Fuel issues with 33r877

[Steve-p]

I have a JD d110 with a 33r877 that has been sitting for several years. Replaced the battery, cleaned the carb and put in fresh gas and now it will crank right up.

It runs for a few minutes the starts surging getting worse and worse until it dies. The fuel filter looked pretty bad so I replaced that and the fuel pump and no change.

Here is the part I can’t figure out- after replacing the pump I figured out that if I disconnect the pulse line from the pump it will run like a champ for a minute or so until it runs out of gas in the carb. It goes back to surging immediately when I reconnect the pulse line.

I can’t find any clogs or blockages in any of the lines so I have three thoughts
1- vacuum leak somewhere
2- something floating in the tank clogging the pickup while the engine is running then floating back to the bottom
3- something going on in the crankcase

Any ideas on this one? My next step as far as I can tell is pulling the tank which seems like a pain in the neck, or rigging up a gravity feed fuel tank on the hood and bypassing the pump.

Thanks for reading through all that and I would be grateful for any suggestions

 

[Tinkerer200]

I always have a test gravity feed gas tank at hand and I think you are on the right track using one. Problem not in crankcase. Suspect leak in vacuum line or pump diaphragm. Your test tank will help tell you.
Walt Conner

 

[bertsmobile1]

And just to be different , I see a lot of fuel tanks blocked by floating debris that floats away when the engine is turned off .
And yes like Walt, I like to do substitutions like using an alternative tank to isolate where a problem is