B&S 550e No start/gas spitting from carb

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  #1  
Old 01-09-16, 02:02 PM
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B&S 550e No start/gas spitting from carb

Yard sale score of a craftsman 580.750400 model pressure washer. 140cc Ohv 2200psi 1.9 gpm

Has a B&S 09P702-0124-F1 engine.

Brought it home and drained old fuel, filled with new 87 and a little chemtool, no start, no fire.

I cleaned the carb, needle/seat appear to be fine. Float is floating, Needle shuts off if carb is 180 over. Cleaned and flushed the tank as well, filter inside tank was blown clean with shop air. Fuel was old, but not too bad. Replaced fuel reguardless.Carb had minimal amount of gunk in bowl.

Appears to be healthy spark with plug grounded to chassis.

Slight rust on flywheel, got most off with vinager and Greenpad.

Valves move when turned over, have not adjusted them, pushrods appear intact and straight.

On/off switch tested with continuity tester.



When I pull the cord, it will either turn over and not fire, I can hear the compression and smell fuel, or sporadically give one chug of Firing at the end, or spit gas out the carb into the air cleaner.

Spraying starting fluid does nothing,also I can smell gas after several attempts so I'm sure there's flow.


I'm leaning towards a timing issue. But small
Engines aren't my specialty.

Any help you guys/girls, can give would be greatly appreciated. I'm hoping it's something silly, before I really tear into this thing.


It has almost zero hours on it. No dirt/grease/abuse just appears to have been sitting for a while. Or broke, and sat waiting to get fixed..... Guy I got it from said it was from an estate sale, and supposedly ran when purchased.
 
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  #2  
Old 01-09-16, 02:12 PM
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A lot of times that type of no start has to do with old fuel residue in the combustion chamber. Try shutting off all the gas to the carb - empty the bowl if you can. Then take out the plug and with full throttle, no choke spin the engine over five or ten times to purge the old fumes. Then put a spoon full of gas directly in the plug hole, stick the plug back in and pull until it fires. It'll take a few times and may run for a couple of seconds.

Then turn the gas back on the carb and with full choke, half throttle, see if it will start for you.
 
  #3  
Old 01-09-16, 03:00 PM
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Emptied tank, drained carb bowl. Cleared the cylinder with the plug out, added about 1.5ml of fuel. Plug back in, motor turned over slightly, but almost the same as the previous fires. Replaced fuel line, filled tank with brand new fuel. Still nothing.
 
  #4  
Old 01-09-16, 03:03 PM
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Forgot to mention, this model had ZERO controls. No choke, no throttle. The linkage attaches to behind the motor. Some sort of auto choke I imagine. It's just a shaft sticking up out of the block.
 
  #5  
Old 01-09-16, 03:43 PM
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In brief, and not likely on a pressure washer, but maybe a sheared flywheel key if timing is considered.
Try a new spark plug and or an inline tester. Remove the muffler..???
Might also suspect the coil which can be tested to some extent with a multimeter.
Unable to look up the engine atm, but can later.
 
  #6  
Old 01-09-16, 04:29 PM
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If it's trying to fire and you had enough gas in the cylinder to feed back into the carb throat, it may be flooded. In a cold start an auto choke would likely be fully on and the trick is to clear out the combustion chamber and carb throat. It helps if everything is opened up to clear out the head.
Then with the fuel supply cut off completely, add a little directly into the head. Once you get it to fire a couple times the old residue clears out and you're in business. 1.5ml would only be about 1/3 of a teaspoon. I think I'd try at least a full teaspoon.

A new plug may take care of it too. A plug can be fouled where it won't fire in the combustion chamber, but it'll still show a spark outside the engine.
 
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Old 01-09-16, 06:52 PM
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Sounds flooded to me. Try a new plug first. See if the autochoke is holding closed. If so, try with it held open.
 
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Old 01-10-16, 11:27 AM
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ok, so I drained the fuel bowl again, took out the plug and cleared the cylinder, left it open while I went out and got a new plug. Added 4.5ml gas this time with the fuel line disconnected and new plug installed.No luck. In fact this time it also spit gas out of the carb again. When I say spit, I mean it shoots about a foot out of the carb with the air filter removed. Not everytime, but about as often as the "backfire" sound. I tried pulling about 15-20 times, opened the cylinder, cleared it, added more fuel and tried a second time. After I was sure the fuel had been cleared out I tried ether down the carb, no effect either.

Maybe I should clarify "trying to start". When I pull the cord, I hear the compression. A non-running motor has that sound of air just passing through. Compression but no combustion. Every so often I hear a thup at the end of the cycle. Like a backfire, but the motor wasn't running and then shut off. Just a solitary pop. A little combustion pop.


While I had the plug off the last time, I covered the hole with my finger while I turned it over. It had great intake pressure but barely any noticeable on the compression stroke. On my V8 it's noticeable, not sure if a gauge is needed with these small ones or if the finger test is accurate. Stuck/loose valve maybe?


I'm not sure how to bypass auto choke, but I held the linkage open while I tried starting it, it sprayed even more fuel out. no change besides that.

If I'm possitive it's not flooded, and I have spark, have fuel, and have air. The only thing is timing, no? Or could my coil be too weak? Carb needing full rebuild?


When I pull the plug it's clean, no carbon, but most certainly has fuel on it. Sometimes when attempting to start it the exhaust smells of raw fuel, other times burnt fuel.


I appreciate all the help so far!
 
  #9  
Old 01-10-16, 12:38 PM
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Sounds like a sheared flywheel key to me. Have a good one. Geo
 
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Old 01-10-16, 01:15 PM
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The first thing I would check would be the intake valve. Apparently it isn't sealing (eg. gas spitting out carb -- good suction/low compression) for what ever reason. Head removal and inspection is in order.

Happy hunting!

RR
 
  #11  
Old 01-10-16, 03:52 PM
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You're getting a strong suction with the intake stroke and nothing pushing out the plug hole on compression? It would help to see the valves working. With the gas blowing back and no compression it would say intake valve.

From an unknown history there's always a chance it wasn't running at the time of the sale. There isn't a good reason it would go from running well to a messed up intake valve in the sequence you have. It would be more likely to have a flooded engine, but that's not a no compression engine.
 
  #12  
Old 01-11-16, 12:37 PM
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Checked the flywheel key, both keyways are aligned.

Pulled off the head. Both valves are seated properly, the springs and retainers are good. Pushrods are straight. Piston/sleeve looks immaculate. Only buildup was what appears to be gasket sealer around the head gasket. Head gasket was intact. Head showed signs of running, slight buildup brown carmelized color. Rotated and everything turned smoothly.

Put it back together. Adjusted the valves. Intake is around .006 and exh is around .007. The specs on the sheet said .004 to .008, i split the diff.

Has much better compression now. A stronger "backfire" too. Still not starting.

Ran a meter across the coil, magneto, idk what you'd call it. It measured at 5.78k ohm from plug boot to body. From what I could look up that's out of spec for this engine. 2-5k was the range listed. Not sure how much variance out of spec I can get away with.

That would give me a weaker spark, but enough to not start? I don't mind spending the 35 bucks. But Id really like to not have to throw money on a barely used motor if it's not needed.
 

Last edited by Thered239; 01-11-16 at 12:47 PM. Reason: Fat fingers
  #13  
Old 01-11-16, 12:48 PM
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How was the head gasket?
Valve clearance?
 
  #14  
Old 01-11-16, 02:00 PM
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There should be no sealant used on the head gasket. Whether that is an issue or not....???
Most specs I have seen call for valves to be set .004- .006, I usually set to .005.
Did you physically remove the flywheel to check the shear key?
I would be interested in a compression test also.
With the valve cover removed, rotate the engine and note the movement of each valve and rocker.

With out hands/eyes on, this can be difficult to tell exactly what is going on.
Even a weak or failed coil/mag should not cause the symptoms you state, and IME, any test is not always confirmation, but sounds like yours tests within spec. (I think 2k-10k is the norm)
 
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