I purchased it while placing another order from Pressure Tek thinking that it was the problem, and wanted to get it on the way. I may try installing it tomorrow as well.
 
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