SV840 erratic engine behavior.

[thee_oddball]

I recently bought a used bad boy sixty inch mower three hundred and eighty nine hours on the motor.

I started It up and test drove and everything was fine but after getting it home and driving it for 10 minutes on my grass It would start to stumble uneventually it would die, I was able to mow the lawn at low RPM for about 10 minutes Before the same behavior would start it would stumble and die but then start right back up.
Thinking the carburetor was just dirty I went and bought an aftermarket 1 off amazon that came complete with the fuelpump and filter aswell.
The spark plugs are new and the gas is fresh after installing the new components. I was greeted with the exact same problem.

Any feedback Would be appreciated.

 

[ILENGINE]

Could be foreign material in the fuel tank that is blocking the fuel outlet and would cause those symptoms. Also the tank not venting properly will cause that issue also.

 

[thee_oddball]

Update and just a quick recap about what's already been done.
.The engine has new spark plugs new coil packs new carburetor new fuel pump New fuel filter new air filter and a fresh change of oil Along with fresh gas.

The guy bought it off came over and we spent about an hour and a 1/2 Working on the engine making sure the coil packs were aligned and working checking to make sure some of the safety switches weren't shorting out.
It seems like we've gotten it fixed until he try to drive over my Wisconsin mound system any time he tried to go up the hill It would try to die but once he got back on level ground It would seem to run okay.

.Any help would greatly be appreciated.

 

[bertsmobile1]

And being a used mower the fuel lines could very well be collapsing as well.
Erratic behaviour is not much of a description
Each type of fault have theri own symptoms
Remember we have nothing to work with but what you type on a screen

 

[thee_oddball]

And being a used mower the fuel lines could very well be collapsing as well.
Erratic behaviour is not much of a description
Each type of fault have theri own symptoms
Remember we have nothing to work with but what you type on a screen

.Thank you for responding and I did type above what we've done so far and the behavior.
It's starting to look like the culprit might be one of the aftermarket coils he put on Because even when it was just sitting there idling I swear I could hear a very faint misfire happening and it only seems to happen under heavy load.
Of course the other option is something I don't want to deal with which would be a blown head gasket.

 

[bertsmobile1]

Sorry,
My bad I read i but it did not register
So we have to start by working out if it is an engine or a mower problem
To do this you remove the kill wires from the coils then go mow
Problem goes away = mower wiring problem
Problem remains = engine or fuel problem
Do that and get back with the results
Note this is for testing only it is not a fix and renders the mower even more dangerous to use than normal
The fuel solenoid on the carb should starve the engine off but if it fails then you will need to pull the spark plugs which can be quite shocking .