tricks to getting the fuel system bled?

escavader · Sep 20, 2006

I dont mean to ask in two different places,but i wanted more ideas .I changed the two inline filters on my little kubota,and now i got alot of air,ive bled and bled it runs ok for the first 1/2 hout then flutters and gets worse and worse.Mt book says simply turn on the key.... dont work,my neighbor who is a diesal mechanic,and i have been cracking the injector lines to get it out.He explained sometimes a system can be a pain,and takes alot of trys.He sprayed either around the filters and checked them out he said he thought they were fine.It is improving i guess,but what a pain.He even has told me a story about pressurizing a fuel tank to force the fuel out,on a dozer.So any body got a trick up their sleeve?I bet ive cracked them lines 20 times now.If this is what maintanance is gonna get me ,ill run it til it puke
whats your advice?
ALAN

Dirthog · Sep 21, 2006

If it runs for the first 1/2 hour then the system is bled out already. You have a leak someplace and it is sucking air or the supply line is sucking shut.

caddelma · Sep 21, 2006

Dirthog said:
If it runs for the first 1/2 hour then the system is bled out already. You have a leak someplace and it is sucking air or the supply line is sucking shut.

Had the same exact problem on my Lenar. Ran for a little while then lost power. It was either a blockage or air leak (leaning toward air leak). In my case the shutoff valve under the tank was very loose (finger loose), but not loose enough to leak fuel. Tightened it all up and been running fine.

Soundguy · Sep 21, 2006

I also think that if it runs for 1/2 hour, it is 100% bleed. You may have an air leak at a fuel filter.. perhaps bad oring.. Or your fuel tank is not vented and is creating a vacume.. or fuel line blockage.. / valve blockage.. etc.

Soundguy

escavader · Sep 22, 2006

I think you guys are right.Im gonna put different clamps on the fuel filters,i dont like them wire ones.THANKS
ALAN

kevincook · Sep 28, 2006

Does it run normally for the 1/2 hour or is it still running rough. The fuel lines can be a real pain sometimes. If it runs normally at all rpm's for 1/2 hour then you probably have a leaking line.

Kevin

DieselPower · Oct 1, 2006

If all else fails and you suspect a air suction problem in your fuel system take a trip to your local Caterpillar truck dealer. Ask to buy a special service tool that is called a fuel sight glass. It is basically a fitting with a clear sight glass in the middle of it. It hooks in line with the fuel supply line to the injection pump. If you see bubbles in the glass you have a air suction problem either at the fuel pump or before. If your engine has a primer pump that is also a suspect item. I have replaced alot of fuel primer pumps over the years that were fine one minute and started sucking air the next, then were fine again. Air being sucked into your fuel system can be a nightmare to troubleshoot if you don't plan out your troubleshooting plan in a systematic plan. Good luck.

escavader · Nov 1, 2006

Just an up date ,I changed the clamps,seems alot better,doesnt seem to be any air now.The tractor doesnt seem to sound the same on all cylinders,of course i know how it always did sound.Its been about 20 hours on the meter,since i last posted.Every now and then i can smell raw fuel coming through the exhaust.Whats going on? I got 3 months on the warrenty.Can you give me an answer or should i truck it to the dealer.Faulty injector pump? bad valve?I really need this tractor,to finish up projects before ground freezes[any time now]
ALAN

Soundguy · Nov 1, 2006

If i were coming to an end of warranty coverage, and i had -ANY- questions as to operational correctness.. then it most deffinately would get trucked to the dealer.. even if, in the end, it was just a day of driving and a clean bill of health.

Soundguy

Dirthog · Nov 2, 2006

If you can smell raw fuel comeing out the exhaust you have a cylinder that is not fireing properly either you have low compression in one cyl or more likely a bad injector.

escavader · Nov 4, 2006

HI
Ran the tractor hard for11-12 hours.Friday i added a shot of powerservice to the tank.Only flutted once in 4 hours using the hoe.Topped off this morning ,added another shot.Tractor was flawless all day.I think i had water in my fuel,what do you think?Its running like brand new again
ALAN

dqdave1 · Nov 4, 2006

If you suspect water in fuel; I would change the fuel filter again to be safe. Also if Warranty is almost over and you can truck it to dealer without major expense, do it, tell them what has been goingon; they should test injectors, injection pump and hopefully they will dyno it at the PTO to make sure it is up to peak HP at PTO

escavader · Nov 5, 2006

dqdave1 said:
If you suspect water in fuel; I would change the fuel filter again to be safe. Also if Warranty is almost over and you can truck it to dealer without major expense, do it, tell them what has been goingon; they should test injectors, injection pump and hopefully they will dyno it at the PTO to make sure it is up to peak HP at PTO

Once again sorry for posting in two different areas,but i get a better range of answers .My question is If i take a perfectly good running tractor back,and they find no wrong,wont i have to foot the bill?How long time wise will these tests take? If it aint an all day affair i might do it.I might de darned if i do darned if i dont.
Im terrified to change the filters again!!!I dont wont to start over!!!
THANKS FOR ALL THE REPLYS
ALAN

john_bud · Nov 5, 2006

escavader said:
Im terrified to change the filters again!!!I dont wont to start over!!!
THANKS FOR ALL THE REPLYS
ALAN

Alan,

Don't ge terrified. If the issue was water in the fuel, changing the filter is needed to protect your investment. It's easier and easier each time you do it. Experience is needed. And, how much worse can it get that what you have already experienced?

I would run the tank as dry as possible, then completely fill it to the very top with treated fuel.

jb

kevinj · Nov 5, 2006

Are you sure the transfer pump is working ?????

escavader · Nov 5, 2006

kevinj said:
Are you sure the transfer pump is working ?????

KEVIN,
WHATS THAT?
alan

john_bud · Nov 5, 2006

kevinj said:
Are you sure the transfer pump is working ?????

I thought the little 'botas were gravity fed from the tank to the filter then suction to the pump. No transfer pump. (right?)

Alan,
A transfer pump is often used in diesels to transfer fuel with positive pressure from the tank to the injection pump. Very nice to "power bleed" the air out.

jb

KJM · Nov 6, 2006

john_bud said:
I thought the little 'botas were gravity fed from the tank to the filter then suction to the pump. No transfer pump. (right?)

My little B7100 certainly has a transfer (or lift) pump. It is mounted on the injector pump body and is a very simple affair - a cam operated plunger style pump with flap valves. Assuming you have the same setup in your shiny new tractor, it could just be grot preventing the flap valve closing, so the injector pump eventually runs out of fuel to inject...

My road vehicle is an Isuzu powered thing - with a 4 cyl diesel engine. The lift pump on that got blocked with some contaminated fuel - it'd start and run but mysteriously die. Similar symptoms... fixing it involved rebuilding the injector pump ($$'s!).

If it is bad fuel, I'd drop the filters as suggested and have a look to see if there is water in the bottom - water should sit in the bottom of the filter chamber, below the fuel.

Cheers
/Kevin

kevinj · Nov 6, 2006

escavader said:
KEVIN,
WHATS THAT?
alan

It is the little electric fuel pump under the floor board after the first filter. The thing that makes the clicking noise when the key is on, the thing that makes the self bleed work.

Soundguy · Nov 6, 2006

john_bud said:
I thought the little 'botas were gravity fed from the tank to the filter then suction to the pump. No transfer pump. (right?)

Alan,
A transfer pump is often used in diesels to transfer fuel with positive pressure from the tank to the injection pump. Very nice to "power bleed" the air out.

jb

Sounds more like a charge pump??

In any case.. to the original poster: If your tractor is in warranty.. and you bring it in with a complaint of a problem.. reguardless if they find the problem or not.. i can't see how you would be charged for it.. unless it was a non warranty issue.. like user abuse.. etc.

Soundguy