(Help!) My B7800 has begun shutting itself down

My B7800 has begun shutting itself down – and it is NOT a faulty seat switch. I’ll be running it for a while – maybe as much as an hour – possibly only 30 minutes (I have yet to actually time ‘it’). This happened the last two times I’ve had it ‘out’ and working.
The engine seems to stall, slowing to an anemic idle - and it is not responsive to the RPM handle – will not increase RPMs when moved appropriately.
I recall turning the engine off and starting it up again the first time this happened but the ‘condition’ remained and I could not move the tractor or the FEL or the Box Blade.
So, I gave up and went off to have a coffee and call the dealer. They were closed. So, I drank my coffee and thought about the problem figuring to call the dealer again come Monday.
Then decided to walk to the field and try starting it up one more time to see if I could drive it back up to the shed to get it under cover.
Started right up and carried me to the shed where I put it away to rest.
Some weeks pass, a dealer tells me I should check the fuel filter as it appears to him that I may be sucking some stuff into the filter which, over an hour or so dislodges and allows the oil to get to the engine normally.
Now, I looked at the filter and did not see any indication of a ‘lot of crap’ beneath the filter. Indeed, it looked pretty clean. Remember, I am not a farmer and do not run this tractor much at all. Bush Hog a couple acres every year (not this year), scrape the driveway after too much rain and (occasionally) move heavy stuff about with homemade forks on the FEL. If I run it 25 hours annually, I’d be surprised.
So, I started it up the other day to dig a bit of a trench using one long ‘tooth’ hanging down the one side of the box blade. After about 30 minutes or so, it started dying out and I left it for a few hours before starting it back up and putting it back under cover.
I did check the fluid level by pulling the yellow ‘plug’ thing on the ‘floor’ by the seat and it looked as if there was no fluid on the stick. So, I priced Super UDT and looked for less expensive alternatives which is how I happened upon OTT and joined so I might post this situation and get some advice.
Now, it could be the fuel filter. I know I changed it (and the other liquid filters) three years or so back and it does appear rather clean. Also, I’m not sure how much of the half-full tank will leak out if I simply unscrew the filter bowl to look more closely at the filter and any contents/residue that might be in there.
Hope this proves sufficiently detailed!
By the way, I was much impressed by the faulty seat (dead man) switch diagnoses for Diane (which I came across searching for help with this issue).

Thank you all.

OK, some suggestions t check out. I had been hesitant about unscrewing the fuel filter bowl for fear all the fuel in the tank would rush out. I appears there is a mechanism that prevents that (read in another post after searching for Alge!).

I will look to the fuel filter and lines and see what I can - I do not have a manual or repair guide so I go slower than I might! Will report what I find.

Thanks again for your help.

"a little check valve"

I found it - after a while.

For reasons I do not unnerstan, once I removed the bowl and filter, fuel ran consistently from inside the top of the fuel filter.

I pinched off the left tube (it seemed most likely to be connected to the fuel tank) but that did not stop the flow. I pinched off the smaller tub entering at the top of the filter (it is connected to the upper front of the fuel tank) and that stopped the flow!

Then, reaching under the fuel filter housing and pressing up on the check valve, I could start the flow from the bottom of the fuel tank (the hose on the left).

Of course, if I unpinch that smaller tube, fuel flows again.

However, I still have no idea why the fuel was leaking from that (top) tube (nor why the check valve didn't 'check' its flow) so I may be no closer to a solution as I wait a new filter from Amazon (dealer wanted $18 plus another $3 for the two o-rings) at $9 for filter and o-rings set to arrive in four or five days. I'm in no hurry. Also ordered another complete set of filters while I was at it and some Algae Killer.

The filter was very dirty and there were a few bits of reddish brown (I think 'glop' is the word) material evident in/on the filter and fuel inlet area.

The small tube from the tank to the top center nipple on the fuel filter appears to return to the fuel line after the pump as if it is some sort of a 'return' channel for excess fuel pumped to the injectors, but not used/burned/consumed.

Dealer's Parts Guy did not seem aware of the tube and had to look it up to show me where it (and the other tubes) connected before/after the filter housing.

Looks as If I'll simply do an R&R on the fuel filter and cross four fingers.

Also bought some Super UDT $65/2.5G to top off that system after I swap out the filters.

QUESTION: If i unscrew the filter, will it drain the UDT in the system as it would in a car or will I simply lose a quart or so (whatever the filter holds)?

I realize one normally drains the fluid, then removes the old filter.

But, since I want to retain the S UDT I have and simply replace the filters . . . should I buy another 5 gallons of S UDT because what I want to do can' be done?

Anyone know for certain?

"you have pressure in the tank (blocked vent)"

I have removed the Tank Filler Cap - so how is there "pressure" (other than atmospheric, of course) in the tank?

One thing I noticed was that the 'innards*' of that cap are not secure and have fallen out a couple of times during this filter change effort when I remove the cap to look, add additive, stir the fuel, etc.). Since I never knew they were there and have no memory nor diagram of how they were installed - I am not sure how to put them back again. Anyone know?

As to the 'pressure' issue, it remains a mystery. I've not run the tractor for days. As I recounted, the check valve' in the filter housing is working and holds back the fuel that might otherwise flow from the tank side tube at left. I suspect I need get a suitable container and collect what fuel may flow out of that small tube and hope it stops flowing soon - as the tank is 3/4 full (I was not planning to replace the fuel filter it was in response to a failure to operate). Hence the tank was not even close to empty when I tried replacing the fuel filter.

The last time I changed this filter, the valve in the filter housing assembly prevented any excessive fuel spill and nothing so much as dripped from that top bit!

If anyone knows why that fuel is flowing and what I should do to fix it . . . It might just be that it was not a dirty filter but whatever's causing that fuel o back up into the filter housing that was the cause of the original issue??

* 2Pcs - A flexible black piece and a white plastic washer-like piece.

OK, the new fuel filter and gaskets arrived and was installed. Also had added anti-Algae chemical as suggested.

This did NOT solve the problem. Ran for 15 min or so, and then slowed down and died. Waited 20 minutes or so and started it up and drove it up the hill and into the barn.

Anybody have any other suggestions before I call a dealer to deal with the problem?

"...a restriction in the fuel line..."

When I installed the new fuel filter, fuel poured out as soon as I hit that little valve up inside the fuel filter assembly.

As well, fuel ran out of the filter assembly unless I clamped the small center hose coming in from the side (upper, front) of the fuel tank. It would appear that there is no restriction - but I will try running it again to see if I can stall it again to check the fuel in the fuel filter bowl and report back.

The Gas and Temp Gauges are not working either, so I need to check fuses?

I'll check for fuel leaks. However, there was no evidence of fuel on or round the 'dusty' lines when I looked earlier. Will look again.

UPDATE: Just paid close to Seven Hundred Dollars to a Kubota Dealer to replace the fuel pump! Sixty Dollars in transport fees and 4.5 Hours of Labor at $89/hr!

The mechanic said "You had gas in your fuel tank and it destroyed the fuel pump.

Makes NO SENSE to me - if the pump did not work, how was I able to start the tractor and run it for twenty minutes before it died. Then after waiting twenty minutes, start it up and put it away?

I cannot take this old pump apart to see if the diaphragm's busted - so is there another way to test it?

boz1989 said:

Did they replace the fuel pump, or the injector pump?

Click to expand...

They replaced the mechanical fuel pump and gasket. I have the part they claim was my old one.

They claim the diaphragm (in the pump) has a leak in it because there was gasoline in with the diesel fuel.

They charge $89/hour for 4.5 hours of labor.