Lawn Mower Underpowered Fuel Issue?

steve terplak · Jul 4, 2016

Hey guys,
Going to post this on a garden tractor forum too...but this is the best accumulation of knowledge around so I figured I'd check here too.

Have a Cub Cadet 1529 lawn mower that has been acting a little funny this summer. Has a 19.0 hp Kawasaki 2 cyl engine

At first start up, turn key pull choke, engine fires, push choke back in and you are off and running...always been that way...
But now, the engine doesn't seem to get full power, struggles to drive full speed and mow...stinks like gas as it does this.
Shut it down, 15-20 minutes...re-start, same process...runs fine, full power, no issues, smell is gone.

What gives? Saw some gas dripping from a fuel line today, cut it a little shorter (to remove hole), re-crimped it, didn't solve issue...solved dripping fuel...thought maybe I had solved it..line looked pretty cracked...it is the line before the inline filter...

My thought is...a) is there some kind of object in the tank that settles and blocks fuel then loosens up after running? But then why the smell of gas?
Cracked fuel line...air getting in, causing a lack of power when running...but then what happens 20 minutes later when it runs fine?

I am at a loss...should I go ahead and replace line first and see what happens? Is the fuel pump going bad?

Thanks guys'

Steve in VA · Jul 4, 2016

Neighbor's JD had similar symptoms. I was finally able to diagnosis it as a faulty ignition coil on one of the 2 cylinders. Not familiar with the cub but parts shows separate coil of each of the plugs. If you can catch it acting up, try disconnecting a plug wire.

Steve in VA · Jul 4, 2016

Probably should have mentioned that the problem was intermittent.

sotxbill · Jul 4, 2016

2 cyl engines.... on the bs engines.. the valve settings loosen up and a push rod pops off and then it runs on one cyl and the other stinks like gas... I have had to adjust the valve lash several times in the life of my engine....

Then the other day,, heard a piece of junk break loose and then it ran badly... pulled the plastic cover off the top and found out that a piece of crud broke loose, went around the fly wheel and broke a coil mount loose.. so I jb welded it back in place and now I am back to two cyl firing again.

doesnt hurt to look at those.... you can pull a plug wire one at a time to see which cyl is firing and which is making no difference... then check for spark on the bad cyl.. and go from there.

Russ from MN · Jul 4, 2016

Sounds like it's only running on one cylinder! Make sure both exhaust pipes are hot, would be handy to have an IR gun. It might be an intermittent problem, so there might not be a big difference in temperature.

Russ from MN · Jul 4, 2016

Forgot to say we have had a couple of lawnmowers with 15 hp Kawasaki V-twins and they ran flawless for years.

Back Forty Bob. · Jul 4, 2016

If fuel line is failing you may have junk in the fuel bowl.
Drop bowl inspect / clean, if very bad you may need to tear down/
rebuild carb. Install new fuel line with a good inline filter.

steve terplak · Jul 4, 2016

Would I hear a huge difference when only on one cyl?

Would the valve issue show up and disappear so consistently or does that aspect sound more like the ignition coil?

Thanks

JD Seller · Jul 4, 2016

Bad coil or spark plug making it run on one cylinder. You can not hear the difference but your will notice the lack of power. The fuel your smelling is unburnt fuel from the one cylinder not firing. This is a common thing to happen. I would start with new spark plugs. Running the mower at less than full speed will foul the left spark plug on some models of the Kawasaki motors. They are tuned to run at rated HIGH idle and less than that makes the left cylinder run rich and will foul the spark plug on that side.

Had this issue real bad on the JD LX188 mower with older owners that refused to run them wide open while mowing. Their running the mower at 1/2 to 3/4 throttle was actually harder on the engine than running it wide open.

GordoSD · Jul 4, 2016

Fuel line has hole, fuel line is cracked. Why would you spend $2 for new line to replace that old mess? Why ask if it needs replacing?
Try using only non ethanol fuel also.

Steve in VA · Jul 5, 2016

Given a bad coil, disconnecting the faulty plug will yield no change in the engine operation. Otherwise, if you disconnect the good cylinder the engine will die immediately.

Steve in VA · Jul 5, 2016

You probably would hear only that the engine appeared to bog and not achieve full revs once the coil fails during operation. My experience was that the neighbor was convinced his problem was fuel related so he switched to non-ethanol fuel, drained and flushed the tank. replaced multiple fuel filters, replaced fuel line, spark plugs, and replaced the carb. He took the mower to the dealer but no resolution there likely because it was intermittent. Final verdict was that once I caught it misbehaving I could check the firing. Pretty much air, fuel, or fire ya know?

jeffcat · Jul 5, 2016

Had the same with a neighbors twin Briggs. It had fuel problems because the NIKI carb had a plugged jet on one side. You are a bit different. I LOVE NGK sparkplugs. Most of these engines take BPR6ES plugs. Copper core and the engines love them. Also I run only Hi-Test gas. One of my tractors goes crazy if you put regular in it. Lastly..... You can pull off one wire while the engine is running and see if it dies. Try both sides and I would bet bad plug first and then bad coil after that.

JK-NY · Jul 5, 2016

Not sure if this is your issue but- if you have a rubber gas line and it looks very cracked/(dry rotted) as you stated yours is the line may not leak fuel but it also may be cracked enough to not let the feul pump pull the fuel through . I have had this happen a couple times on different small engines. I would replace the fuel line and plugs clean the air cleaner and see where you stand.

Mashbox · Jul 6, 2016

Look at your spark plugs. My zero turn was doing something similar this spring. I would mow for a while and the mower would start to die as if it was running out of fuel. I replaced the fuel line and decided to replace the spark plugs also. One changed fine. Could not get the socket on the other plug. Found a dead mouse around the plug. Finally got the mouse out and when I pulled the plug the side had a large scorch mark where it had shorted. pulled the housing off and found where the mouse had bit into the plug wire. Looked like while mowing the mouse would move enough to ground the plug.

BarnyardEngineering · Jul 6, 2016

Easy enough to check.

Next time it's acting up, flip up the hood and pop one of the plug wires off. If doesn't change how it sounds, you found the non-firing cylinder. If it quits running, the other cylinder is not firing.

They do sound very smooth even running on one cylinder.

RustyS · Jul 6, 2016

Comparing the time it takes to drive to town verses the cost of spark plugs, fuel hose and inline filter; I would replace plugs ,hose and inline filter( assuming that hasn't been done in the last twelve months). Clean and soak the air filter and begin trouble shooting from there.

showcrop · Jul 6, 2016

The 23HP Kawi on my Ferris ZT was doing the same thing. It was coil.

Don-Wi · Jul 6, 2016

A couple things that have happened to me with a Deere with a Kawasaki v twin, was an ignition module, and vapor locking when the radiator got clogged up with dust & grass clippings.

Donovan from Wisconsin

Back Forty Bob. · Jul 6, 2016

How did the engine problem turn out?
Just curious how far off I was.

W_B · Jul 7, 2016

(quoted from post at 02:30:46 07/05/16) Neighbor's JD had similar symptoms. I was finally able to diagnosis it as a faulty ignition coil on one of the 2 cylinders. Not familiar with the cub but parts shows separate coil of each of the plugs. If you can catch it acting up, try disconnecting a plug wire.

This! Had the same issue with two of my mowers, mice had gotten in and chewed the wire from the coil causing intermittent rough running and a gas smell.

Lawn Mower Underpowered Fuel Issue?

Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Member

Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Member

Well-known Member

Member

Well-known Member

Well-known Member

Member

Well-known Member

Similar threads