V1702 injector pump problem!

[bobcat]

I have a Bobcat with a Kubota V1702 engine, about three years ado I was having a problem with it wanting to die out on me. That problem seemed to fixed itself as it had been running trouble free for the last three years until today. The problem has come back, I have checked the fuel lines, the fuel pickup tube in the fuel tank, replaced the fuel filter, and replaced the lift pump. When you open the lines at the injectors there is air in them, they will not completely bleed (the fuel will have air bubbles in it). After all that I pulled the fuel supply line off from the injector pump, and it shot fuel everywhere, so the injector pump is getting plenty of fuel. Is there a filter of some sort at the inlet of the injector pump? or is the injector pump going to need a rebuild?

 

[North Idaho Wolfman]

I have the 743 too,
Did you replace/ check the fuel bulb?

Check the return lines and make sure they are clear.

The inlet line to the injection pump should have a slight pressure on it if it was ran recently.
It's rare to have an injection pump add air, so it's more likely that either the pick up, fuel line, primer bulb, filter assembly, or lift pump is sucking air into the system.
My bets would be on the pick up screen/pipe, Fuel lines or fittings up at the top of the tank, or possibly the fuel primmer bulb.

I have all the manuals for the 743, if you want copies, just PM or email me, (Just click on my name on the right to get the links).

 

[hodge]

I second checking the primer bulb- they are cheap to replace, and crack with age. Mine had a split draw tube in the tank that gave me grief, as well as the original fuel filter glass- it was chipped, and it was very difficult (partly due to having to stand on your head to get your arms in there and work) to get it to seal. I replaced it with a newer housing and modern filter.

I would say you have an air leak in the system, since it went a way for a while and it's back. I doubt you would have gotten 3 years out of a bad pump.

 

[bobcat]

I didn't have another primer bulb so I put one of those little 12 volt electric fuel pumps for diesel in place of the primer bulb. So it's not a problem of getting fuel to the injector pump. I wired the electric pump to the key, and its getting fuel to the injector pump, I made sure of that. There is no water in the fuel, and I put a new fuel filter on it I keep a couple of extra fuel filters on hand. No water was in the old filter.

 

[North Idaho Wolfman]

I didn't have another primer bulb so I put one of those little 12 volt electric fuel pumps for diesel in place of the primer bulb. So it's not a problem of getting fuel to the injector pump. I wired the electric pump to the key, and its getting fuel to the injector pump, I made sure of that. There is no water in the fuel, and I put a new fuel filter on it I keep a couple of extra fuel filters on hand. No water was in the old filter.

Ok what I do know is that you should not pressurize the fuel running into the injection pump, that is what your doing with an electric fuel pump, so all bets are off as far as injector pump issues.
Now that's not to say your not just pumping air into the system, this could again be caused by a bad pickup tube fitting or line.

I would replace the pickup tube, line, and put the bulb back in it.

 

[bobcat]

I managed to find a new primer bulb, put it back in-line (took the electric pump out), and filled the tank full of fuel (it only took 3 gallons to top it completely off). The mechanical lift pump is providing fuel to the injector pump. Tried to bleed it, and its a no go. All it will do is start, and run badly for a few seconds then quit.

When I was having problems with it 3 years ago I replaced the pickup tube, and everything (even replaced the glass bottom 2 piece filter with a spin-on with a drain). That still didn't fix the problem, after about two months afterwards living with the problem which wasn't as bad as it is now (I only use it on weekends at the farm) it just quit giving me problems. I'm at a loss on this one

 

[North Idaho Wolfman]

Either you have a break / or crack in a line, fitting, or filter or possibly a clogged part like the pickup screen or filter, or you have contaminated fuel, either with water, gasoline, or algae / sludge.

One thing I had with mine was a bad bleeder valve at the side of the injection pump. Pull the bypass line off and make sure that no fuel or air is bypassing the pump.

http://stores.allskidsteers.com/oem-bobcat-fuel-bleeder-valve-for-743-6598102/

Start by eliminating possible issues, feed the injection pump directly from a hose and a funnel or bottle, if that works keep moving back through the system till the problem reoccurs.
Note: Remember you will need to bleed the system between each new fuel test setup.

 

[hodge]

Bacteria contamination of the fuel is a possibility- I had that on a Dodge truck. There was enough bacteria built up- a piece about the size of a quarter that was inside the screen on the tank pick-up- which would float around, and sometimes find the intake and cover it, cutting off fuel flow. You might want to start over, pull the pickup tube from the tank and check it, then go from there through the system to the pump. It sounds like something is either disrupting the flow of fuel, or air is getting in.
You could also take a can of diesel fuel, and run a line from it straight to the lift pump. Then, see if it will start. If it will run off of the fuel can supply, then you know the problem is somewhere in between the regular tank and the pump.

 

[bobcat]

I checked the bleeder valve, it does work like it should. Took a good clean 2 gallon plastic fuel jug, drilled, and tapped it at the bottom for 1/4" npt hose barb. Hooked it up like a I.V., put a gallon, and a half of fresh diesel in it. It still does the same thing.

 

[hodge]

I checked the bleeder valve, it does work like it should. Took a good clean 2 gallon plastic fuel jug, drilled, and tapped it at the bottom for 1/4" npt hose barb. Hooked it up like a I.V., put a gallon, and a half of fresh diesel in it. It still does the same thing.

Ok- now you know it is somewhere on the engine. Lift pump (not likely, since you replaced it and know it's pumping fuel), injection pump, or injectors.

 

[Tooljunkie]

I had a bobcat come to me with what was assumed to be an injection pump problem,it loads up and stalls. Then it would crank slow and smoke like it wanted to start. Wait an hour and same thing. Looked like air in injector lines. Certified diesel tech said replace pump.

A shot in the dark here but is there a chance auxilary hydraulic was activated?
That machine, right stick was snapped over to right, deadheading pump.

 

[bobcat]

A shot in the dark here but is there a chance auxilary hydraulic was activated?
That machine, right stick was snapped over to right, deadheading pump.

That is not it either, I made sure of that. I took the injector pump out, and I'm having a diesel injection repair shop test it out (where a friend of one of my friends work). If it doesn't test good they are going to open it up, see what's up, and what it will cost to fix it. Their waiting list is 2 days, so now I wait.

 

[bobcat]

Turns out the injector pump needs a rebuild ($590.00) Bobcat dealer wants $780.00 plus shipping.

 

[North Idaho Wolfman]

Check with these guys if you haven't committed to the rebuild yet.

http://oregonfuelinjection.com/index.php?page=sec/rebuilt-injection-pump-injectors.htm