B7610 losing power and dying

[truksmith]

Howdy:

New to the forum but been following for a while. Not too savvy with a wrench but learning as I go with this toy, and I could use some expertise here: Got a B7610 with about 400h 2 years ago and it's been working great for me. Recently damaged the radiator and fan, which I replaced, and it had been running fine until a week ago I noticed that while mowing it would occasionally randomly lose power (RPMs would drop to about 1000) for a few seconds, then resume full throttle. It would happen every 5 or 10 minutes or so, but couldn't find a rhyme or reason to what I was doing when it happened. Chalked it up to maybe something in the fuel line. Then last week I mowed for about an hour with no problem, until it started dropping RPMs more frequently. RPMs would rapidly go down, and sometimes it would recover, but then began stopping altogether. When it would die, I could restart it with prolonged turning over and it might run for a minute or so, so with multiple cuts and restarts I got it to the garage. Getting it home with multiple restarts depleted the battery so I left it for today.

Today I recharged the battery, drained the entire fuel tank (wife had bought the diesel that I had been using for the last week), cleaned out the fuel filter and refilled with new diesel from a different station. Thought maybe there was air or water in the fuel lines so I bled them and she started right up, no problem, no sputtering. Patting myself on the back and blaming the bad fuel on the wife, I went out and mowed for about a half hour without any problems, and then it lost RPMs and died again, not wanting to restart (would turn over and sputter, but would only run at low RPMs and then die). Realizing that I must've been off about the bad fuel/water/air in the lines, I decided to just leave it in the field for a while to let it cool off, and when I went back a half hour later it started up with effort and ran fine for the 5 minutes I took to finish where I was at and get it back to the garage.

So it seems to run fine when cool but whereas it was previously just losing power temporarily, it's now dying after about a half hour of running fine. All fluids look good and it's not overheating on the gauge. Does this sound like an obvious fix to anyone out there?

Appreciate any help!

 

[85Hokie]

Howdy:

New to the forum but been following for a while. Not too savvy with a wrench but learning as I go with this toy, and I could use some expertise here: Got a B7610 with about 400h 2 years ago and it's been working great for me. Recently damaged the radiator and fan, which I replaced, and it had been running fine until a week ago I noticed that while mowing it would occasionally randomly lose power (RPMs would drop to about 1000) for a few seconds, then resume full throttle. It would happen every 5 or 10 minutes or so, but couldn't find a rhyme or reason to what I was doing when it happened. Chalked it up to maybe something in the fuel line. Then last week I mowed for about an hour with no problem, until it started dropping RPMs more frequently. RPMs would rapidly go down, and sometimes it would recover, but then began stopping altogether. When it would die, I could restart it with prolonged turning over and it might run for a minute or so, so with multiple cuts and restarts I got it to the garage. Getting it home with multiple restarts depleted the battery so I left it for today.

Today I recharged the battery, drained the entire fuel tank (wife had bought the diesel that I had been using for the last week), cleaned out the fuel filter and refilled with new diesel from a different station. Thought maybe there was air or water in the fuel lines so I bled them and she started right up, no problem, no sputtering. Patting myself on the back and blaming the bad fuel on the wife, I went out and mowed for about a half hour without any problems, and then it lost RPMs and died again, not wanting to restart (would turn over and sputter, but would only run at low RPMs and then die). Realizing that I must've been off about the bad fuel/water/air in the lines, I decided to just leave it in the field for a while to let it cool off, and when I went back a half hour later it started up with effort and ran fine for the 5 minutes I took to finish where I was at and get it back to the garage.

So it seems to run fine when cool but whereas it was previously just losing power temporarily, it's now dying after about a half hour of running fine. All fluids look good and it's not overheating on the gauge. Does this sound like an obvious fix to anyone out there?

Appreciate any help!

well you hit all the good spots- i would have said all the things you did !
I would say you have a weak spark....ok kidding !!!! I wonder if something in the fuel pump is somehow getting hot and quitting , but that doenst make sense either. Have you tried to run it with the fuel cap off???? try that and see if it makes a difference, if tank is full - unscrew enough to let air in - see if that makes ANY difference.

 

[kc8fbl]

I'm wondering if it is a faulty fuel stop solenoid? I've heard those can act up when operating temps are achieved. Definitely try unscrewing the fuel cap when it starts to sputter and see if that helps. Check your fuel filter again. Check any rubber lines and see if there is any cracks in them. Fuel return lines from the injectors can be cracked and leaking?

Also, maybe try some seafoam in the fuel. It will help to get rid of any water that may be in the fuel. Try these things and report back. Hopefully, it will be an easy resolution to the problem. Good luck!

 

[Tx Jim]

1st and simplest thing I'd recommend is installing a NEW not cleaned fuel filter. I presume one has a good fuel flow from tank?

 

[truksmith]

Thanks for all the thoughts:
Changed out the fuel filter and air filter today (was probably about due anyways). Neither looked horribly dirty. Flow from the tank seems to be pretty good based on the amount of diesel I'm leaking every time I take the fuel filter on/off(!), but it took a couple of hours to completely drain the (pretty much full) tank last weekend when I drained what I thought might be the bad fuel. Added Seafoam as well to the tank tonight.

Started up no problem, ran for about ten minutes, but then started cutting and dying again. Doesn't seem to make a difference if the tank is capped or not. Let it cool off for a bit and then limped back to the garage to regroup. The fuel lines look pristine--no leaking fuel, and no visible cracks--everything looks great. Starting to wonder if it isn't something faulty with the fuel pump, as it definitely seems to run fine for a while, and then just suddenly decides to lose power and die.

Any other thoughts on this one? I appreciate everyone's help!

 

[jeep08ham]

It appears you have covered most of the bases. One item I would check is the electric fuel solonoid to (1) make sure it is getting supply voltage all of the time (2) it is moving properly and not restricted. A friend of mine had a newer Kubota with a bad lift fuel pump that would not put out the correct pressure causing a similar problem.

 

[kubotasam]

Flow from the tank seems to be pretty good based on the amount of diesel I'm leaking every time I take the fuel filter on/off(!), but it took a couple of hours to completely drain the (pretty much full) tank last weekend when I drained what I thought might be the bad fuel.

How much fuel does it take too fill your tractor? I know it would not take a couple of hours to drain the tank on any tractor I have ever owned. I think you have a restriction in the outlet of the fuel tank or the fuel line leading to the filter.

 

[truksmith]

You know, it did seem kind of drawn out. It gushes now (when the tractor is working), but when I was draining it last weekend it went down to a tiny trickle. I just assumed it was getting low, but it continued for a while. It only holds 5 gallons. Would an obstruction in the outlet cause that kind of loss of power? I'm wondering if maybe a leaf or some debris got in there when I was filling it and is intermittently obstructing the outlet--that would explain the random nature of it.

I'll see if I can find some time to remove the tank and take a good look at what's inside and report back before I go testing the fuel solenoid...

 

[BAP]

If it has rubber fuel lines, it could be the insides are starting to disintegrate causing the inside to close up.

 

[jeep08ham]

Over the years I have seen many strange things floating around in a fuel tank. Leaves, grass clippings, sawdust are fairly common. The strangest thing I found in a Semi back in the early 70s with an intermittent run and shut down, was approximately 75 half pint Vodka bottles in a tank. Seems the company had problems with one of their security guards that liked to hide the bottles in the tanks. They found several trucks after that with Vodka bottles in them too.

 

[D2Cat]

Something you might try. Remove the fuel line where it attaches to the fuel filter. Remove, or loosen, the fuel cap. Blow into the line, if you use a compressor only a few pounds pressure will do.

If there is an obstruction in the tank it may clear it. Reconnect the line, bleed and see how it runs and how long. This may help you isolate the problem.

Bought a 930 Case a few years ago. Folks had been using it in the hay fields. I choked down a few time and eventually quit running. They needed to get hay wrapped so they went to a different tractor. This machine set for a couple of years. Paid $1200. Had a wad of hay crumbs at the bottom of the tank and choked off fuel supply.

I'll never forget the look on the previous owners face as we drove it off, right by his front porch! In about two hours we installed different front tires, batteries, fuel, fuel filter, aired back tire and had it fired up. All we really did was unscrew the drain valve, used bailing wire bent to hook grass and added fuel.

 

[truksmith]

Finally had the time to look into this and take off the tank--second time swishing things around a big beetle came out with the diesel...just big enough to completely obstruct the fuel line...so hopefully this is the "bug" in the system...ran it for a while afterwards with no problems, except now the gas gauge isn't reading--either I hung it up washing things out or I've got a loose wire somewhere. Gives me another project for the near future.

Thanks for all the help. Glad I got this resolved (at least I think)...