I have a 1999 bobcat 773f series, once my engine is warmed up the rpms drop off under load then even just running around and the unit will hardly run. It will even die sometimes. I've replaced all fuel lines and primer bulb, fuel filter. I read one thread that said if i could use the primer bulb to keep the rpms up then i should change the pickup pump, needless to say it didn't solve my issue. I also have installed a clear fuel filter in the fuel line in front of the primer bulb. So i think i'm going to hook a gal. jug straight to the primer bulb and see it that makes a difference, if it helps then i can assume that the fuel pick up line is my issue ? Any one have any other ideas as to what i should do. thanks for any ideas james
Fuel pickups are a common issue Mine would run fine full and get progressively worse below 3/4. G series but probably no different.
Thx for your suggestion.
As a follow to my issues with my bobcat, I unhooked the fuel tank from the system and hooked a qt. bottle just in front of the primer bulb and tried to rule out the tank and the lines from it as possible issues for the motor bogging down when it fully warmed up. This didn't change a thing as far as the unit still bogged down and died, so at this time i'm out of ideas as to what it could be. Does anyone know if the injector pump could cause an issue like this, where it runs fine till warmed up then just falls on its face. Thanks again for any input.
Does it have the small Kubota 4cyl. engine.?? w/ the small PFR style inj. pump.?? Why havent u changed the supply pump.??
If you mean the small pickup pump I’ve changed it. Ibe changed everything but the injectors and the main injector pump so what I wonder is why it runs fine till it warms up then it has the issues I’ve mentioned Thx jc
I cant remember right off what the model of the engine is but it is about 40 h.p so I'm sure it's the small engine. I'm Mechanically incline so with that thought i'm not sure how the main pump can run right then have a issue after warming up? but I don't know enough about injectors to be so sure they couldn't have an issue after warming up. I appreciate any thoughts thepumpguysc. Thx
It really sounds like it’s sucking air or not getting enough fuel. Does this Kubota have a mechanical lift pump? It would be mounted on the side of the block. I would recommend trying to isolate the problem. Run a line into a can, to a cheap 12v pump, then straight to the filter mounted on the machine. Pull the return line from the injectors back into the can. This way you know you are forcing fuel into hp pump. I assume you have cracked all the lines and have steady flow, and checked for any difference in how it’s running as the injectors are cracked.
Bobcat 773 F series should have a Kubota V2203 engine. You need to make sure the fuel solenoid is pulling the shut down lever fully into the run position and verify the prime bleed screw on the injection pump return line is screwed in fully CW.
Have you verified the possibility of water contamination in fuel tank?
Thx for all of your reply’s, I have changed the lift pump that supplies the main injector pump and I have hooked the system to a qt bottle of diesel at the primer bulb and ruled out both things(water hoses ect) so I can’t believe the injectors or the injector pump would work fine one min then give me an issue of bogging down/lack of RPM’s and or power
So I’m open to any more ideas as I appreciate any and all suggestions thx
THE SHUT OFF SOLENOID GETTING HOT & BREAKING DOWN.. ALLOWING THE PLUNGER TO HIT THE PUMP RACK..?? {Stupid cap lock} Take the solenoid OUT of the picture.. stuff some paper towels into the hole if ur worried about oil splatter & run the pizz outta it..& report back..
I've now tryed a bottle hooked right to the primer bulb but haven't considered the solenoid as being a possible issue best it runs for a few min then when warmed up the problem of loss of rmp's and power happens but i can see where if the coil is breaking down maybe its not holding the shut off fully open and could be my issue. Tonight after work i will tie it open and see if that solves my issue so once again thanks to all that are offering ideas and i'll post the results of the test
As I mentioned previously, make sure that fuel lever (red arrow) is fully in the RUN position while the engine is running, and make sure the bleeder knob (item 1) is fully closed CW. You might consider disconnecting the return hose connected to the bleeder valve and add a piece of hose to the bleeder valve going to a container so you can monitor how much leakage is going through the bleeder valve with engine running.
i will try your idea willie as i'v run the machine and checked the shut off valve and it appears to be rock solid as far as not choking the fuel flow down. But i haven't tried running the bleeder line back to a bottle to see how much is coming by. Should there be some coming by, or none at all?
Today I’ll test the bleeder valve blow by, but along with that is it possible to have the injectors and or pump go down on performance once the machine is warmed up? I struggle with this since there both mechanical in design Thx again
there is 2 spring on the back of the throttle lever on engine that connect the speed liver to the Governor in front case. maybe they became weak. to access them, you must open solenoid, then 4 of 10mm bolt on throttle lever.(exactly on plate that red arrow shows one above picture) then you could see those springs.
Ok I’ll look thx frog for the help been very hard to figure out
I haven't checked that before myself so I don't know, only thinking you mentioned it starts fine then has problems once it warms up, my thought was monitor the return flow from the bleeder valve and see if that flow changes as it warms up.
Ok I see what your saying thx again as I’ll check it tomorrow
At this point, from what you've done thus far, I have no idea what's going on, never seen something like this before, thepumpguysc knows far more about injection systems than I. Just throwing out ideas here.
Yes at this point the only thing I haven’t done yet is pull the plate the throttle is hooked to and check these springs that are under there I’m not sure I’ll know if there weak or not I suppose they’ll just let the gov. Ideal down (not sure)
what kind of filter? I'd remove it for testing purposes, you still have the stock fuel filters in place, right? CAN you keep this running better by pumping the priming bulb when it's stalling?
I’ve bypassed the in-line I installed and went straight to a bottle and when it does stall out, you can keep it running by bumping the primer bulb When this first started to happen I changed the canister filter then it didn’t help so I the put the inline clear filter on to see if anything was coming from the tank, cause I had already drained it out also
Sure seems like either the transfer pump isn't working, or it's sucking air between the bulb and the transfer pump. How about remove the primer bulb? and anything else downstream of the transfer pump and run a hose to your fuel jug from there.
ok delmer i'll try this as well so i'll run a bottle straight to the lift pump and bypass everything. does anyone know if there's an after market elec. lift pump that can be put in the loop and do away with the lift pump or wood this just flood the machine.
You shouldn't need a different lift pump, such as an electric pump, the mechanical lift pump fitted on that engine works flawlessly on tons of Bobcat machines out there. Of course, it's your choice, you could delete the mechanical pump and install an electric pump, figure out "where" to tap it into the ignition circuit to power it, my only point is why, those mechanical pumps do the task day in and day out on those machines with no worries. I know you stated you replaced the lift pump, but possibly it's faulty? It does happen. Again, I'm grasping at straws here, I'm baffled.
Ok iv'e looked into the governor and moved the linkage back and forth and at least when its cold it has plenty of tension on the linkage. Just as a follow up to the hole problem as the engine warms up to operating temp then it has trouble maintaining the RPM's at a good throttle speed to operate the machine, it simply put just ramps up and down and at its low point sometimes it catches it self and ramps up or sometimes it just chokes out at low RMP's and dies. today i went over all the fuel lines and checked for vac. leaks, which i found none as i loosend some of the hoses i could here the lines sucking in air so the vac. on all the lines seam to be fine and not sucking air.
Is this and engine that could be affected if return line is plugged ? I've seen worn injection pumps / governor's drop say 500 rpm but never stall this sounds like fuel starvation or intake is restricted. What color smoke when it dies?
I've had everything apart but the injectors and the main injector pump and the smoke is perfect, it shows no signs of blow by or anything major. My question is it runs fine till its warmed up then it stalls and has no power, even dying at points. Is it possible for a set of injectors to work good when cold then go to hell after the motor has run for 5/10 min.s Then if not does this theory apply to the injector pump (could it be fine one min then go south after warming up) Then also would these issues be fine again once the unit is cooled back of then return as it warms up again. I'm just not an expert on the injectors or the pump. Thx for any input
Just as a follow up, my machine has 2700 hrs on it the injector pump could be bad but should give many more hrs than it has on it
They put those Kubotas in Carrier refer trailer units, they go 20,000+ hours. Usually never get rebuilt, get a new trailer at that point. Rmllarue asked about smoke, is there black smoke? or at least visible smoke when the engine is warm and surging? If there is, then the engine is getting fuel, if there is not visible smoke, the engine runs when it gets fuel and slows when it's not getting fuel. That's a simple and reliable inline injection pump, I don't know of anything that would cause this inside the pump. It's a mechanical governor as far as I know, so highly unlikely to break in a way that acts up when warm. An injector that's leaking back combustion into the return could do this, but that's unlikely in my guesstimation. You know that pumping the priming bulb will keep it running, you could try an electric pump to see what that does, but you already know that the priming bulb will do that. It almost has to be a suction air leak, or a weak transfer pump, or a blockage somewhere. Rubber hoses will often work cold and then leak when warm. Maybe an o ring is doing the same thing? Before even thinking of touching the injection pump or injectors, put a pressure gauge on the fuel inlet to the injection pump, or close to there, and see what the pressure does from cold to warm.
I'm scratching my head and thinking the same as you Delmer. Injectors go bad, but not all of them at once, warm or cold. Same with injection pumps, I've never seen anything that makes one flip out when warmed up. Don't mean it can't happen, just never seen it. I agree, stick a new fuel hose on that supply fitting to the injection pump, hook an electric pump on that hose, then another new hose from the electric pump to a clean fuel container. See how it does then cold to warm. If it doesn't falter, then you have something wrong with the supply system of your machine. That's the way I see it.
James, Any chance that your primer bulb is collapsed or partially collapsed after you have stalled out? In the video links below, this fellow had a Bobcat 853 with a fuel starvation problem, with his engine starving out, losing power and stalling after getting warm. When he did prime it before stalling, it ran for 5 minutes and then stalled out again when warm. Sound familiar? In his case, it turned out to be a restriction in the fuel pickup from the tank ... sounds like it was a fuel strainer / check valve that was plugged (or restricted) with rust or debris. He ended up blowing the plugged strainer / check valve off into the tank using compressed air and installing an in-line fuel filter, in-line check valve and an electric fuel pump to get it running again. Have a look at Video 4 first to see the result and then the first 3 videos for some of the details. Even if this is not your problem, his videos might give you some more ideas to troubleshoot your problem further. Regards, 3CW Video 4: Video 1: Video 2: Video 3:
Here is a Bobcat 843 video showing the fuel pickup. I am not sure how this compares to your 773?
And there is another vote for the addition of an electric fuel pump here ... but under different circumstances. HeavyEquipmentForums
I was going to suggest a bad primer buld the other day but got side tracked.. sorry bout that.. They're easy to spot in most cases.. IF your going to use an electric pump, get 1 w/ NO MORE than 10 psi.. or you'll flood the pump & it will leak fuel into the crank case..
thx threecw i'm at work now but when i get home ill try some of these ideas. cant tell all of you haw much it means to have some people willing to offer suggestions to solve this issues so thx again
Here's a follow up to installing a gauge on the fuel line. I installed a 0-15 psig gauge right in front of the injector pump, So when i started the 773 it was drawing between 3.5-4.0 psig of fuel into the pump. after it warmed up, some 5 min or so at 56f temp out doors, it started to stall and loose hp. at that point, and the gauge was down to roughly 3 psig or less. I wish it was liquid filled gauge but its not so it does bounce around a little. So it did appear to be down a little on flow, so I have a brand new pick up tube ect. for the tank and am going to install it and see what happens then. Does anyone know what the minimal psig to the injector pump must be to operate the machine properly. And as usual I can't tell all the people who have been offering suggestions to solve my problem how much I appreciate all of your help thx again.
6-8psi. It’s either a faulty/dirty filter or a weak lift pump.. I assume it’s a cam driven supply pump.?? The love might be worn down a smidge.. I would put on an electric pump & be done.. No more than 10 psi.!!!
Ok im on ebay now and going to order tonight Thx thepumpguysc
Wait, what? Why are we talking about the pickup tube inside the tank at this point? You're not there yet, back the truck up skippy. Again, I repeat what I stated previously. Disconnect the fuel supply hose to the injection pump and fit a new hose to it. Run that hose straight to the outlet of the mechanical lift pump. Connect another new piece of hose to the inlet of the lift pump and stick that hose in a clean container of fuel. Start/run engine until it warms up. If it falters, disconnect the mechanical pump and install an electric diesel pump in its place, try again. If it still falters, the problem ain't the pickup tube inside the tank.
As to the wiring I was thinking I could wire it right in to the same harness for the fuel cut off solenoid thus when one is open the pump is on. what do you think folks.
willie i did run it to a bottle straight to the lift pump and then straight to the injection pump and it didn't help, but what I was saying is i have a new tube and screen so I might as well install it to since I'm going into it for a electrical pump
sorry for the confusion willie
Does any one have any thoughts as to the best place to power the electric fuel pump when it arrives this week
I like this suggested method to wire a fuel pump using a relay with an oil pressure safety switch in the wiring circuit. - With the ignition turned on and the engine not running, there would be no power to the fuel pump. - When cranking (with no oil pressure yet), the starter circuit would activate the fuel pump relay. - When the engine has started, the oil pressure switch will activate the fuel pump relay from the ignition switch. - If you lost oil pressure, the fuel pump will turn off. - If the ignition key was left on (with the engine not started), the fuel pump would be off. A wiring diagram for this is shown below: See some more tips for placing and wiring a fuel pump here: http://www.how-to-build-hotrods.com/electric-fuel-pump.html There are also other wiring options shown in this attached Holley Fuel Pumps Installation Instructions:
Thx Threecw
Well folks I got the new electric fuel pump and hooked it up after starting my machine up the fuel pressure was running between 7-7 1/2 psig, so I thought things looked pretty goodI let the machine warm up and ran 200gal. of water to my cows. Which took about 20 min of run time so I thought things were going well, then the machine did the same old thing, in that it started to bog down and it wasnt long after it died with all of the same symptoms that it has had for the last few weeks.I completely bypassed the lift pump and hooked the new elec. pump in it place. I did note that when it started acting up that the fuel pressure was down to around 6 psig . so now everything has been ruled out but the injectors and the main injector pump so my question now is what should i try next. I'm not sure who could preform a pop it test on the injectors of if i should replace them or what. once again im open to any thoughts. Thx
Sounds like there’s sumpin in the tank.?? Unless u took it out OR ran from an auxiliary tank..
James, Sorry to hear that you are still having problems. A little brain storming here …or possibly brain farting! As you said in your post #4, before you installed the electric fuel pump, you eliminated the fuel tank and ran from a quart bottle … but the engine still it still bogged down and died. So that should eliminate the junk in the fuel tank theory … or the bad fuel pickup theory. You said in Post #50 your engine ran for 20 minutes successfully while you were watering cows … a question for other readers of the thread … does that 20 minutes of good running eliminate a fuel injection problem or is that still a possibility after the engine warms up? You mention in Post #40 that with your mechanical fuel pump, the engine ran at 3.5 to 4 psi fuel pressure and the engine started stalling at 3 psi. You also mentioned that the fuel gauge was “right in front of the injection pump”. But with the electric fuel pump in Post #50, it ran at 7 – 7.5 psi and started acting up at 6 psi. I “assume” that you had your fuel pressure gauge installed in the same place. Base on those pressures, you are getting fuel delivered to your injection pump and your problem is NOT with fuel delivery. What other sensors will shut down an engine after it warms up? Sensor after the air cleaner? Faulty oil pressure sensor … oil gets hot and shuts the engine down. Are there any other sensors that will shut down an engine (check your wiring diagram if you have one)? This is a real mystery … but it could end up being something relatively simple. “Assuming” it is NOT the injection pump based on the 20 minutes of good running and “assuming” that fuel deliver is NOT the problem … what else will shut down an engine?
I can say the gauge is in the same location for all testing, It doesn’t seem to me to be a cut out shutting the machine down because it will big down/pick up a few times then die or just idle so poorly no mater where the throttle is/wide open or useless down At this point I wish I new how to do a pop it test on the injectors, or just new more about both the injector pump and injectors
Why is the pressure dropping from 7 to 6 PSI? when the engine is not under load, so not using a lot of fuel ,and not smoking to prove it's not using a lot of fuel. With the electric pump, the pressure should only drop if the engine is loaded up at full speed and blowing smoke, and even then, the engine is not using a lot of fuel compared to the fuel pump capacity. If there's air getting sucked into the fuel, it will do this, mostly maintain the fuel pressure, but not run right. The injection pump is a very small piston pump, extremely bad at pumping air. Check the fuel return for air, use a clear vinyl hose into a jar of fuel to see bubbles. The injectors are easy, take them to get checked, or just replace, but I don't think that's likely the issue. Thepumpguy will say the injection pump could be worn out, but I don't think we're there yet either.
As far as the fuel pressure dropping off I’ve seen the throttle wide open or at idle When it bogs down But I will try the return line and see how it goes The biggest thing I struggle with again is why injectors and or pump being fine when cool and struggling when warm
If there is air in the return line I will be surprised since I’ve ran the machine from a jar to the lift pump to rule out all the lines up to the lift pump
When it bogs down and stalls, will it start up right away again? Does it try to start ... cough and sputter, attempt to start but will not start? Or does it just turn over with no result? If it restarts, how does it act? If it does not restart when warm, will it restart easily when cold (without any other intervention)? How does it act then?
It will start right back up but seems like most of the time it just runs like **** then it might catch its self and come up to rpms but when you then move it will bog again maybe even die But after it cools off and hr or so it runs fine again till it get up to temp. And it’s never even getting close to over heating
Some brainstorming to eliminate what might have been overlooked: Have you checked that the fuel cap vent is working? Pulled the fuel cap after stalling to ensure no vacuum on the fuel tank?
No I haven’t done that but that’s an easy check thanks
When I get home from work today around 430 central time I’ll check thx
I ran the machine last night but only for 15 min never got up to full temp cause we had snow and ice falling from the sky. winter just wont leave. so if its a little warmer tonight i"ll try again
Well for the first time in a week the temp came up enough yesterday to get the machine back out and see what would happen. After it was fully warm it did run better for say 30 min, then it went to bogging down and stalling then dying so I got out and loosened the fuel cap and seen no results. the fuel pressure was staying above 6-1/2 psig through the hole test. So I"m still at a loss as to whats going on. There doesn't appear to be a lot of smoke really at any point, and certainly no black visible smoke as it really is running very clean. When it does die it does seem to be worse when try to put machine under load I.E. moving ect rather than just setting still but even then it still struggles mightily. Once again I'm just not a expert on injectors and or pumps Thanks again guys for any suggestions
This is a serious head scratcher .. Just to catch everyone up.. u bypassed the fuel tank & ran out of a jar.. A gallon jug like an old oil jug probably woulda been better.. but nevertheless.. & it died.. Then u hooked up an electric pump & it died.. Are u doing all these tests w the AIR CLEANER REMOVED.? That would be my 1st thought.. Is there any kind of an electric solenoid to shut the fuel system off.? If yes, either remove it or straight wire it off the battery if possible.. if it’s a 3 wire sol.. don’t straight wire it.!! With an electric fuel pump and a good fuel supply (gal. jug) And w the air cleaner removed and a shutdown sol. removed.. It autta run fine.. Try all those things all at once & see what it does.. Can u post a pic of the fuel system, including the injectors.??
I haven’t ran the machine with the air filter out at any point but I’ll try that Also I have tied the fuel stop in the open position and it didn’t help
I haven’t ran the machine with the air filter out at any point but I’ll try that Also I have tied the fuel stop in the open position and it didn’t help
Can u send a pic..?? It sure would be helpful.. I’ve had fellas swear up & down they “adjusted” the sol. correctly & their so adamant about it they wanna fight.!! & when they show up the dam thing isn’t pulled or pushed enough & when I “fix it” they’re just amazed how well it runs.. So a pic sure would relieve any doubt & we/I can move on.. If a pm would be easier (phone #) we can do that.. Just snap a pic w your phone & hit send.. lemme know.
I understand that your fuel pressure gauge is installed downstream of the fuel shut off solenoid and just before the high pressure injection pump ... is this correct? You said your "fuel pressure was staying above 6-1/2 psig through the whole test". Was the pressure fluctuating any during the test? How about just prior to shutting down ... did the pressure change then. If the fuel pressure was rock solid, than any component upstream of the pressure gauge should be working fine ... eliminating any blockage in the fuel delivery system and also eliminating the fuel shut off solenoid I would deduce. That being said, I think it would still be good to check out the fuel shut off solenoid ... despite what your pressure gauge says. More brain storming - we know you show pressure coming from your new electric pump. Just for shxts and giggles, I would disconnect the fuel supply line going into the injection pump and measure the rate of fuel delivery. Use a cup of a know volume and measure the time to fill or partially fill it to determine the fuel pump rate. It would be worth doing when the engine is cold and again after it has failed after warming up. If you have a good fuel delivery rate both cold and warm, then that eliminates a lot of guessing. And some more brain storming - How about sensors ... like I mentioned earlier, perhaps a faulty sensor (oil pressure, air sensor, others?) that is killing the engine when it warms up. Does anyone have a wiring diagram for this machine to see how the sensors work? I assume the sensor would kill the engine using the fuel shut off solenoid ... but that is just a guess, not based on any personal experience.
Clark, post: 883136, member: 86515"]I haven’t ran the machine with the air filter out at any point but I’ll try that Also I have tied the fuel stop in the open position and it didn’t help
Here’s a photo of when the machine was running,
This pick was of the unit before the electric fuel pump was installed thus the pressure is only in the 3-1/2 psi range rather than the 6+ psig I have now after the eclectic pump was installed If I could figure out how to send video I would
Here’s some more pic.s These pics show the machine after it has run say 5 min it also shows how clean the engine is running I believe the 3 picks are after it been running maybe 10 min
Here are the rest of the pics
The pic with no pressure is where I opened the bypass bleeder and just to see if the pressure was true and it relived it all by doing so
I was going to suggest that, until I saw the last pic.. lol I have 1 on my bench right now.. .. & always get confused for some dumb reason on which way to shut off the bleeder..?? Its definately a supply problem.. The pressure need to be as hi as 10psi to feed that pump.. The test spec for that pump says 6-8 psi inlet fuel pressure at full load..{constant pressure} So either the electric pump isnt strong enough or your mechanical supply pump is bad..
Meaning injector pump?
Please re-read my post slowly..
Gotcha so I may need to get a elec. pump with just a little more heart in it.
Yes Sir.. U have 1 thats a 1-3 psi.. u NEED a 10psi.. MOST of them dont hit that target range & theyre 10-12.. If u can find 1 thats 7-10 that would be good.. IF your just diagnosing.. u can certainly use a 10-12.. most of'm are on the lower side anyway.. so a 10-12 will prob. put out 8-10.. which is perfectly fine.. The thing I find is, people have a Holley pump hooked up that blasts 30psi & wonder why they're getting fuel in the oil.. lol Have fun at work..
Just so you know the pump I bought is much like you said I got a 7-10psi and it’s putting out about 7 or 7-1/2 psi So I’ve been looking at 10-12psi pumps
Also I took care not to get something that would be more than 10psi based on what you said about mixing oil and fuel
I see from your photo that you left your old mechanical pump on the engine but left it disconnected. Does anyone have experience doing this? I am not sure if running the old mechanical pump "dry" will result in the pump seizing up at some point and causing a problem ... or perhaps it is safe to do this ?? Does anyone have experience with this? So where you are at, the engine stalled when it warmed up with the original equipment mechanical pump with a fuel delivery pressure of 3 psi. And the engine also stalled when it warmed up with your new electric pump with a fuel delivery pressure of 7 psi. I would think that you are getting fuel to your injection pump ... but would still do the fuel pump testing that I suggested in post #68.
Here is an interesting read that might give you some more troubleshooting ideas: HeavyEquipmentForums
Well folks I know its been a while since we've talked but my machine hadn't been used much since I've installed the 2nd. electric pump on it (I'm now running around 9psig) and the unit was doing better than ever then this weekend I used it to move a little dirt around the farm. (The temp was 85 outside) and about 30 min.s into using it it started to stall out again and died twice. At that point I let it cool down some for 45 min then completed my work and parked it This was yesterday that this all happened. So now once again I'm not sure what my next move is. Any suggestions folks, no bad ideas at this point. Thanks
Can you determine what position your fuel solenoid is in after your skid steer shuts down due to high temperature? You will likely need one person on the key and another holding on to the solenoid to check this.
i will have to do the 2 person thing and get it warmed up and have someone try to keep it running while i look over the shut off solenoid.
James, Did you get your problem sorted out on your Bobcat yet? If not, here is a recent thread with a similar problem ... in this case it was the injection pump. Read about it here ... HeavyEquipmentForums
Thanks, Having same issue on mine, gotta check mine..lots of useful info here..appreciate.
DID YOU EVER GET IT FIXED? I AM HAVING THE SAME ISSUE WITH NY 1995. 773