B7800 - intermittent power loss/low idle to stop

   / B7800 - intermittent power loss/low idle to stop #1  

Sniggle

Silver Member
Joined
Jan 27, 2008
Messages
211
Location
Jefferson County, WV
Tractor
2003 Kubota B7800 (new to me @ 435 hours
I have had this happen a few times, to include about 1 hour ago. I was back blading the riding ring, and about 1 hour into the job the tractors idle dropped to almost nothing, it sputtered for a bit, and then died. I tried to restart a few times, and it would not get going. I checked all the fluids - good, air filter - good, fuel level - good, fuel filter - good, radiator - could not hear any boiling or see any overflow. After about 10 minutes, I decided to try her again, and she started up fine, finished the back blading, and running the rake over the riding arena...about another 45 minutes of work.

I, at present, do not have any of the gauges or lights working (except the tac), thanks to a mouse this winter. Fuel is new, fuel filter is from last year.

Any ideas on what is going on? Thanks!
 
   / B7800 - intermittent power loss/low idle to stop #2  

Cabin Dweller

New Member
Joined
Dec 13, 2017
Messages
67
Location
Grass Valley, CA
Tractor
Kubota B7800
Maybe the mouse nibbling affected wiring assiciated with the seat safety switch circuit and you're experiencing a resulting intermittent issue?
 
   / B7800 - intermittent power loss/low idle to stop #3  

orezok

Elite Member
Joined
Jan 30, 2004
Messages
2,783
Location
Mojave Desert, CA
Tractor
Kubota B7800
Loosen the fuel cap an see if that cures it. The vent might be blocked.
 
   / B7800 - intermittent power loss/low idle to stop #4  

seville009

Platinum Member
Joined
Oct 22, 2007
Messages
900
I'm no expert, but it kind of sounds like it slowly was losing its fuel source.

if loosening the fuel cap as suggested above doesn't do anything the next time it starts sputtering, I'd put in a new fuel filter, even if the old one visibly looks good. Nothing really to lose with a new filter anyway.
 
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   / B7800 - intermittent power loss/low idle to stop #5  

RjCorazza

Veteran Member
Joined
Apr 6, 2000
Messages
1,828
Location
Maryland
Tractor
Kubota L4060 Cab, ZD1211, ZD326
Other things to check / do are :
Confirm that the lift pump is working.
Blow low pressure compressed air back through the fuel lines to the tank.
Confirm the the tank and separator are not contaminated with water.
 
   / B7800 - intermittent power loss/low idle to stop #6  

Henro

Super Member
Joined
Jul 4, 2003
Messages
5,935
Location
Few miles north of Pgh, PA
Tractor
Kubota B2910, BX2200, KX41-2V mini EX
I'm no expert, but it kind of sounds like it slowly was losing its fuel source.

if loosening the fuel cap as suggested above doesn't do anything the next time it starts sputtering, I'd put in a new fuel filter, even if the old one visibly looks good. Nothing really to lose with a new filter anyway.

I was going to ask how the OP determined his fuel filter was good.

Years ago I had a different, but similar, issue on my B2910, which is the same tractor as the B7800 with some deluxe features.Turned out it was caused by the fuel filter.

Changing the fuel filter is a good idea, unless perhaps if physical fuel flow has been verified through the filter. I would change the filter anyway. Not very expensive and easy to do.

edit: Pretty sure there is no lift pump on my B2910, so probably none on the B7800 either. Don’t see one on the electrical diagram for the B2910.
 
   / B7800 - intermittent power loss/low idle to stop
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#7  
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Sniggle

Silver Member
Joined
Jan 27, 2008
Messages
211
Location
Jefferson County, WV
Tractor
2003 Kubota B7800 (new to me @ 435 hours
Thanks for the suggestions. I will swap out the fuel filter, and loosen the fuel cap if and when it next decides to sputter.

I did start it up today without a hitch to throw the belly mower on her. I do need to make time to dig into the instrument cluster and figure out what the mice damaged/destroyed. I did a look around when I removed the mouse nest, and I did not see any wires chewed, but the mouse piss had badly corroded the leads to the box that controls the instrument cluster. I am hoping I can clean it up and get back my gauges and idiot lights.
 
   / B7800 - intermittent power loss/low idle to stop #8  

Ed ke6bnl

New member
Joined
May 5, 2007
Messages
20
I am new with my b7800, but I would start with tank drain valve. Any water in fuel, if you remove hose from filter take a sample in clear container.
 
   / B7800 - intermittent power loss/low idle to stop #9  

Ed ke6bnl

New member
Joined
May 5, 2007
Messages
20
I was working on my b7800 and found a coiled tube in the engine compartment that attaches to the firewall Tha looks like the breather for the gas tank
 
   / B7800 - intermittent power loss/low idle to stop #10  

RjCorazza

Veteran Member
Joined
Apr 6, 2000
Messages
1,828
Location
Maryland
Tractor
Kubota L4060 Cab, ZD1211, ZD326
I was going to ask how the OP determined his fuel filter was good.

Years ago I had a different, but similar, issue on my B2910, which is the same tractor as the B7800 with some deluxe features.Turned out it was caused by the fuel filter.

Changing the fuel filter is a good idea, unless perhaps if physical fuel flow has been verified through the filter. I would change the filter anyway. Not very expensive and easy to do.

edit: Pretty sure there is no lift pump on my B2910, so probably none on the B7800 either. Don’t see one on the electrical diagram for the B2910.

I believe the older B Series machines have a mechanical lift pump. Unlikely to be the problem though.
 
 
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