Bobcat 773 fuel issue

[Easttnlc]

First off I'd like to say, this is a great website with lots of good information.

I know a few people on here have had similar issues as I'm having but nothing narrows down my problem. Machine is a 2001 773 with the Kubota V2003T engine and I'm experiencing a loss of power and a rough idle although at higher RPMs and trying to turn a 360, the machine dies, also at high RPM and sitting everything sounds good but you hear almost like helicopter effect. Like most, the pickup tube had broke off and has since been replaced, all new air filters, fuel filter, and oil filter and machine still has this issue. I tried running the machine off a 5 gallon jug of diesel and rigged a primer bulb to let the engine run off of that and it acted the same, so hopefully that eliminated a few things. The exhaust does not smell like a diesel should, it almost smells like a charcoal grill. The only smoke it puts out is on start up and very minor under a load, probably no more than a normal operating machine. My question is, could something have been sucked up into the pump or clogged the injector since that tube broke off? Any help is greatly appreciated and if you need more info or details I'll do the best I can to describe it.

 

[dave esterns]

there should be a small 80 dollar round fuel lift pump above the fuel filter you could try replacing...

 

[Easttnlc]

I'll look into that, thanks!

 

[crewchief888]

hard starting when hot?

:drinkup

 

[Easttnlc]

I would say that it seems like it takes a little while longer to crank when it's cold and hot than a normal running machine does.

 

[crewchief888]

may have a bad lift pump.
the pumps dont deliver much pressure to start with, and 12 year old machine.....


:drinkup

 

[Easttnlc]

Is there any way to test the pump or maybe something could be stopped up? Also, what is the round knob on the pump, where the fuel line goes in?

 

[Delmer]

You just need a pressure gauge to test the pump output pressure. A gauge like 0-30 psi should work, lower would be better, hook your gauge to a fuel hose to the output of the lift pump and crank it to see what kind of pressure you get. Then disconnect the gauge, put the hose in a bottle, crank it ten seconds and see how much volume you get, then find what it should put out if the pressure or volume is not obviously low.

I'm curious of the "helicopter" noise, is that like one cylinder misfiring or all of them sounding different?

 

[Easttnlc]

The helicopter noise was the only description I could think of. Another description would be like a push mower. I know it sounds crazy but that's the best way I can put it. It's got me puzzled too.

 

[crewchief888]

Is there any way to test the pump or maybe something could be stopped up? Also, what is the round knob on the pump, where the fuel line goes in?

those pumps only put out 2 or 3 PSI.

if you mean the little round knob on the injection pump where the return lines hook up..
kubota calls it a "jet valve" manually open it to bleed air off the top of the inj pump after replacing filters.

if you havent opened it, and manually primed the system you could (and probably do) have some air trapped in the pump.
that will cause hard starts, hot or cold, but more often when cold, after the machine has been sitting for a while.

 

[Easttnlc]

Which way is open to bleed the air? With not having any manuals and this being my first kubota engine, I thought it was a fuel shut off valve. Everytime I've primed it I just crack the screw and squeeze the bulb, so in addition to that, I need to turn that knob open as well?

 

[crewchief888]

Which way is open to bleed the air? With not having any manuals and this being my first kubota engine, I thought it was a fuel shut off valve. Everytime I've primed it I just crack the screw and squeeze the bulb, so in addition to that, I need to turn that knob open as well?

counterclockwise to open
open it, squeeze the primer and few times and close it back up.

on those engines you really dont even need to use the bleeder screw on the filter housing to remove the air. it'll push out when you open the bleeder @ the inj pump

:drinkup

 

[Easttnlc]

Thanks for the help, I'll give that a try and see if it makes a difference and keep you posted.

 

[Easttnlc]

Well I finally had time today to work on the machine and so far the problem has only gotten worse. I removed the injectors and took them to City Diesel here in town to have them tested, all came back good. I replace them back in the machine and after awhile of trying to start it, it fires up but now runs even worse and is blowing black smoke constantly with no sign of letting up. I'm at a complete loss... Why would one min the machine doesn't smoke and after I remove them, have it tested and put them back in, I get heavy constant smoke?

 

[willie59]

Did you replace the lift pump?

 

[Easttnlc]

Not yet, that will probably be my next task. They are suppose to get me a price on that today.

 

[crewchief888]

do you have good, clean fresh fuel ?
completely plugged air filter could cause the heavy smoke

it's not likely, but you could have an issue with the turbo...

:beatsme


:drinkup


:drinkup

 

[Easttnlc]

The fuel is fresh, both new air filters and the intake tube for the turbo is clear.

 

[willie59]

Does the engine run rough right from start up, and continue to run rough at idle?

 

[Easttnlc]

Yes, it runs rough right upon start up, it was that way before I took the injectors out yesterday to have them tested and it still runs rough had has that disting knocking sound only now, it pours black smoke upon start up. I'm wondering after they tested it, if somehow an injector got stuck open??