Briggs and Stratton 550E not starting

dhes

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Hi All,

I am having problems with a Husqvarna LC 146S (2016) mower with Briggs and Stratton 550E Series engine (Serial No: 14 1125 51 8372).

The mower tries to start and might run for a couple of seconds on idle (low revs) and cut out sometimes with a backfire. The last thing I did was check the valve clearance and set to 0.15mm (6/1000 inch) as recommend on YT video. The mower will not fire now that I have changed the clearances. I am at a loss not on what else to do as I have tried everything I found through watching repair videos on YT.

Here is what I tried so far in order:

1. Removed carb and cleaned jets.
2. Removed spark plug and checked for ignition spark (ok)
3. Cleaned around the kill switch and checked for continuity. Kill switch appears to be working as no spark on plug when switch in closed position.
4. Adjusted gap between flywheel and coil which was rubbing in spots.
5. Checked oil leavl and noticed it was over filled. Took some oil out of engine.
5. Double checked the carb to ensure jets are clean
6. Removed flywheel and checked the key/pin was ok.
7. Checked compression by pulling blade in clockwise direction. It doesnt spin freely and does bounce back at certain parts of the cycle. I can hear compressed air been expelled through the air filer which is currently removed.

At this point the mower was trying to start once every 5 - 10 pulls. It might run on very low revs for 1 - 3 seconds and cut out. Poured petrol directly into spark plug hole to see if it might help but didnt make much difference. Noticed when I removed spark plug it was wet and the fuel was blackish colour. I assume this is remaining oil residue in the engine from over filling.

8. Set valve clearances to 0.15mm. I checked before adjusting and 0.15mm gauge was very tight. It was probably set to 0.1mm previously on the exhaust (top valve) and inlet valve (bottom) had wider gap.

Mower doesn't try to start now. It might give a small backfire after pulling cord.

i am at a loss what else to try. The only other thing I can think about is the automatic choke not working. The spring and cable are all connected and it moves freely.

Any help would be appreciated.
 

ILENGINE

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Lets back up and remove the spark plug and the valve cover. Rotate the flywheel until the piston is at the top of the stroke by either viewing with a light, or by putting a pencil in the spark plug hole, Make sure both valves are closed. If one is open rotate the flywheel one complete revolution. After both valves are closed then rotate the flywheel just slightly clockwise to move the piston down about 1/4 inch, and then check and set the valve clearances.
 

dhes

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Thanks for reply.

I checked the valve clearance using the method you described and still no joy. I posted video here of trying to start it. It almost ran one time.

I'm wondering if I am using the correct valve clearance as it was slightly better before I adjusted them.

One other thing - are the pins that hold the valve in place meant to be loose when pistol is in top position?
 
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ILENGINE

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What pins are you talking about being loose at TDC, Are you talking about the push rods or the valves stem itself, or the rocker arms being loose.

Looks like valve clearances are .004-.006 for both valves. Air gap on the ignition coil is .006-.014, and the spark plug gap is .020. How fresh is the fuel that you are using. The new Briggs OHV push engines are very picky when it comes to fuel quality.
 

Rivets

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When you cleaned the carb, did you remove the jet assembly (while part you see when you remove the float bowl)? There are two jets in this assembly and they love to plug up when fuel is left in the float bowl for more than 30 days.
 

dhes

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What pins are you talking about being loose at TDC, Are you talking about the push rods or the valves stem itself, or the rocker arms being loose.

Looks like valve clearances are .004-.006 for both valves. Air gap on the ignition coil is .006-.014, and the spark plug gap is .020. How fresh is the fuel that you are using. The new Briggs OHV push engines are very picky when it comes to fuel quality.
I was talking about the push rods (opposite the valve) and rocker arm. Looking at other videos this seems to be the norn where you can move the rocker arm about.

Valve clearance .004-.006. I assume that is in inch. 0.006 inch = .0.15mm by my calculations.

I used a business card to adjust the coil but will reset that tomorrow using gauge.

Fuel was bought a few weeks ago so should be ok.
 
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dhes

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When you cleaned the carb, did you remove the jet assembly (while part you see when you remove the float bowl)? There are two jets in this assembly and they love to plug up when fuel is left in the float bowl for more than 30 days.

Yes I removed the white plastic part with the jets and split that into two parts also. I could see through both jets and put wire through just to be sure. I used some WD40 for blowing through. There is another part that looks like a jet on the assembley but that appears to be blocked off.

Ive seen another video where they drilled out the jet to improve fuel flow.
 

dhes

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How do I test the automatic choke to make sure it is working?

I assume the choke is in open position when first started and closes as engine warms up?
 
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ILENGINE

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It looked like you were pressing a primer bulb in the center of the air cleaner in your video. If true then you don't have a choke.
 

Rivets

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I happen to have one of those carbs at home and just took it apart. The white jet assembly is not designed to come apart. The horizontal jet is your main jet and the vertical one is your Venturi nozzle. If you split the assembly into two pieces you probably broke the integrity of the assembly which is why it is not working. As IL said if you are priming there is no choke.
 
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