Husqvarna LGT 24K54 - engine keeps cutting out when not choked

[jpilk99]

Hi all.

I think I left part of my brain somewhere and can't find it. I've repaired 100s of small engine machines over the years, mostly resolving poor running conditions due to bad/dirty carbs. So when my dear Husqy riding lawn mower, with a 24horse twin Kawasaki engine, just up & quit the other day ...at first I thought I was out of gas. Filled her up and it wouldn't stay running. If I pull the choke, it's starts right up - but 3 seconds after turning off choke, it dies. If I quickly pull the choke again, it perks right up. Turn off choke, it dies after 2 or 3 seconds.

So I figured I must've sucked in some piece of crud into the carb. Took carb off, bowl looked pretty darned clean. Unscrewed the ...main jet (in the middle - sorry my terminology is not great) and it was darned clean as well. Ran a carb cleaner brush up through it, hit it with carb cleaner, then canned air to blow it out. Then went into the "tube" that the main jet came out of and shot carb cleaner and poked into it with a thin guage wire. A little more carb cleaner and air; and then put the main jet back in. Un hinged the float, (inspected - no cracks or anything), removed the needle - rubber tip looked good/sharp. Confirmed there wasn't a rubber washer/seat in the ...primary jet and then gave it a few blasts of carb cleaner and air, then poked with wire. Made sure fuel inlet was clean, sprayed a bit more carb cleaner and canned air, then put it back together.

Same issue.

Replaced fuel pump, (which I don't think was the issue - as it starts and runs, on choke - and I disconnected the fuel hose to the carb and cranked engine and gas pumped out). Still same issue. Replaced fuel line between carb and pump, pump and filter and the breaker line to the block.

Still same issue.

With the hood off the engine, I can see - after starting it and turning off choke, that right as it begins to die, the governor is opening the throttle to full open.... then it dies.

What am I missing?

 

[CalG]

I can't say anything about your engine for sure, but......

The neighbor's Simplicity rider with a vertical shaft V-twin engine was doing the same thing as you describe. Only ran under choke.
He admitts to having no mechanical or diagnostic skills, so I offered to have a look, thinking it had to be fuel delivery.
With the carb removed and dissasembled on the bench, I noticed a couple of "extra" drillings in the bottom of the float bowl. Looking at the outside, I noted an electrical spade terminal . Something new and different to me.

Dang thing has a solenoid fuel cut off InSIDE THE CARB.

I checked the operation by applying 12v to the terminal. NOTHING! Not a click or any movement.
The multi meter was connected, it showed an open.

I jamed a wooden toothpick in the plunger, knowing it would swell with fuel wetting, and really hold that plunger solidly open. Reassembled the carb and told the neighbor to see about getting a replacement fuel cut off solenoid. He hasn't done that yet, but he did mow his lawn today. As he has for the past month since the fix went in.

So check to see if your carb has an electrical wire or connection in the floatbowl. If so, that may be the trouble.

 

[jpilk99]

I can't say anything about your engine for sure, but......

The neighbor's Simplicity rider with a vertical shaft V-twin engine was doing the same thing as you describe. Only ran under choke.
He admitts to having no mechanical or diagnostic skills, so I offered to have a look, thinking it had to be fuel delivery.
With the carb removed and dissasembled on the bench, I noticed a couple of "extra" drillings in the bottom of the float bowl. Looking at the outside, I noted an electrical spade terminal . Something new and different to me.

Dang thing has a solenoid fuel cut off InSIDE THE CARB.

I checked the operation by applying 12v to the terminal. NOTHING! Not a click or any movement.
The multi meter was connected, it showed an open.

I jamed a wooden toothpick in the plunger, knowing it would swell with fuel wetting, and really hold that plunger solidly open. Reassembled the carb and told the neighbor to see about getting a replacement fuel cut off solenoid. He hasn't done that yet, but he did mow his lawn today. As he has for the past month since the fix went in.

So check to see if your carb has an electrical wire or connection in the floatbowl. If so, that may be the trouble.

Hilarious, (in that I wondered about the solenoid that is absatively under my bowl), but assumed that couldn't/wouldn't be it because it runs ...on choke. I thought the solenoid was an "all or nothing", in that by actuating up and into the main jet(?) - that center tube, that it was cutting off fuel flow and that if it wasn't actuated, fuel would be allowed to flow up into main jet. I didn't think the solenoid would fluctuate up and down based on what the choke was doing.

Can the machine run, with choke on, and solenoid not working correctly?

Not sure I follow your tooth pick logic. (My limitation, not yours!!). Did you stick the tooth pick into the ...arm that the solenoid either protrudes up or sucks in?? What is the solenoid supposed to be doing when operating properly??

Thank you!!!

 

[oldnslo]

Solenoid operating correctly it pulls the plunger in allowing full gas flow into the main jet. If not pulling in it will restrict or block the gas flow.

I believe Cal used a tooth pick to wedge the plunger in the pulled in or full open position.

 

[jpilk99]

Solenoid operating correctly it pulls the plunger in allowing full gas flow into the main jet. If not pulling in it will restrict or block the gas flow.

I believe Cal used a tooth pick to wedge the plunger in the pulled in or full open position.

That makes sense, or at least my notion that the solenoid was not pulling in, then out, then in etc. based on the choke. I'm assuming, with the solenoid "not" sucked in, still allowed enough gas to flow up into main jet when the choke door was closed because there was that much more suction going through the carb. With the choke off, and the solenoid still out, there was not enough suction to overcome the solenoid and allow fuel up into venturi...

Regardless, I ordered a new solenoid!!!! Thanks ALL

 

[CalG]

Solenoid operating correctly it pulls the plunger in allowing full gas flow into the main jet. If not pulling in it will restrict or block the gas flow.

I believe Cal used a tooth pick to wedge the plunger in the pulled in or full open position.

You got it !

The wedge holds the solenoid plunger retracted into the solenoid body, just as if the electrical energy were drawing the plunger in.

The plunger "needle" has a poor mating surface and no elastomer seal, so even when "shut off" it still leaks fuel into the emulsion tube. Wth the choke closed, there is a lot of suction going on to lift fuel into the engine.

But then, it could be something else.

Fortunately, that fuel cut off solenoid can be removed WITHOUT removing the carb (at least on the Simplicity) Just pinch the fuel line if you do.

eta

A touch of that shut off needle tip to a grind wheel to spoil any chance of restricting fuel flow would prove out the diagnosis in the time it takes to r&r the solenoid. I didn't do that, cause it was not my machine ;-)

 

[jpilk99]

Well, tested old solenoid - it's working fine. Bought new one, installed, same exact issue. Must be carb?

 

[gstrom99]

Did you try unscrewing the fuel tank cap?, they can plug and prevent good fuel flow. Carbs are a pretty simple device, really. You still must have a blockage in there somewhere. Take it apart again for a good looksee, or buy a new one (if they're cheap enough).

 

[jpilk99]

Carbs are a pretty simple device, really. You still must have a blockage in there somewhere. Take it apart again for a good looksee, or buy a new one (if they're cheap enough).

Agreed. And I already took it apart and cleaned everything I could. Oddly, can't get the Main Nozzle out. It goes up from the Main Jet, up into the venturi, and continues up into the "roof" of the venturi tube. Usually you can reach in with a screwdriver and press down on the protruding nozzle and work it out. This one... maybe I have to grab it with pliers and force it down and out. But agreed, that's 99% sure where the issue is.

 

[oldnslo]

Have you confirmed good spark and compression when hot? I would check those items since you have been through the carb. I believe Kawasaki has individual spark units so one cylinder can get weak spark when hot.