Brigss & stratton "ready start system", I'm stumped

[mr.farmall]

B.S. Engine 128m02-1612-f1-12041958 DOM Apr 2012
190 cc Platinum 7.25 on a 22" walk behind mower

I've worked on a lot of engines, but this ones got me stumped!
This engine has a very weak spark when started with starter rope. With a neon tester connected to the spark plug, it barely glow while pulling the rope starter. If you pull it moderately, there is no spark at all. only at the fastest pull will it generate a pulse.
Compression at the spark plug is less than 4 lbs,(It has a compression release built in to the cam wheel), so it' easy to spin over,but the engine will not start with pull rope.
When starter rope is removed and flywheel exposed, using a drill and socket on the flywheel to generate a higher starting speed, the engine will start and run well but only after higher rpm,s than can be generated with pull rope. The spark is great while it is running. Engine runs very well after it is started.
Have serviced carburetor ( that was clean to start with but cleaned it any way), checked valves and lashing, changed out spark plug, changed out Magnetron (coil pack) and set at 10 thousandths inch. Checked 途eady start system ( auto choke mechanism with thermostat on exhaust that interfaces with auto choke), checked all carburetor linkage and governor. These are all functioning correctly.
I suspected a problem with the magnetron coil pack, but Engine runs great with new and old magnetron, once you get it started. Also checked that the kill switch connection is not grounded and it works the same with it connected or disconnected from the Magnetron.
Starting speed of engine is only factor that changes. Once the starting speed is increased, the engine will start and run great, but pull with all my might, I cannot get enough speed to start the engine with the pull rope, let alone someone not as strong or big as I.
I have tried to prime the start with a little gasoline in the carburetor, but it just fouls the spark plug.
I have also pulled the plug after a lot of unproductive pulls with the starter to find the plug moist and fouled with gasoline.
This has been a real problem. What can be done to fix this issue?
Briggs and Stratton have been of no help, only telling me that it take one of their specialist to adjust the ready start system.
One last observance, it take 4-5 seconds of turning with the drill before the first pop of the engine, followed by a couple more hit and misses, then it starts
CONCLUSION:
the magnetron will produce a good spark, but only at rpm,s above about 600-700
The extremely low compression must be ok becuase it runs great once it's started.
If anyone has had experience correcting these symptoms, I would be very thankful for any advice.

 

[lzn197]

Less than 5 lbs. compression? Oh man! I'd focus on that. You've got a compression problem.

 

[EngineMan]

Less than 5 lbs. compression? Oh man! I'd focus on that. You've got a compression problem.

Why don't you read the post again....he say's it has "(It has a compression release built in to the cam wheel)" so it will not have high compression on start..!

 

[lzn197]

Why don't you read the post again....he say's it has "(It has a compression release built in to the cam wheel)" so it will not have high compression on start..!

I did read the post. Engines have had compression release mechanisms for years. 5 Lbs. compression is not enough.

I find it interesting that someone would slam MY comments but add NOTHING to help the guy. :smile:

 

[EngineMan]

You may have poor (low) magnets on the flywheel.

 

[tybilly]

I don't know much about tjose engines,but I have heard they had problems with the coils at one time,but I imagine that they've figured that out,when you swapped coils out .did you clean the mounting post up with sandpaper or a light filing with a file?i was taught corrosion can accumulate at that spot,wich could lead to a weak spark,i have one of tose engines on my pressure washer and im not too impressed with them,especially trying to restart when its hot. a compression test reading wont tell you anything on an ez spin cam,spinning the flywheel backwards and watching it bounce is probably the only test you could do for compression

 

[EngineMan]

I did read the post. Engines have had compression release mechanisms for years. 5 Lbs. compression is not enough.

I find it interesting that someone would slam MY comments but add NOTHING to help the guy. :smile:

Reason why engine's have compression release is to aid the starting, and has for helping him out, I like to check the depth of the water before I jump in.

 

[pugaltitude]

Couple of things to try.

You need a proper spark tester as a neon light does not load a coil as if its under compression related conditions.
forget the colour. Its either sparking or not.

It should have the newer style coil fitted with a blue ring which is a higher voltage output coil only 250RPM to allow spark (going off memory).

That engine will have the newer sparkplug so it will be a Champion RJ19LMC and not RJ19LMR or briggs part number 591868.
It will have to be set to 0.020" instead of 0.030" as it was on the older model.

Other thing to try would be the metal suppressor caps on end of coil let were bad for failing.
Pull the metal cap off and see what happens. Usually that can cause a bad starting issue. Just fit a normal rubber boot and terminal briggs part numbers 493880S and 66538S.

Is you OPC cable allowing the micro switch to pull away from the earth contact when pulling the mowers bail arm?

Is the flywheel key sheared?

This is as long as the ready start system is set up properly with the thermostat and choke lever set correctly.

Good luck:thumbsup:

 

[mr.farmall]

=pugaltitude;147819]Couple of things to try.

Is the flywheel key sheared?

no the fly wheel key is in great shape, it looks like new

That engine will have the newer sparkplug so it will be a Champion RJ19LMC and not RJ19LMR or briggs part number 591868.
It will have to be set to 0.020" instead of 0.030" as it was on the older model.

the original plug is a champion RJ2YXLE and has the B.S. symbol imprinted on it.
I have also tried to use RJ19LM no "R" nor "C" on it. And have tried other plugs that I had. They all seem to work with the same results. I don't know the difference between the RJ19LMC and RJ19LMR and the RJ19LM.

It should have the newer style coil fitted with a blue ring which is a higher voltage output coil only 250RPM to allow spark (going off memory).

Both the old and the new coil I have used look identical and neither one has any blue on it. The new coil part # is 590454. Do you have a part # for the coil with a blue ring?

You need a proper spark tester as a neon light does not load a coil as if its under compression related conditions.
forget the colour. Its either sparking or not.

I don't have a gap tester but I did try putting a second plug in line (series) with the first plug. I was able to vary the plug gap on the test plug, but after I finished, it occurred to me that the 30 /1000 on the installed plug was the limiting factor and changing the test plug gap was meaningless. I'll redo the test again tonight after I change the gap to a close 15/1000 on the installed plug.
The installed plug is under pressure, but the test plug is not. It can at least give me a clue!
One thing I noted was that it started to give a very weak spark at about 250-300 rpms. as the rpms speeded up, the spark became stronger and at 600 rpm's it was a sharp snap and a wide spark, not the narrow, almost invisible spark at 300 rpm's. This is the same results I noticed with the neon tester, a very dull glow at low rpm's to a bright flash at higher rpm's

Other thing to try would be the metal suppressor caps on end of coil let were bad for failing.
Pull the metal cap off and see what happens. Usually that can cause a bad starting issue. Just fit a normal rubber boot and terminal briggs part numbers 493880S and 66538S.

I'm not sure what you are getting to with the caps. Both coils look identical and have no caps by the coil. There is a rubber cap at the plug end of the wire. Ihad to remove the rubber cap to install it on the new coil. I took it apart to have a good look at the connection from the coil wire to the metal plgu that connect to the spark plug. It has a good solid connection and you can see the wire double back under the metal to form a good connection. It's not loose nor does it have any corrosion at all.

Is you OPC cable allowing the micro switch to pull away from the earth contact when pulling the mowers bail arm?

Yes the earth ground is completely gone, I even disconnected it at the magnetron to make double sure.

This is as long as the ready start system is set up properly with the thermostat and choke lever set correctly.

It appears that at a cold start, the thermostat doesn't even come into play. From the Briggs web site, it says that as the engine warms, the thermostat lever moves forward stopping the auto choke from going to the choke position as the engine stops. This prevents a choke with a warm engine. This thermostat is doing just as it was stated from Briggs. But I still have trouble whether the engine is warm or cold.

 

[mr.farmall]

Further testing;
I set up a gap using two screws pointing at each other through the sides of a u shaped piece of nylon. I was able to vary the gap by unscrewing them a little to separate the points. the connection came from the magnetron spark plug lead to one of the screws and then across the air gap to the second screw then to the installed spark plug with a 15/1000's gap on the plug. This was very interesting to watch.
At 15 / 1000's, I got a spark at 250-300 rpm's. it appeared to be very thin, almost needle like, but it was a spark. It looked stronger as the speed increased.
At 76 /1000,s got the same spark at the same rpm's
At 90 / 1000's The same thing. This is almost a 10th of an inch, much wider than any plug would ever be set at!
I got a spark clear up to 150/ 1000's.
Then I changed the installed plug to 40/ 1000's and reset the air gap test to 60/ 1000's
I still got the same results. I think this clears up the issue of whether the Magnetron is bad or not. Definitely not.
But the starting results are still the same. It takes about a 600 rpm for a few second to get it started. A lot more than a pull rope can generate.
Also, I got info on the magnets from the Brigs and Stratton web site to test their strength. It says that with the fly wheel vertical, a 10 inch #3 screwdriver should not fall off when placed horizontal across the magnet.
On this one, the center magnet held very strong, the two outside magnets wouldn't hold a 4 inch screwdriver. I'm not even sure they are magnets, just getting some magnetic attraction from the center magnet.
To verify this, I got another fly wheel from the parts house and tested it. It was identical!
the magnets and the magnetron generate the spark. I'm satisfied that both of mine are in good shape. I now need to look elsewere.
any further ideas would be greatly appreciated.