Honda GX240 Will Not Start After Replacing Carb

[a3fins]

Hello,

Not sure how this happened but I need some suggestions on a Honda GX240. It was surging. Instead of rebuilding/cleaning the carb (engine is about 18 years old) I bought an OEM carb from JacksSmallEngine.com. I replaced the carb and the gaskets, replaced the fuel filter, put in an OEM spark plug. I go to start it up and nothing. It’s getting a spark. I tried starter fluid, and nothing. I put a little gas in the cylinder head and nothing. I checked the compression and it doesn’t even hit 50 PSI. I understand it should get 120 PSI. I took the valve cover off and both valves are moving, neither is stuck. What the heck is going on with it. I cannot figure it out.

 

[Joe Kidd]

Got oil in it? Doesn't hurt to ask.

 

[farminkarman]

Hello,

Not sure how this happened but I need some suggestions on a Honda GX240. It was surging. Instead of rebuilding/cleaning the carb (engine is about 18 years old) I bought an OEM carb from JacksSmallEngine.com. I replaced the carb and the gaskets, replaced the fuel filter, put in an OEM spark plug. I go to start it up and nothing. It’s getting a spark. I tried starter fluid, and nothing. I put a little gas in the cylinder head and nothing. I checked the compression and it doesn’t even hit 50 PSI. I understand it should get 120 PSI. I took the valve cover off and both valves are moving, neither is stuck. What the heck is going on with it. I cannot figure it out.

Who told you that you should get 120psi? Those have an automatic compression release to make starting easier. If you disable the ACR, I would say 120 would be in the right range. I haven’t had it happen on a Honda or Chonda, but I have had the compression release mechanism hang up on a couple Kohler engines. It made them very difficult to get running.

 

[a3fins]

Who told you that you should get 120psi? Those have an automatic compression release to make starting easier. If you disable the ACR, I would say 120 would be in the right range. I haven’t had it happen on a Honda or Chonda, but I have had the compression release mechanism hang up on a couple Kohler engines. It made them very difficult to get running.

Oh did not know that. It has a compression ratio of 8.5:1, and since I do not know my "Gazinta" I google the ratio and it stated 120

How do you disable the ACR

Honda Engines | GX240 4-Stroke Engine | Features, Specs, and Model Info

Official specs and features for the Honda GX240 small engine. The GX240 is a small four-stroke gas engine offering superior performance and reliability.

engines.honda.com

 

[farminkarman]

Oh did not know that. It has a compression ratio of 8.5:1, and since I do not know my "Gazinta" I google the ratio and it stated 120

How do you disable the ACR

Honda Engines | GX240 4-Stroke Engine | Features, Specs, and Model Info

Official specs and features for the Honda GX240 small engine. The GX240 is a small four-stroke gas engine offering superior performance and reliability.

engines.honda.com

The only way to truly disable the ACR would require removing the mechanism from the camshaft. You could probably set your exhaust valve lash really large and mostly negate the ACR. If you are just trying to determine if you have a stuck ring or valve, then do a leak down test.

 

[huskihl]

Unplug the low oil sensor and the switch. I have 8 of these and the oil level sensor gets dirty or goes bad. Even with the oil at the proper level some of them will fire once or twice and then die.

For what it’s worth, if this happens to another one of your Hondas, dump several ounces of Seafoam in with a half inch of gas in the bottom of the tank and choke it with the engine revved up for a couple minutes. Let it sit for at least a month and it will be fixed. Some will call it snake oil, but it has worked on all 5 of the 7 that started loping like yours

 

[a3fins]

Unplug the low oil sensor and the switch. I have 8 of these and the oil level sensor gets dirty or goes bad. Even with the oil at the proper level some of them will fire once or twice and then die.

For what it’s worth, if this happens to another one of your Hondas, dump several ounces of Seafoam in with a half inch of gas in the bottom of the tank and choke it with the engine revved up for a couple minutes. Let it sit for at least a month and it will be fixed. Some will call it snake oil, but it has worked on all 5 of the 7 that started loping like yours

I already unplugged the oil sensor, but not the switch. I'll try that next. Thanks

 

[erikb]

You said the valves are moving, did you check the clearance ? If they are too tight it will give the low compression reading.
.004" on both valves is ok.

 

[RCBS]

Will it bark with a sniff? Does it attempt to fire at all?

 

[Hinerman]

Unplug the low oil sensor and the switch. I have 8 of these and the oil level sensor gets dirty or goes bad. Even with the oil at the proper level some of them will fire once or twice and then die.

For what it’s worth, if this happens to another one of your Hondas, dump several ounces of Seafoam in with a half inch of gas in the bottom of the tank and choke it with the engine revved up for a couple minutes. Let it sit for at least a month and it will be fixed. Some will call it snake oil, but it has worked on all 5 of the 7 that started loping like yours

Do you use seafoam in your saw gas? Do you use it in your straight gas? I used to do both, but don't anymore; not for any specific reason, just stopped using it.

 

[huskihl]

Do you use seafoam in your saw gas? Do you use it in your straight gas? I used to do both, but don't anymore; not for any specific reason, just stopped using it.

Same here. I used to dump a little bit in the big cans just so everything always got a little bit of it. I forget more often than not. But it does work great to clean carburetors that have sh!t in them. Particularly small GX Hondas