Ventrac 4500Z quits unexpectedly

[Randy Miller]

I'm running a 4500Z with the Kubota engine. The machine only has 300 hours on it but I'm now having troubles with it stopping unexpectedly. Sometimes it quits after 5 minutes and sometimes it will run fine for 10-15 minutes. Seems to idle forever fine but as soon as it's under load the issue begins. Changed the plugs, air filter is clean and even added some gas line antifreeze in case of moisture. I could see some blue flame from the muffler at one point but it acts like its starving for fuel.

It will immediately re-start after stalling and might run 1 minute or 10 before stalling again.

Thoughts??

did you ever figure out what the problem was with you ventrac? I am having exact same issue

 

[sandman2234]

did you ever figure out what the problem was with you ventrac? I am having exact same issue

Have you tried the suggestions mentioned? Loosening the fuel cap is one way to see if the tank vent is clogged. Hope this helps.
David from jax

 

[Tony H]

did you ever figure out what the problem was with you ventrac? I am having exact same issue

Sandspiders love the smell of today's gasoline. They build airtight nests in venting areas
Loosen fuel cap and see if stalling issue goes away

 

[Randy Miller]

I have taken the cap lose since it doesnt have a vent on it, I am going to take the sheet metal cover off and check the actual tank vent...in my mind I am thinking if the vent was clogged how would it run for an hour and then start dying? Plus it will start right back up and idle all day. It just seems odd. I will clear vent, and pull the fuel sending unit from tank and see what it looks like. I already blew the fuel filter out and it was clean.

 

[Randy Miller]

Does it putter out or is it abrupt? I had an issue with my e-brake where it was a little loose. I would be moving and hit a bump or something and it would move and kill the engine immediately. The sensor thought that the brake was on and the tractor will not let itself move if the brake is on. I fixed it by tightening up the nut on the brake bar down by your right foot.

its not abrupt, it will start purging and then eventually die if i dont pull the choke. So I let it die and then wait like 30 seconds and it will start right back up, but can t put a load on it

 

[Tony H]

If the vent is semi clogged, it may take a long while for the pull of the carburetor to create enough vacuum that it can't draw anymore fuel. But with the semi clog, it loses some vacuum, which let's you start it again.
It will run all day at idle because at idle the vent can keep up.
Here's a whole 'nother idea. This happened to me. Had an engine that would run a while but not under load. No load it would run and run. Turned out, after going crazy, that the rubber Seat in this Briggs engine slid down on the carburator a little bit. This caused the needle to shut off fuel with very little fuel in the bowl. The heavy fuel draw, while under load, would run the bowl out of gas.
Another trouble shooting nightmare... Similar scenario. Start up mower in the morning, it would run for 3 minutes then stall out. Wait a minute, start up again, it would run for 30 seconds, like clockwork. Start again, stalls in 30 seconds. The rubber seat in that Briggs engine got deformed from way old gas working on it. The hole, in the Seat for the gas flow was distorted allowing very little gas to flow. The first startup of the day, mower had a full carburetor bowl. after that, gas dribbled in so slow, I could only get 30 seconds put of it.
Check Carburetor Seat if it's a rubber type pressed into the carburetor body

 

[Tony H]

Not familiar with the Ventrac engine.. Overhead valves? Check valve clearance. These new overhead valve engines are finicky. An hour of heat up is a long time, I admit but maybe the valves are not fully opening when very hot if valves are set too tight.
Just throwing my thoughts out to you

 

[AWSubie]

Sounds like a carburetor main jet blockage.

Remove the bowl and take a piece of fishing line or a coarse bristle from a paint brush or a thin copper strand from a length of wire and gently push it through the jet orifice.

Sometimes the jet must be removed to get to a metering tube to clean it as well.

 

[Tony H]

Just talking out loud, again. That 3 cyl Kubota engine sometimes has a propane conversion kit at the carb. Any chance some fuel shutoff solenoid for propane substitute is malfunctioning? Some broken spring or something.
We had the engines on our large scissor lift and they are great. Would love to take one off an old lift and put it in my old Cub Cadet

 

[Randy Miller]

If the vent is semi clogged, it may take a long while for the pull of the carburetor to create enough vacuum that it can't draw anymore fuel. But with the semi clog, it loses some vacuum, which let's you start it again.
It will run all day at idle because at idle the vent can keep up.
Here's a whole 'nother idea. This happened to me. Had an engine that would run a while but not under load. No load it would run and run. Turned out, after going crazy, that the rubber Seat in this Briggs engine slid down on the carburator a little bit. This caused the needle to shut off fuel with very little fuel in the bowl. The heavy fuel draw, while under load, would run the bowl out of gas.
Another trouble shooting nightmare... Similar scenario. Start up mower in the morning, it would run for 3 minutes then stall out. Wait a minute, start up again, it would run for 30 seconds, like clockwork. Start again, stalls in 30 seconds. The rubber seat in that Briggs engine got deformed from way old gas working on it. The hole, in the Seat for the gas flow was distorted allowing very little gas to flow. The first startup of the day, mower had a full carburetor bowl. after that, gas dribbled in so slow, I could only get 30 seconds put of it.
Check Carburetor Seat if it's a rubber type pressed into the carburetor body

i was able to get to the vent line and it did seem plugged, i hooked up air hose and blew it a few times and finally got it cleaned out. I cleaned air filters, radiator screen, blew out the fuel filter..it is fuel injected with electric fuel pump. We have bad weather for rest of week, my plan is saturday take out and put it to use hope it runs good.