Kawasaki Mule 620 starting issue

[_fudge]

Trying to help my brother with a massive headache on his 2007 Kawasaki Mule 620 4x4. It's a low hour machine, and it's suddenly giving us major problems.

It'll start and run fine for about a week after a pro shop "fixes" it, but then it bogs down, backfires like crazy, and just won't start at all. We're pretty sure it's a fuel issue.

So far, we've confirmed it has a strong spark and replaced the fuel pump and both filters.

Tried a new cheap carb, which was a disaster, so we put the original back on. It ran great for about five minutes and then the problem came right back.
The weird thing is that the fuel filter before the pump is barely getting any gas. We think there might be a blockage or something in the fuel tank itself, but we can't seem to get it clean.

My brother's next idea is to try an external, temporary fuel tank just to see if that's the real problem.
Has anyone ever run into this kind of phantom issue? Any ideas what we might be missing?

 

[Pattern-Normal232]

Looks you're on the right track with the external tank test. If fuel flow improves, that points to a clogged pickup or debris in the tank. Some resolved this by using compressed air to backflush the fuel line from the filter to the tank

 

[GetSmatrt6]

Stop chasing your tail, just run an external gravity-fed tank. If it solves the issue, your OEM tank or vent is the real culprit...too many waste time when it's just internal junk or collapse.

 

[workrigwizard163]

If you're experiencing intermittent fuel starvation, it could indicate a blockage in the tank vent or problems with the internal pickup tube. Start by conducting an external tank test, then inspect the tank vent line and the pickup screen for any debris or signs of corrosion.