B1750HST's losing power

Cyril

New member

Equipment
B1750HST
Apr 9, 2012
4
0
0
Ireland
I have a B1750HST Kubota tractor that loses power ocassionally especially when operating at full throttle. This happens regardless of PTO load and will even occur when travelling on the road just carrying a finishing mower. I have a new fuel filter & air filter installed, (they were pretty choked when I got it) and it has greatly improved the engine performance and cleared the smoke. I see from threads that the B1750's can suffer from this power loss but nobody has adviced anything other then changing filters. Is there a design limitation with fuel flow from the fuel filter to the fuel pump? Is the fuel pump cavitating or would the fuel lines have weakened and get sucked in by the pump pull as they are flexible tubing? I would really appreciate some advice on the this and I get the impression I'm not alone, with other B1750's losing power on slopes (as mine does), affecting power steering performance etc as other forum members mentioned. I would imagine these are symptoms rather then causes. My B1750HST tractor is every original and otherwise a great machine!
 

birddogger

New member
May 29, 2011
433
0
0
Pittsburgh
In humid climates the diesel fuel can grow a slime from fungus and bacteria. This slime can slowly choke off fuel delivery lines. There is also a line from the injector rail that returns to the fuel tank. Drain the tank. pull the fuel lines and check for a slimy build-up. Clean or replace the lines. Add some "Biocide" to the tank to kill it off and prevent regrowth.
Look at http://www.powerservice.com/bk/
There should be a similar product in your area.
 

hodge

Well-known member
Lifetime Member

Equipment
John Deere 790 John Deere 310 backhoe Bobcat 743
Nov 19, 2010
2,849
367
83
Love, VA
You might also want to check your vented fuel cap, or just replace it. If the tank isn't venting, then it can slow the flow of fuel.
 

Cyril

New member

Equipment
B1750HST
Apr 9, 2012
4
0
0
Ireland
Bacterial and/or fungal slime is something I never considered and this Kubota was in storage for about 4 years before I got it, so I'll definately give it a try! Thanks for that.
 

Cyril

New member

Equipment
B1750HST
Apr 9, 2012
4
0
0
Ireland
Well as it happens the fuel cap is long gone, I replaced with the cap from a 5 gallon (25Litre) drum with an air hole in it and not exactly a tight fit! Thanks Hodge
 

alchemysa

Member

Equipment
B1550, backhoe, 4in1 bucket, rear mower.
Jul 1, 2010
49
0
6
Australia
What do you mean by 'loses power'. Does it lose engine revs or does it just lose driving power? Have you checked/cleaned the mesh filter to the HST. A blocked filter can bring one of these machines to a standstill as the HST is starved of oil.
 

Cyril

New member

Equipment
B1750HST
Apr 9, 2012
4
0
0
Ireland
What do you mean by 'loses power'. Does it lose engine revs or does it just lose driving power? Have you checked/cleaned the mesh filter to the HST. A blocked filter can bring one of these machines to a standstill as the HST is starved of oil.
Well I mean engine power as it feels like the throttle is cut down. Went mowing about 1.5acres last week, and it was very bad power wise intermittantly, only mowed half of it. So I got out the owners manual and reviewed every section in detail on fuel lines etc. The manuals are very detailed and I found out how to bleed the system, went to do it as a check and found that the single bleed valve on the fuel pump was half open...Bingo!!! Bleed the system and tightened it and went mowing another evening, much better even under heavy conditions. Was delighted until it then died completely again about an hour in, I bleed the system again & away.... Over the next hour it air-locked 3 times! So the open bleed valve was giving me the varying power outputs first, that's sorted, but I must have an air leak into the fuel system that now only appears to affect when working continously under load.. I have no evidence of any fuel leaking on any of the hose pipes so not sure what I should tackle next. Possibly the bleed valve is leaking slightly? Thanks for your reply.