More Pressure Washer problems

rszanti(usda 6)October 23, 2005

I have a Craftsman 2600 psi washer (model 580.742780). I can start it easily, it runs 5 to 10 minutes and then quits. I start it back up and it runs 6 to 8 seconds and quits. I can do multiple restarts and get the same run for for 6 to 8 seconds with a following instant shut down - It appears as if the ignition is turned off when it happens. If I let it set for a while I'll get a 3 or 4 minute run before it quits.

I do get a small continuous flow of fuel from the carb bowl whenever I pull the plug from the bottom. The engine oil is at the proper level. This unit only has 3 to 4 hours run time on it.

The unloader assembly seems to be working properly as it opens when I release the nozzle trigger (the engine "unloads") although sometimes I get a pressure lock and must release water pressure via the trigger before I can pull start the engine.

I do know there's a low oil pressure switch on the engine and thought it might be the culprit (warm engine and the lower oil viscosity produces a lower oil pressure) - I tried shorting out the switch but it didn't seem to do anything (maybe that's not the right way to check it ?)

So I'm now at a loss as to what to try next. Any suugestions ?

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canguy(British Columbia)

What engine is on it? Sounds like the ignition module is getting hot and crapping out. Improper valve adjustment (too tight) can cause it too.

    Bookmark   October 24, 2005 at 8:41AM
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rszanti(usda 6)

Canguy -
Other than the Craftsman nameplate, there is no other identifying data (except - ENG 97954 91626). It could be an overheated ignition module but would it still be possibly to start it immediately, while still hot, if it was the module ?

It is an overhead valve engine with a prominent valve cover marked OHV.

    Bookmark   October 24, 2005 at 12:04PM
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jammer1(mass)

I would say a blocked vent in the fuel tank;try loosening the gas cap,(with only a little gas in the tank),a lot until its almost ready to fall off,and see what that does.It sounds to me as though you have a fuel delivery problem,and to find it might be a little tricky,but start at the tank,and work your way to the carb.................You might have some water in the fuel tank............

    Bookmark   October 25, 2005 at 10:02PM
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seth5613

I have the same problem with my pressure washer- also a craftsman. Did you ever find the problem? I took the pump apart and everything- it all looks good. Please let me know. Thanks.

    Bookmark   September 13, 2007 at 8:30PM
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rszanti(usda 6)

Seth

Never did. Tried loosening my fuel cap. Checked for fuel flow at the carb (plenty). Emptied my fuel and reloaded with fresh - still same problem.

Haven't had a chance to play with it since then, it sits in the back of my garage as a reminder of projects needing to be done :-)

I do suspect an ignition module as Canguy suggested and maybe it's that pressure switch I've never gotten any more info on. So I would still like some further suggestions myself.

If you come up with anything please publish it.
Richard

    Bookmark   September 13, 2007 at 8:56PM
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nycjsw(22030)

Not that I am all knowing when it comes to engines but I do believe there could be lots of things causing this problem. Vacuum/air leaks around the carb may be the cause. If you read other threads this is a common problem. The unit will run fine until warmed up and then crap out. Upon restarting it will run for

    Bookmark   September 14, 2007 at 4:39PM
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rszanti(usda 6)

Never thought of that, sounds like something definitely worth checking.

    Bookmark   September 14, 2007 at 5:44PM
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playitsafe

My problem is solved! It was the gas cap. Had the same exact problem as reported by rszanti in October 2005 (the OP). I won't describe my problem because rszanti's first paragraph at the top of this post describes it verbatim.

I will say that I felt my problem was a fuel problem because of how easy it would start after each stall. If the problem was heat related, I would expect more time would be required to let things cool down before it would start again.

>Craftsman 3100 PSI Pressure Washer Model 580.752080 purchase new in 2007
>Briggs & Stratton 121012-0123-B1 900 Series Single Cylinder OHV 4 cycle (no fuel pump or filter)
>No more than 20 hours of use on it.

This is how I diagnosed the problem:

The gas tank has a shut off valve. Closed that and disconnected the fuel hose from the carb. Removed the gas tank from the pressure washer. Held the tank over a gas container and opened the shut off valve. Gas started draining and then got slower and slower until it stopped draining, even though the tank was still full. Loosened the cap and the gas started flowing again.

After draining the tank, I tightened the gas cap and put compressed air at the fuel hose. No air leak.

So my guess as to what was happening is:

The carb bowl has gas and no vacuum exists in the tank. On first start, engine runs for about 5 minutes under full load and then stalls. The stall is caused because vacuum has built up in the tank and there is not enough fuel flow to serve the engine's need under load. The carb bowl empties and the engine stalls. Now the engine sits for a minute. Gas trickles into the carb bowl. On second start, the engine fires up but sucks the carb bowl dry again. (By the way, it will run for a long time if not under load. Probably because it doesn't require as much fuel flow.)

I inspected the cap design closely and it has no vent hole. I'm not sure why the cap worked and now it doesn't. Guessing there was something there that prevented the cap from screwing down too far, and over time it wore down. I didn't see anything on the tank either that would suggest a design for venting.

Anyway, now I screw on the cap so it is almost loose and the pressure washer has worked all afternoon under full load with no stalls. Go figure.

    Bookmark   July 3, 2009 at 3:15PM
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