OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Honda Engines Honda GV150 lawnmower

Hi ALL.
I'd like to ask someone to help with sorting out problems with Honda GV150 engine.The problem start one day.Very hard to start;shaking while running on idle sped and stoping;blow black smoke;back firing;
and finaly now no spark and no start.I've clean spark plug,and carburator.When I take spark plug is wet and black.

I have change the oil ,changed the petrol and it starts then splutters and runs rough too rough to mow anything !

have taken out the spark plug and cleaned each time only to have the same problem again.
I think its the air fuel mixture but dont knwo how to change or could be totally wrong.
Please if you can help me what to do with this problem.

Thank you.

I've moved this thread to the Honda engine forum.

The first step is to establish whether you have ignition. To do that you need a clean spark plug. Clamp it to the metal cylinder head, connect the spark plug lead to it, set the controls in the start position, and pull the starter cord whilst watching the spark plug gap. If you get a smooth series of blue sparks, your ignition system is OK. Reinstall the spark plug and connect its lead.

If ignition is OK we need to look at the air/fuel mixture. Your symptoms sound as if the engine is running rich - that is, it is adding too much fuel to the air being sucked into the cylinder. To verify this, drain the fuel from the fuel tank and start the engine. If the problem is that the mixture is too rich, it should slowly improve as it lowers the fuel level in the carburetor float bowl, then run properly for a short time, then starve out and stop. If it does all that, tell us and we will have to talk about what might be causing the rich mixture. The most likely problems are either the choke is stuck in the closed position, or the float bowl is flooding due to dirt between the needle and seat, or damage to the float or needle.

perhaps checking the air filter would be another step , poor air flow = rich mixture

Good point ozziejohn, it fits the symptoms. The only reason I didn't incline that way was that the problem developed suddenly - but bad things can happen to air filters suddenly if they get clouted or someone re-oils them with SAE140 oil.

This is a (very) late response to Rodeobob's 2012" GV150 tuneup help needed" post. I found the responses to the post very helpful and thought I'd add my suggestions for the benefit of others trying to tune the carby on this engine.

In my humble opinion the GV150 has a number of poor design features, but putting the fuel mixture screw in an inaccessible position on the engine side of the carby is the worst.

To illustrate, this picture shows accessing the screw directly requires removing the engine cowl (not a trivial job either) and placing a screwdriver through the flywheel cooling fins. I considered holding the screwdriver at an angle to clear the fins but decided against this as chances of breaking a fin (or my fingers!) when the engine was running would be high.



I tried using a flexible shaft screwdriver and even purchased an offset shaft driver but the lack of clearance around the screw prevented either from being used so I made a stubby thumbwheel screwdriver from the offcut of 1 1/2" hole saw I'd cut in a piece of sheet plastic. I jammed a 1/4" phillips head bit into the guide hole and roughed up the circumference to improve traction. (If you don't have a suitable piece of plastic handy, something like 1/4" MDF sheet would work). It was difficult to read the rotation marks from a distance so I drilled a small hole as a reference to see how far the screw was being been rotated.



The next problem is holding the thumb wheel in position while being turned so I drilled a 9/16" hole at the end of a piece of 1/2" aluminum bar and bent the tip ~45 degrees to match the inclination of the mixture screw.



One of the holes in the air filter base plate is almost above the mix screw and I extended the hole to be able to see the mix screw clearly. (This will let in a tad more warm air but I don't think this will be significant plus, the hole extension can always be taped over)



Here's a picture of the thumb wheel held in place.



I could have shortened the holding lever to allow the air filter cover to be replaced but I chose to make a temporary cover out of a piece of MDF. (Tip: invert the plastic cover to mark the bolt hole positions on the MDF).



I set the ignition timing (also a non trivial operation) and then used a wedge to hold the bar in position while I started the engine and rotated the thumbwheel with a long screwdriver from above the muffler. I only had to rotate the wheel though ~ 1/3 of a turn to find the sweet spot.

So, after several hours fabricating special tools, I was able to complete a job that should have been done in minutes if the fuel mix screw had been sensibly placed!