Z122R stops running after about 1 hr

[Auto Doc's]

Hi NormanB,

That is rational. Verify the actual pump pulse vacuum line is not loose, cracked or split.

The extra fuel means more weight in the tank so the fuel will feed easier to the carburetor. When the fuel gets low, the pump has to work harder. If the vacuum pulse line is cracked or the pump is bad, the pump will not work efficiently.

These pumps are a simple crankcase diaphragm pulse pump on most models.

 

[NormanB]

Thanks for the info Doc. I'll check out the vacuum pulse line tomorrow.

 

[NormanB]

Finally found the problem. All the fuel lines are in good shape, the pump pumps, the filter is new, everything is OK. So I found a Youtuber small engine guy who was trouble shooting similar ZTRs with the same symptoms. He said the first thing he checks is the little elbow that comes out of the fuel tank. It is small and has a small ID that gets clogged easily. I didn't think that was my problem because I was able to move fuel from the tank through the filter by applying some pressure in the tank through filler cap opening with my compressor. But evidently there was a constriction in the line that didn't let enough fuel through. So took the elbow off and blew it clean just like the Youtuber did. Sure enough there was a small about of very fine debris in the little elbow; just enough to slow the fuel flow. Now the engine runs fine without stopping. Such a simple solution. Always start with the easiest fix first. Isn't that what our dad's always told us? Thanks for your suggestions Doc.

 

[Auto Doc's]

Hi Norman,

I just took care of a 4440 JD farm tractor for a simple fuel elbow issue like you described. Every time the tractor was under load baling hay it would struggle a stall down. The tank was removed and cleaned, and I had to work forward from there. It was debris that got into the tank from the fuel source or a dirty fuel can while in the field. Once I found and cleared the garbage out of the fuel elbow fitting, the tractor has been running strong.

The strangest mower fuel valve issue I had was a couple of years ago on a Cub Cadet Z-Force 48 with a 90-degree fuel valve at the top of the tank. I could mow for about 30 minutes, and then the mower would lose power. I looked over my shoulder at the cut off valve and it was moving by itself to the closed position from vibration. I blew out the lines good with shop air and replaced the valve; the customer had been running it since.

 

[Auto Doc's]

Sounds logical, but the lines a fitting all the way back to the tank need to be cleared out with high pressure air. It is amazing how many times I have found grass debris and other trash clogging up the fuel flow in lines.