Mower dies after running for 20-30 minutes

Bought a new fuel pump today. Installed it, cranked it without starting fluid finally. Thought I had it fixed. Ran like a champ for an hour. Stopped for supper. Went back out and cut for 45 more minutes without any issues. Then I’m a couple loops from done when I thought I heard it miss a little. Then again. I switch tanks and it stays running, other than a bit of stumbling as it switched over. But it then it really starts to stumble and I have to choke it to get back to the shop. Barely made it, but it didn’t quite die. Just hitting enough to stay running, but not enough to bring the deck on or go up a hill. If I took the choke off, i had to immediately pull it back on the keep it running. So it’s definitely fuel related, and changing the fuel pump made a big difference, but didn’t fully solve the problem.
 
not sure if this has been asked, did you go through the carb? maybe time for a rebuild or a new one?
 
I don't recall if it's been covered, or if another action you've taken can negate this, but have you checked inside your rubber fuel lines for a torn flap of rubber, or some sort of debris? Had a buddy chase a fuel delivery problem and it ended up being that one of the times that he crammed the rubber line back onto a hard line, the hard line cut a small flap of rubber that would act like a baffle and cut off fuel flow. pull the rubber line off and look in, and you wouldn't notice it. he just happened to inspect very closely and found it.

It's clearly a fuel delivery issue and it's erratic. It really sounds to me like there's some sort of debris, or something loose or something to that effect that is making it inconsistent.
 
mbalbritton said:
I don't recall if it's been covered, or if another action you've taken can negate this, but have you checked inside your rubber fuel lines for a torn flap of rubber, or some sort of debris? Had a buddy chase a fuel delivery problem and it ended up being that one of the times that he crammed the rubber line back onto a hard line, the hard line cut a small flap of rubber that would act like a baffle and cut off fuel flow. pull the rubber line off and look in, and you wouldn't notice it. he just happened to inspect very closely and found it.

It's clearly a fuel delivery issue and it's erratic. It really sounds to me like there's some sort of debris, or something loose or something to that effect that is making it inconsistent.
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Agree with this but if you go to the trouble of looking at them just replace.
 
Jeff B said:
not sure if this has been asked, did you go through the carb? maybe time for a rebuild or a new one?
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mbalbritton said:
I don't recall if it's been covered, or if another action you've taken can negate this, but have you checked inside your rubber fuel lines for a torn flap of rubber, or some sort of debris? Had a buddy chase a fuel delivery problem and it ended up being that one of the times that he crammed the rubber line back onto a hard line, the hard line cut a small flap of rubber that would act like a baffle and cut off fuel flow. pull the rubber line off and look in, and you wouldn't notice it. he just happened to inspect very closely and found it.

It's clearly a fuel delivery issue and it's erratic. It really sounds to me like there's some sort of debris, or something loose or something to that effect that is making it inconsistent.
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R Q said:
Agree with this but if you go to the trouble of looking at them just replace.
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Carb is 100% cleaned (and was clean as a whistle when I took it off), all fuel and vacuum lines are replaced also, with 300psi fuel injection style line. I replaced the pulse line with that line also, so that's the only other culprit, but I would think it would have caused an issue sooner than later instead of no issue after the first hour.
 
You may have said this before, but have you tried taking the fuel cap off when it starts running poorly?
 
VortecJeep said:
You may have said this before, but have you tried taking the fuel cap off when it starts running poorly?
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Yes. And for good measure tried it when it was stumbling yesterday too. Yesterday was the first time it kept running long enough to trial and error a few things, such as switching tanks and bustin caps.
 
R Q said:
Have you pulled the valve covers and looked to see if the push rods are straight and moving correctly? What engine oil are you using?
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I’m not sure if this is a joke or not…
I’ve set the valves, rods all looked fine, and it’s using whatever oil I put in it last year when I changed it.
 
jeepinmatt said:
I’m not sure if this is a joke or not…
I’ve set the valves, rods all looked fine, and it’s using whatever oil I put in it last year when I changed it.
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No not a joke. You should only use Kawasaki oil. It's high zinc and is best for them. I've learned the hard way. Kawasaki is calling for 20W50. Too much friction in the valve train can make them miss and stumble and eventually cause damage. Yes, your situation sounds like fuel related but I've had the stumble and power loss and it turned out to be the push rods bent from not oiling properly.
 
R Q said:
No not a joke. You should only use Kawasaki oil. It's high zinc and is best for them. I've learned the hard way. Kawasaki is calling for 20W50. Too much friction in the valve train can make them miss and stumble and eventually cause damage. Yes, your situation sounds like fuel related but I've had the stumble and power loss and it turned out to be the push rods bent from not oiling properly.
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Gotcha. I’m sure it was 20w50 but I honestly don’t remember what brand. I used a Kawi filter, and I think I got everything from the Ferris dealer, so there’s a chance it’s Kawi oil. If not, it’s probably Valvoline VR1 Motorcyle oil.
 
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