3.75 Hp pressure washer motor surging?

[hawkeye08]

as stated already, dump the gas, put fresh in with cleaner in it (like seafoam or lucas) and run it. I just had my riding mower do this (didn't get all the gas out last fall, did not use stabil).

I added some lucas gas treatment to tank, ran it until it was out of gas (had to run lower throttle where it did not surge until it ran out of gas). I added fresh gas (with lucas), ran it awhile and then parked it for a few days. When I started it to finish the lawn (after the snow melted off), it ran smooth.

 

[Jay4200]

Clean that carb..........either by just flushing it out, dismantling it and blowing it out, a carb cleaner, or a new one...........ONCE you are positive that it is right.........

+1 on the carb. "Surging", or RPM oscillation is caused by a lean condition. Running lean slows engine throttle response, which causes additional phase shift in the governor loop. If it gets bad enough, the loop oscillates.

Open up your carb bowl and check the main jet. I'll bet everything is dirty. Scrub out the innards of the carb using aerosol carb cleaner (ala WalMart). Soak it good, let it sit, then soak it more. Blast through all of the holes and passages you can find. I like to remove the jet then soak it in a bath of cleaner (I fill up the carb bowl and drop the jet in). You can also probably get a new jet at a motorcycle shop, but you should be able to clean the one in there.

JayC

 

[Gale Hawkins]

Personally I would mix Sea Foam (I know that works and is what I stock but know there are other options that works) 4 oz to a gallon with fresh gas.

It is going to smoke some but that is OK. The cool think is it actually works to soften varnish when it is not even in use facter it gets sucked into the carb.

The old MH came with a generator that would load up and surge so back that I would have to just shut it off but after a good while it when and still runs fine.

Nothing works right with a dirty carb.:thumbsup:

NOTE: That engine will run on pure Sea Foam based on our small engine use I learned accidently. I was going to "pickle" an generator engine with Sea Foam so when the last drops of gas started to leave the tank I started pouring Sea Foam into the tank.

Of course the engine was running at 3600 RPM and when it started to bog on pure Sea Foam I gave it full choke to suck in as much Sea Foam as possible into the carb/engine.

Lo and behold it picked up and ran fine as long as there was Sea Foam in the gas tank. I have repeated this with other small engines. I guess it is like the old tractors that you could start on gas and when they got hot switch them them to kerosene.

Yes when filled with gas they started fine the next time I started them but did smoke.

 

[XPBRUCE]

Thank you all for your reply's.

Been busy working on other stuff so hope to take real close look at the pump, took cab off and clean it new plug, same.

When I get'er fixed will let all you know what it was.


Thanks again
Bruce

 

[Elcid76]

You have air in the water line. We have real problems with this in power plants, we call it voids. You have to have a steady stream of water out the wand BEFORE you start the engine. The same thing kills water pumps in vehicles. Pumps do not like air pockets. There is nothing wrong with the engine.

 

[XPBRUCE]

I've had this PW for about 4 years. Was working fine and then started the surging last fall. Change the plug, cleaned carb runs the same. Know all about having good water supply. When rpm's up has good power spraying.
The carb is a pulsa prime carb right on the tank no float bowl.
Have not had the time to mess with it again. Maybe later this week.

Again thanks for all the reply's
Bruce

 

[mostly_gas]

The old pulsa jet carbs were notorious for the same behavior. Replacing the diaphragm would often fix them, if the tank warped at all there was a .002 "washer" that would help seal the extra gas out of the carb. Your symptoms sound very similar. <y suggestion is go to a good B & S part house and see what gasket kits they have for that carb.

 

[XPBRUCE]

Sorry just getting back as said I'd let you all know what was wrong Mosty Gas was right $3'40 gasket set did the trick. Thanks all for the help.

Bruce