Air getting in fuel lines and IDK how?? 3325

[bbse]

I have been fighting with this 3325 for a while. It was missing, sputtering and blowing white smoke at times.....but then it would clear up and run fine. I noticed it seemed to do it more when I was on hills so I thought maybe trash in the fuel tank and/or water. I had added Diesel Service and some Heat to the fuel. I tried fresh fuel and no difference. I also figured out that it the lower the fuel level the worse it acted. So I started looking for air leaks. I replaced the O ring on the pump primer. I found I could hear the fuel going back into the tank when I pumped it. I also found that at medium throttle, while it was sputtering, if I worked the priming pump it would clear up and run fine. As soon as I stopped, it started blowing smoke again. So I tightened everything down...injectors, fuel filters, all the lines. Filled the tank to the top and it runs like a champ. As soon as the fuel level gets below the return line it will start acting up. I hope someone has had this experience and know how the air is getting in the system and how the return line is involved in this problem.

 

[RjCorazza]

Other things to check or do:
Cracked fuel lines will suck air, and can be deceptively difficult to see. Bend them to check for cracks, or just replace.

The lift pump could be bad. If electric, confirm it's connected to power and running. My ZD mower was sputtering on inclines and I eventually discovered the electric lift pump was bad.

Could be a clogged fuel line. Disconnect at various places to confirm fuel flow. If a reduced flow is evident, try blowing compressed air through the line back to the tank. Remove lines as necessary.

There are the obvious things like replacing fuel filters and confirming any shut-off valves are fully open. I'm guessing you've done that.
Good luck!

 

[thepumpguysc]

How does the fuel COME OUT OF the tank.??
If it’s from the top, that means there’s a “pick-up tube” that it’s pulled thru..
The problem sounds like a cracked p-u tube to me...
Or a weak supply/lift pump..

 

[bbse]

Thanks for the replies. I have replaced the filters, drained the tank, cleaned the shut off valves, replaced O rings, replaced fuel. I think I have eliminated those possibilities. The fuel is gravity fed from the bottom of the tank. It is right in front of the steering wheel so is higher than the filters and the injector pump. There is no pick up pump or tube. The return line to the tank is at the top of the tank. When I work the primer pump you can hear the fuel shooting back into the tank. That is the baffling part. When the tank is full, the return line is below the fuel level. Tractor runs fine...when it is below the return line it is getting air. But all the pressure in the system is on the other side of the pump. And I can find no fuel leaks. Also, when I work the primer pump it makes the engine smooth out. ??? Pressure or air?? I was just hoping someone had seen the problem before on these 25 series tractors. 3325 - 3525 - 4025 - 4500 - 5500

 

[Harry in Ky]

Look at your fuel lines. Mahindra tractors of that vintage used lines that had steel on both ends with banjo fittings. The center portion was hose with steel mesh around it and crimp sleeves connecting the hose to the steel. When I find air ingestion problems with those lines I cut the sleeves, remove the hoses and replace them with good quality rubber fuel hose and #4 hose clamps. That will eliminate the lines as being part (or all) of the problem.

 

[thepumpguysc]

That’s a thought..^
Could b the supply pump..
Unhook it at the pump inlet and turn the key.. have a bucket ready.. let it run, there should be about 10psi at the pump inlet..(6-10psi)

 

[bbse]

That’s a thought..^
Could b the supply pump..
Unhook it at the pump inlet and turn the key.. have a bucket ready.. let it run, there should be about 10psi at the pump inlet..(6-10psi)

It doesn't have a pump....it is gravity fed

 

[bbse]

Look at your fuel lines. Mahindra tractors of that vintage used lines that had steel on both ends with banjo fittings. The center portion was hose with steel mesh around it and crimp sleeves connecting the hose to the steel. When I find air ingestion problems with those lines I cut the sleeves, remove the hoses and replace them with good quality rubber fuel hose and #4 hose clamps. That will eliminate the lines as being part (or all) of the problem.

Thanks...that is worth a try. Probably needs it anyways.

 

[EddieWalker]

Try swapping your intake and return line going into your tank. On my New Holland, the intake is lower in the tank and prone to pick up something. This can be a real problem if you have a metal tank. When the fuel level is low, the metal rusts on the inside of the tank, then it flakes off into the tank.