I have been having trouble with my B&S 15.5 hp motor model 31R7 07 0033 G1. I had fuel solenoid issues got a new one but it still surged so I got a new carb, no better. I am getting 12.34 v to the solenoid. It wouldn't stay running but I kept starting it and it finally stayed running but would stall and almost die then take off again. I have a video of what its doing but it won't let me attach it. This is on a 2016 Troybilt Pony 42" rider
B&S 15.5 hp surging
- Thread starter dkgroce
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Upload the video to YouTube and paste the link here.
I sprayed starter fluid all around the intake and never heard a change.
bertsmobile1
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This is the problem with trying to diagnose things on the web
That does not sound like surging to me, it is cycling way too quickly.
It really sound like a bad plug or a magneto problem.
Surging happens because the air fuel ratio is too lean to maintain a constant speed
This causes it to slow down so the governor allows the throttle to open up, the sudden gulp of fuel causes the engine to speed up then the governor closes the throttle butterfly to the spot that should allow the engine to run at a constant speed , which it can not because the air: fuel ratio is too lean and the cycle continues .
This is most obvious by looking at the governor arm which will be moving back & forth .
Get an orange in line spark tester and hook it up to the engine.
start the mower then put your finger on the governor to stop it cycling
Slowly increase the speed while watching the tester.
IF the tester does not flash in time with the engine miss you have a wiring / magneto problem
If the tester shows a constant uninterupted glow then change the plug.
On the subject of plugs, what are you using in the engine ?
That does not sound like surging to me, it is cycling way too quickly.
It really sound like a bad plug or a magneto problem.
Surging happens because the air fuel ratio is too lean to maintain a constant speed
This causes it to slow down so the governor allows the throttle to open up, the sudden gulp of fuel causes the engine to speed up then the governor closes the throttle butterfly to the spot that should allow the engine to run at a constant speed , which it can not because the air: fuel ratio is too lean and the cycle continues .
This is most obvious by looking at the governor arm which will be moving back & forth .
Get an orange in line spark tester and hook it up to the engine.
start the mower then put your finger on the governor to stop it cycling
Slowly increase the speed while watching the tester.
IF the tester does not flash in time with the engine miss you have a wiring / magneto problem
If the tester shows a constant uninterupted glow then change the plug.
On the subject of plugs, what are you using in the engine ?
I do not know but it is a new plug exactly like what was in from the factory.
bertsmobile1
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Does not mean it did not foul the instant you started to use it
A photo of the business end of the plug would be helpful
And we still need to know if the governor arm is ossiliating back & forth in time with the engine miss .
A photo of the business end of the plug would be helpful
And we still need to know if the governor arm is ossiliating back & forth in time with the engine miss .
The spark plug looked good last time I had it out, this weekend. No carbon, still clean. I have pics and a video of it "running". The black valve on top is the choke. It does not move unless I move the lever up top. I cycled the motor to low, which you can see and hear. In the end, I had the choke about half on and it smoothed out, you can hear that too. Sounded like low RPM to me but I manually moved the throttle and it revved up. I did have one little problem. See photo. Is that too rusty for the magneto?
