Murray 5/25

[balooba]

Hello!
I need hard core expert level help with my Murray 5/25 engine.
The engine works, pretty good, but I can't keep it running.

If I actively adjust the choke then it runs somehow, but without that adjusting the engine stops.
I have inspected the carburetor very carefully. Took it apart, replaced the gaskets, cleaned it - but obviously I have missed something.
What should I do? Any specific ideas?
Or should I try to buy a totally new carburetor, or the whole engine? Do you have one for sale?

All help, advice and ideas welcome!
A BIG thank in advance!

 

[Bertrrr]

Any time you have to engage the choke to keep it running , it's a fuel problem, start at the tank , fuel lines, filter, then fuel pump if there's one on that machine,,,,,,,then carburator. Post your results

 

[balooba]

Any time you have to engage the choke to keep it running , it's a fuel problem, start at the tank , fuel lines, filter, then fuel pump if there's one on that machine,,,,,,,then carburator. Post your results

Thank you for the advice.
Yes, it has to be a fuel problem.

I have missed something. The carburator is a ”jet pulse” type, not very complicated but the problem is a total mystery for me.

Is there some nozzle, intake or something that I should look and inspect especially carefully? Or some basic test that I could do?

Here some photos. All extra ideas are more than welcome!
If I find out the problem, I will report here!




Above: new parts.


Above: fuel tank and the carburetor.

 

[Rivets]

I’ve seen this many times and the most common cause is a warped tank, not getting a good seal between the carb and tank. Before replacing the carb try this down on the farm fix. Clean the area where the carb mounts extremely well. Install the carb, careful not to over tighten the mounting screws. Now apply a thin bead of silicone caulk around the edges of the carb, sealing any gaps. Allow to dry for an hour. If this solves the problem, you now know that the tank is bad and it’s time to start looking for a new one. The seal will last for awhile, but definitely is not a permanent fix.

 

[balooba]

I’ve seen this many times and the most common cause is a warped tank, not getting a good seal between the carb and tank. Before replacing the carb try this down on the farm fix. Clean the area where the carb mounts extremely well. Install the carb, careful not to over tighten the mounting screws. Now apply a thin bead of silicone caulk around the edges of the carb, sealing any gaps. Allow to dry for an hour. If this solves the problem, you now know that the tank is bad and it’s time to start looking for a new one. The seal will last for awhile, but definitely is not a permanent fix.

Okay, great. Thanks!
I think I've heard about that ”warped tank”...
Below some photos. Is those the surfaces (marked with red arrows) that should be well sealed?

 

[Rivets]

You don’t want sealant between the carb and the tank. Just want to make sure the edges are completely sealed. Also, a new gasket on the carb is definitely needed. I’ve even seen people double up on that gasket.

 

[Rivets]

I should have added, if you have not replaced the pump diaphragm now is the time.