Briggs miss question

[madmixerman]

I have a 16 hp v-twin. At idle through 3/4 throttle it seems to miss or lope. It will do this also when throttling up but when it gets to full throttle it seems to smooth out. I have changed fuel lines ,fuel pump,fuel filter & plugs & air filter is clean. I also run a little SeaFoam in the gas periodically . Wandering if it could be the coil ? Engine is a 2000 year model.

Model 303777
Type 1147-E1
Code 99071411

 

[Tinkerer200]

Well if you suspect the coils, remove the cooling shroud and disconnect the "Kill" wire from the base of each of the two coils. These engines have a Kill Wire system which contains Diodes. IF there is a problem with one of them it causes weird problems. Don't run the engine without the cooling shroud.

Walt Conner

 

[madmixerman]

Pulled both plugs today. Both were replaced last year. One plug looks like it is burning properly & the other is all sooty black but not wet. I assume this means it was burning rich in that cylinder. If my assumption is correct ;how can one cylinder burn properly & the other rich?

 

[mechanic mark]

http://rich.homeunix.com/gravely/pro16/272144 Vanguard Twin Cylinder OHV BRIGGS & STRATTON.pdf

see section 1 page 23 for valve adjustment, both intake & exhaust valves for each cylinder should be closed & rocker arms loose, this will let you know engine is on correct stroke

 

[sidemouse]

1. Does it have fuel in the tank?
2. Is the fuel shut-off valve completely open, if so is there another one?

With the engine off...
I would disconnect one spark plug wire and see if it starts, sputters, fires, anything...
If it does, shut it off, rehook that wire and unhook the other.
Repeat.

If it runs/sputters/fires on either plug it's not the coils.

If it doesn't run/sputter/fire at all on one or the other then the bad coil is the one that's hooked up.

The other possibility...
Could be a leak in the PCV hose, if it has it.

 

[bertsmobile1]

New plugs then do as Walt instructed.
If one coil is not firing properly that side can foul the plug.
Fouled plugs are worse at low speeds.