1977 B&S 8 hp 190402 weak spark, no start

[jniolon]

Hi folks..... haven't been around in a while.... all my stuff has been working !!! till now !

I've got a 1977 Sears tiller with a B&S 8 hp engine Mod 190402 type 0858 code 77010310 that has been sitting up for several years... decided to get it running for a project... so far... new carb, fresh gas, new fuel filter, new spark plug... carb is getting fuel... it will run out choke tube when choking too long.

it had previously been converted to solid state ignition, points/condenser removed... think it is a NOVA unit or MegaSpark. I've adjusted the coil gap to .010. cleaned the coil posts and the magnet on the flywheel... new shear pin(flywheel key).

engine turns over fine...good compression, but when grounding spark plug I see a very weak white spark... do the solid state modules go bad ??? I tried turning it with electric drill with plug grounded... it fires regularly but weakly...

suggestions ???

thanks
John

 

[reynoldston]

Sounds like the coil is going bad.

 

[mechanic mark]

https://www.briggsandstratton.com/us/en/support/manuals/results?NTT=190402-0858* manual & parts list, check air filter for replacement.

 

[Rivets]

I have to agree with reynoldston, coil going bad.

 

[jniolon]

new coil... new ign module.... tearing up ground again... thanks guys

john

 

[jniolon]

well, I spoke too soon.....

playing with tiller today and it's having some fuel issues... started cold with choke and after a few seconds opened choke. engine at 1/2 throttle it would run about 30 seconds then die... have to start it again with choke... same thing again...

I initially set the main jet at 1-1/2-2 turns and the upper screw (mixture screw ??) at 1 turn... can't get to to run long enough to do any adjusting... without running it on full choke which tells me it's not getting enough fuel.

new plug, new coil and ign module, new carb... the only change was I added a fuel cutoff to the fuel line today... could that be the culprit ??? not allowing enough fuel to the carb ???

help ??

john

 

[reynoldston]

Could your carburetor pick up some dirt. Being a new carb all it should need is cleaning. Also make sure you don't have a vacuum leak at where the manifold fastens to the block. I take a flat block with sandpaper to true up the manifold myself when I work on that engine.

 

[jniolon]

thanks for the reply Reynolds...

carb came in a seal plastic bag and I didn't take it out until I bolted it onto the intake (with a new gasket) the intake was never removed from the block but I imagine i might have a leak there... something to check As far as I know the bolts that hold it onto the block have never been loosened or at least in the last 30 years

I"ll check for the vacuum leak this week and see what that offers.. what about the initial carb adjustments ??? was I close enough that it should run if I don't have another problem lurking ??

thanks
John

 

[reynoldston]

As rule if it will run lower speeds but not high speed it can be lacking a good fuel flow or a plugged muffler. It sounds to me it just doesn't run at any speed to the point you can't adjust the carburetor. It sounds like it could be leaking vacuum or you might of picked up dirt or water some place? You are using fresh fuel right? Seeing it dose run with the choke on it just seems to be a fuel problem..