Small Engines (Lawn Mowers, etc.): mtd lawn tractor, blown head gasket, interlock system


Question
QUESTION: Hi. I have an mtd model 13ah762f752 with a briggs 219707-0189-e1. The thing runs great and drives but wont drive and mow at the same time. I can sit with it in neutral with the blades engaged and it runs fine but when i try to start mowing it wants to die. Tried replacing fuel filter because its like its running out of gas but no luck. It has the nikki carb. Suppose it needs rebuilt? Thank You

ANSWER: I am guessing you have an ignition switch that has a "bypass" position on it that allows you to mow in reverse.  If this is the case you will need to replace the ignition switch.  IF this is not the case, look for wires being disconnected by the shift lever (underneath the tractor) as you have some sort of an interlock (safety) system.

There is a single black wire that attaches to the side of the engine somewhere.  This is your ground wire.  Disconnect this wire then try mowing.  If the tractor works fine its an interlock system malfunction as i previously indicated.

DO NOT unplug the wire that leads to the carb.

Let me know what you find!  Happy Tinkering!

---------- FOLLOW-UP ----------

QUESTION: Thanks for the quick reply. I will give it a try, but the thing will mow for 10 feet or so then bog down spit and sputter then pick up and go another 10 feet and bog back down. I can sit still with blades on and the thing will run fine. I am a bit confused with this thing. Thank You.

Answer
Is it smoking?  Could be a blown head gasket?  There is a black wire near where the throttle cable attaches to the engine.  Disconnect this wire and start your engine and see if it makes any difference.  You will need to touch the wire back against the terminal to stop the engine however as this is your kill wire.  Check this and  get back to me.