Cub Cadet 7260 ran out of diesel, and now it won't stay running.

[gmiles123]

I'm new to the TBN forums, so I apologize in advance if this is a stupid question

I recently purchased a Cub Cadet 7260 that has a 3-cyl Mitsu diesel engine. I've worked on gas vehicles for the past 16 years, but I'm new to the diesel world.

Like a rookie, I ran the tractor out of fuel because the fuel gauge isn't currently working. At the time, I didn't know about bleeding the air out of the fuel lines. I filled the fuel tank and tried to start it a few times, of course with no luck. That's when I learned I needed to bleed the air. I followed the process in the owner's manual for bleeding the fuel lines. This time the tractor started up, but was running rougher than before, with little to no throttle response, and it eventually died. I thought maybe there was still air trapped in the lines between the injector pump and the injectors, so I seperately cracked each line at the injectors while cranking the engine. I started the tractor again with a little improvement, but it eventually died. I repeated this process several times with no more improvement.

On the last time, I decided to try individually cracking the lines while the tractor was still running. When cracking fuel line closest to the firewall, and the center fuel line, the engine died immediately. When cracking the fuel line closest to the radiator, the tractor started running great. Throttle response was back, and it was running the way it did before running out of fuel. I let the tractor run like that for a few minutes, thinking it was working out any remaining air. The only problem is that when I tightened the fuel line back onto the injector, it starts running rough again, and eventually dies. I repeated this process a couple of times with the same result.

Any ideas on what this could be? Or what I should try next?

Thanks!

 

[deezler]

Geez, sorry for your troubles.

I'm not sure we have the same engine, as mine is the 30 BHP model which I believe moves to the direct injection setup. But I have run mine out of fuel a few times also, from clogged fuel filters. I always just change the fuel filter, fill up the filter housing with fresh diesel, and start 'er up. Usually after a few seconds of running it stumbles and blows smoke for another 10-20 seconds before clearing up and running good as new. I felt lucky to never have had to bleed the system.

So your engine ran great before you ran it out of fuel? Thats really odd that it would run great with cyl 1 fuel line loosened, but run crappy again once it's tightened down. Is this experiment repeatable? if so, it seems to imply that there's a problem with this injector.... no?

How many hours on this beast?

 

[gmiles123]

Thanks for the response!

Yes. It ran great before I ran it out of fuel. The tractor has 1190 hrs and has 26 bhp, so I don't think it's the same one. The experiment is repeatable. I can loosen the fuel line, start it up, and it runs great. I had the same thought about the injector, but I don't know why it would run better with the fuel line cracked. Again, I don't know that much about diesels, but it seems like if the injector had a problem then it would run poorly no matter what. I guess my next step would be to remove the injector from cyl 1, and take it to get tested.

 

[deezler]

By the way, you may want to re-post this in the general operating section, it would get more response.

Yeah, it doesn't really make sense that if one line was cracked loose, that the engine would run smoothly. it should have a noticeable stumble without one cylinder firing accurately.

When you crack the lines loose (while it's running), do they leak a continuous stream of diesel fuel?

My initial thought had been, that if the front cylinder's injector had clogged or failed, that it may strain the pump when the fuel line was tight, reducing pump performance, thereby affecting the other cylinders, and when loose, allowed the other cylinders to run better. But I'm not sure I buy this, thinking about it again.

Hard problem to diagnose over the internet. You could try a quick youtube video while you crack and re-tighten that fuel line with the engine running. And then post in the bigger forum section.

Or hopefully, you will just reply now that you solved it, haha.

 

[George2615]

I think the 7260 is the same as the Mahindra 2615 3 cyl Mitsubishi 26 HP. I used to have one. You shouldn't need to run the motor to bleed air. Just turning the key on starts the fuel pump which you should hear it ticking away. Start at the filter and bleed the air there, then move to the injectors one at a time. That is strange that it will run smooth with the front line cracked for bleeding. May be an injector problem but unsure why it would run smooth with the line cracked loose. Perhaps if the front injector is plugged cracking the line loose relieves the pressure. When you tighten it back up and if that injector is plugged the excess fuel is probably going to the other two cylinders giving them too much fuel causing it to stumble and die (actually flood out) those cylinders. Just a possibility.

 

[George2615]

Another member just had a similar problem on his machine with only 64 hrs. Turns out when he ran out of fuel there must have been some rust in the tank that got into the filter. How many hours are on your filter. On my Mahindra 2615 I used to replace the filter once a year whether it needed it or not. Have you found the problem yet?

 

[gmiles123]

Thanks for all the responses!

I was out of town this past weekend, so I didn't get to mess with it as much as I wanted to. It is extremely possible that the fuel filter, injector, or both are clogged from rust or something from the tank. I bought this tractor from a guy who got it at auction, so who knows the last time the filter was changed. I just received my new fuel filter assembly at the end of last week (which I had already ordered before this) so I'll put that on and see if there is any change.

The other theory I have is that air is somehow being introduced somewhere in the system, either at the filter assembly, lines, or fuel pump. After the tractor dies, I can repeat the bleeding process and remove air at the injector pump bleed screw. Also, when cyl 1 injector line is cracked, it produces a fairly steady stream of tiny bubbles, similar to what you see when testing a tire for a leak with soap. Has anyone heard of air being introduced into the fuel system somehow? After I replace the fuel filter assembly, I plan on disconnecting the fuel line from the injector pump, putting that end in a jar, turning on the fuel pump, and watching for bubbles.

If that's not it, then I guess it's time to pull the injector.

 

[ncmower]

I have the same problem with a 7223 3 cylinder. I seem to be getting air in the system. I have replace the fuel filter assembly, the fuel line, the fuel pump and still seem to getting air. The tractor will run fine for approximately 15 minutes and then start missing and finally stop.

 

[scoutcub]

I would tend to agree with the clogged injector theory. Probably picked up some dirt or rust at the bottom of the fuel tank.

Some diesel powerservice wouldn't hurt......and replace/fix that fuel gauge!!