B&S made in China 208CC pressure washer engine back fires

[naimc]

This small 208 cc engine will back fire once when I turn off the ignition switch. It does it all the time. Other than that is runs fine. For winter storage I completely drain the gas and remove the pump and bring it inside

Original when I purchased it 2 years ago I adjusted the valve lash, . the code on this engine is 13U2-80098013 made in China engine. the B&S web site does not list this engine but I found a service manual for a 13U200 which looks identical.

Both intake and exhaust were at .10 mm and as per page below I set both at .15 MM. This made the engine easier to start but I am wondering if that`s the cause of the back fire and thus I should re-adjust them back to .10 mm ?

 

[Brian123]

Go back to .10mm and see what happens!

 

[ripcord]

The most reliable way to fix this is to install a fuel shutoff valve on the gas line and use it to run the carb out of fuel instead of killing it with the ignition switch.

The problem is that the engine is still drawing too much fuel while it is slowing down after being shut off. This loads the hot exhaust up with fuel to the point that it combusts. This happens on a lot of OPE when the engine is running too fast when it is turned off. Are you throttling down the engine before you turn it off?

I assume there is no shutoff fuel solenoid sticking out of the bottom of the carb?

 

[fantastic]

Do you reduce the throttle for a minute or so before shutting down? Sounds like fuel is still burning after shut down.

 

[mk378]

It looks like there is no speed control but there is a fuel cutoff valve. If the backfiring bothers you, shut it down by cutting the fuel and let it starve out.

 

[naimc]

The most reliable way to fix this is to install a fuel shutoff valve on the gas line and use it to run the carb out of fuel instead of killing it with the ignition switch.

The problem is that the engine is still drawing too much fuel while it is slowing down after being shut off. This loads the hot exhaust up with fuel to the point that it combusts. This happens on a lot of OPE when the engine is running too fast when it is turned off. Are you throttling down the engine before you turn it off?

I assume there is no shutoff fuel solenoid sticking out of the bottom of the carb?

Yes there is a shut-off, but this is pressure washer with direct attached pump with a built in un-loader, that does not re-circulate the water. the the instant the pressure gun is shutdown the pump start over heating. They, ( the internet the owners manual all say that the engine should be stopped when not in use) . This machine like most with a direct attached pressure washer don't have a manual throttle control they are set to run full speed.

It makes sense that is unburnt fuel that's burning in the exhaust. I though that could be the sign off the carb that's to rich ?

I will check the valves again as my initial adjusted was 2 years ago and typical I tend to be primary cause of the problems I encounter.
The back fire is not a big deal but none of my other engines do this so it's just a pride thing. Let's figure out the cause.

 

[Slick3914]

Try 89 octane gas and it won’t backfire. If that doesn’t work, run it ‘till she blows!

 

[repairman54]

Common to happen when an engine is not idled down and fuel passes through into the hot muffler.
My neighbor does it all the time with his mower, jumps off the seat or just shuts it off without idling down for a few seconds and pow.
My equipment will do the same. As said fuel shut off on that particular engine is the cheap and easy way. Plus your running the carb dry.
Enough backfires will hose the muffler after a while.

 

[Cujet]

The muffler could have a catalyst in it. This remains glowing hot, and when raw fuel enters, it ignites. Normal.