Honda GX630

Welcome aboard. What's a wheelie bin?

Don't know about the Honda's but my 23 HP Vanguards are wired to kill the spark for both cylinders at exactly the same time. If the Hondas are like that there should be a wire between the coils for that. I had one connection that was frayed and the wire was barely hanging on. It broke off when replacing a coil on the VG in my 420. If things got jostled around a bit replacing yours that might cause a shut down issue, like one coil grounding out first and then the other one after a delay. So you might be running on one cylinder when you shut it down until the 2nd coil is grounded. Or maybe the 2nd coil doesn't get grounded at all and the engine just quits at that point. It would likely sputter when it shuts down if that's what's happening. I don't see how a bad grounding wire would affect the gas mileage though. Is it running rough too?

This is what the VG coil wiring looks like.

Good point Mike. I didn't think of that. I also didn't explain what I was talking about very well. I should have mentioned there's a relay to kill the juice to both coils at the same time, on my VG's anyway. If the Honda twins have that feature and the wiring for it was inadvertently jostled a bit installing the new coil, it could be that only one coil is actually being grounded now. Then the engine quits because it doesn't like running on one cylinder.

The VG in my 420 is like that. I had a spark tester on a plug wire one day and the prod slipped out of the plug wire connector in the boot. The engine was idling at the time and it quit after a few seconds when that plug stopped firing and the RPM dropped. It chugged a bit shutting down too, similar to what happens when an engine idle is set too low. I have my gator wannabe set up like that. It's a Honda single cyl and I have the idle set so low the engine quits after only a few seconds if I get completely off the gas. It's intentional. The fwd/rev transaxle doesn't shift very well if the idle is too high. So what I do is get off the gas and flip the shift lever just before it quits then get right back on the gas. It's also handy if I'm getting on and off picking up branches or whatever. The switch to ground the coil is still in the ON position when I get back on the cart so I just have to hit the separate starter switch for the starter/generator and away I go.

Mike_U said:

I'm assuming the engine is connected to a pressure washer pump with an unloader valve that lessens load on the engine when you are not spraying water?

Does that engine have a fuel shutoff solenoid in the fuel line or maybe an electric fuel pump? If the magnetos are not grounding out and shutting off spark, but the solenoid or fuel pump is shutting off fuel, the engine may run until the carb runs out of fuel.

As Army says, check the wiring going to the magnetos to make sure the magnetos ground out when the shut off switch is in the OFF position.

As for fuel consumption, is the unloader valve inoperative putting load on the engine at all times?

Click to expand...

One of my K532's isn't in use now but when it was I had a gas shutoff just before the carb because it would not quit using the key without dieseling. Sometimes pretty bad. I tried 2 known to be good fuel solenoids on it but no cigar. It was a bit annoying to shut it off that way but not nearly as aggravating as the chugging, pinging and death rattle noises. I actually shortened the hose as much as I could between the carb and shut off after this pic was taken. Took too long to quit otherwise. I had to remember to switch the key off after it quit but the 12V pump was good at notifying me the key was on. I inadvertently left it in the ON position one day and the pump clicked away for several hours before I caught it. Didn't cause any harm though. That was about 10 years ago and pump is still on that 400 and working fine.