Newbie looking for help with Honda GX240 that won't run

[PDX Man]

I don't think you have done any damage starting with wot,

It's when your trying to work out what's wrong, it's 1 or another equation that needs to be eliminated.

An engine needs spark, air, fuel, compression

I still think It's fuel starvation, get a spray bottle and spray fuel in the carb while it's running, and try and open the throttle.
This way your providing the fuel and opening the throttle provides the air. And you have a spark because it starts and runs a bit.
It may run rough, but as soon as you stop spraying fuel, if it dies then it's fuel starvation.
If you watched the vids I linked, the 1st one shows him dumping x amount of fuel in the air intake. This is what I would do to get the engine started, which saves pulling the cord and saves my arm, by spraying you can see/hear every time you spray the engine should Rev up. If it don't then fuel is not the problem.
Anyhow, it's up to you to try, and if it don't work it must be something other than fuel.

And/or you can do it with the other AM carb,

If you can keep it running by providing the fuel from a spray bottle , that indicates not enought fuel from the carb,
The only othe thing I can say is change the spark plug for a known working one or test the plug in another machine,
Cheers

I don't think you linked the video you think you did. They both do some basic diagnostics and then mainly focus on a cursory cleaning of the carb. I didn't see any dumping of fuel in the air intake.

 

[PDX Man]

WOT at start just floods the spark plug. what I will say is put a new spark plug in it. Ill bet the plug when it gets some temp its shorting out not as( common ) as carb problems or no spark. but we know the engine will idle for a short time or till you put gas to it. Did you adjust the polit screw 2 turns out from bottom? that will put you in the ball park and go from there. if the spark plug does not take care of it Ill eat crow because the only thing that would be left in the electrical sys is the trigger circuit in the coil and temp will do the same as spark plug.

I put a new spark plug at the beginning of diagnosing this, mentioned in my original post. Before I posted the original post, I tried the things I knew how to do and not make anything worse - new sparkplug, fuel filter, fuel line, new chinese carb, make sure air filter not clogged, check gas cap venting. I haven't touched the pilot screw or any other adjustment yet., but it was operating before at the current settings. I can do that as one of the next steps, I was hoping to do the spray fuel test suggested by Wonkydonkey first.

 

[Wonkydonkey]

The 1st vid, @ 3:53 he dumps the fuel in the air intake (although you can't see it as its behind the exshust) which came from the carb that he drained.
Notice how the engine rev'd and died, he also said in the begining about the throttle being open WOT at startup, generators start like this, it's the Rev limiter that controls the speed of revs.

Cheers

 

[PDX Man]

Yeah, put up a video, if you can. Try and start it with the valve cover off too.

Here is a video of the rocker arm movement while pulling the starter rope. Spark plug disconnected.

And a video of the rocker arms with engine running. Only the first 37 seconds is usefull. I couldn't get youtube to trim the video.

 

[PDX Man]

The 1st vid, @ 3:53 he dumps the fuel in the air intake (although you can't see it as its behind the exshust) which came from the carb that he drained.
Notice how the engine rev'd and died, he also said in the begining about the throttle being open WOT at startup, generators start like this, it's the Rev limiter that controls the speed of revs.

Cheers

OK, all he says there is he is trying to start and I didn't see what he was doing. So I collected some fuel. In the fhe first video I started the engine on idle, it started up. I dumped fuel into the air intake. I'm not sure how much made it in, a lot spilled on the outside. The engine died, but I'm not sure it had anything to do with putting in the fuel. The second video I dumped the fuel in first and tried to start. It wouldn't start at all.

 

[woodtool89]

when you "cleaned" the main jet and the nozzle, did you make sure all holes were not plugged with varnish?
did you pull the mixture screw out yet and clean it and the seat? if not, don't worry about adjusting it, its easy...screw it back in until it stops, then ~1.5-2 turns out, then adjust as needed while its running
a lot of time carb cleaner isn't enough to clean everything, small piece of wire and compressed air is needed to clear blocked passages...
everything is pointing to fuel delivery!

 

[Fish]

No, I don't think that it is the carb. If you were to turn off the fuel, and then
pour a trickle in, after a few pulls, it should start and run great until that fuel squirt is burned off, if the engine was healthy.

 

[woodtool89]

No, I don't think that it is the carb. If you were to turn off the fuel, and then
pour a trickle in, after a few pulls, it should start and run great until that fuel squirt is burned off, if the engine was healthy.

he poured a frickin jar of gas into the intake, not no trickle...it flooded the cylinder...
this thread is just pitiful

 

[Wonkydonkey]

It seems to me that dumping the fuel in the carb (your 1st vid) the engine rev'd more than it has ever done in the other vids. Yes it died cos the fuel got used up.


But it's easy to dump to much and flood it (2nd vid) and as you may have noticed it takes a bit oftime for the fuel to get there.
Like @woodtool89 says you need to clean the carb as in the second vid I posted not just carb cleaner!, and we don't have a sonic bath, so a bit of wire is what we have to use
I still think the problem is fuel starvation.


Cheers

 

[Fish]

Even if the engine got flooded, once cleared out, the engine should run several seconds at full rpms until the fuel is burned off, on a healthy engine. It does not behave like an engine with a simple fuel starvation problem.

 

[Wonkydonkey]

Even if the engine got flooded, once cleared out, the engine should run several seconds at full rpms until the fuel is burned off, on a healthy engine. It does not behave like an engine with a simple fuel starvation problem.

Throttle position ?

A generator engine is Wot, then when engine starts the Rev gov takes care of the throttle and keeps the Revs constant with or with out a load on the engine.

This engine has a varable throttle, with a Rev gov.

So if it's started with some fuel poured into the air intake, and the throttle is wide open, then it should do the same as the first vid I linked to. As it would be getting enough air to burn the fuel, but the throttle was not wide open.....

Also the engine was started with choke and run a bit first. This is fine as it warms the engine up a bit.
to test the fuel starvation theory... I would WOT and then put some fuel in the air intake and the start with out choke....just like the 1st vid it may take more than one Atempt you may flood it. but once it starts Then the revs should increase till the fuel was burnt.. And by spraying fuel in it helps as it is in smaller amounts and will burn easly , and also remember there is a bit of a lag till it gets into the cylinder but you can keep spraying

Anyhow this is what I think it is and how I would check.

I do hope the op finds the fault whatever it is.
Cheers

 

[PDX Man]

when you "cleaned" the main jet and the nozzle, did you make sure all holes were not plugged with varnish?
did you pull the mixture screw out yet and clean it and the seat? if not, don't worry about adjusting it, its easy...screw it back in until it stops, then ~1.5-2 turns out, then adjust as needed while its running
a lot of time carb cleaner isn't enough to clean everything, small piece of wire and compressed air is needed to clear blocked passages...
everything is pointing to fuel delivery!

Yes, I cleaned the main jet with carb cleaner, ran piano wire through the openings and then compressed air. And visually checked that I could see through all the holes. Well actually I visually checked before cleaning as well and I didn't see any blockages. I will try cleaning the mixture screw and other areas that I could have missed in the carb right after I try the spray bottle test that Wonkydonkey has suggested.

 

[PDX Man]

Throttle position ?

A generator engine is Wot, then when engine starts the Rev gov takes care of the throttle and keeps the Revs constant with or with out a load on the engine.

This engine has a varable throttle, with a Rev gov.

So if it's started with some fuel poured into the air intake, and the throttle is wide open, then it should do the same as the first vid I linked to. As it would be getting enough air to burn the fuel, but the throttle was not wide open.....

Also the engine was started with choke and run a bit first. This is fine as it warms the engine up a bit.
to test the fuel starvation theory... I would WOT and then put some fuel in the air intake and the start with out choke....just like the 1st vid it may take more than one Atempt you may flood it. but once it starts Then the revs should increase till the fuel was burnt.. And by spraying fuel in it helps as it is in smaller amounts and will burn easly , and also remember there is a bit of a lag till it gets into the cylinder but you can keep spraying

Anyhow this is what I think it is and how I would check.

I do hope the op finds the fault whatever it is.
Cheers

OK, I tried the spray bottle and I think the results are a bit more clear than my attempt ar dumping fuel in. The throttle was wide open, the choke was open, the fuel flow was open (not sure if that was how you wanted to see it. Since it doesn't want to run with the throttle open, it was tricky to get fuel sprayed in before it died. The first couple of attempts, I didn't get the fuel in before it died. The best attempt is at the end of the video, where I think it shows what you want to see. While trying this, there was a lot of backfiring and even flames coming out of the intake. Is this expected for what I was doing or does it tell us something about the problem?

 

[Fish]

Looks like a valve or timing problem.

 

[woodtool89]

Looks like a valve or timing problem.

I'm still on a carb issue...
I cant see a valve problem as it ran fine the last time he used it...mechanical issues don't usually arise when its not being used.
timing though...possible sheared key in the flywheel...I doubt it though, as they usually wont run at all...

 

[Wonkydonkey]

So now the carb is clean, and it does not seem'do to have resolved the problem. Does it still tick over a bit with the throttle closed, have you open the fuel mixture screw out 1.5/2 turns.

I don't think its the flywheel key unless you taken the flywheel off and not put it on wrong. But it could be the key ?, it's an elimination process, Is there any rusty deposits in the flywheel magnets
But I'm now thinking it's the coil. Do you get a good spark on the spark plug,
Do you know anyone with a simular engine where you can swap/try your coil. In there engine.
And watch this

This is worth a read,
https://www.smokstak.com/forum/showthread.php?t=72156
They go over simular topics
It says could be spark screen, if you have one,
It says try running with the choke on a a little bit, as this increases the fuel air ratio

Everything I see/read says fuel, carb clean first, then spark/coil timing.

 

[Fish]

Flaming carb? Clean the carb?

It indicates either a spark that is hitting at the wrong time, or an intake valve that is letting the explosion of the combustion process go into the intake area.

 

[Fish]

Here is one with a similar problem.

 

[CR888]

Does this model have a wire mesh spark arrestor in the muffler? A plugged up screen may also give similar symptoms.

 

[Wonkydonkey]

Flaming carb? Clean the carb?

It indicates either a spark that is hitting at the wrong time, or an intake valve that is letting the explosion of the combustion process go into the intake area.

Yep I totaly agree
But the vavle clearance was checked, so that leaves the flywheel key
Or the coil,