I have an '06 435 Bobcat. I have, in the past and, currently been experiencing a fuel starvation issue with this machine. In the past it was an intermmittent problem. I first started having this trouble about 2-3 months ago. At that time I replaced the filters and removed the pump (I suspected the pump when the filters did not clear up the problem). I was able to get the pump to work fine when pumping from a fuel jug. I was not getting fuel delivery to the pump from the tank. I decided to blow, toward the fuel tank, and I felt some initial restriction, and then the pressure dropped and I could hear gurgling in the tank. This seemed to fix the problem as I have not had any more issues until the other day. Now, the machine will starve for fuel every 10 minutes. I suspect that I have something floating around in my tank, or the line is colapsing. I plan to dig into it in the morning. The tank is under the floor board so it will be a PITA to acces/remove. Does anyone have any experience with this issue? What tips would you have for me?
I'd suspect your machine is similar to mine for the fuel tank...I think you blew off the screen at the end of fuel pickup (been noted by some). Maybe the screen had crud on it. I'd aim to get that hose out and see if it has the screen on it. If not, throw a good one on it, and throw it back together. But first, make sure you have no air leaks in hose and primer bulb...I read it has been an issue for some. Doesn't have to be a big leak to cause problems. Press primer while opening fuel filter air screw and fuel should be coming out without air.... Be interested to know how it turns out.
the fuel pickup is under the cab floor, remove the floor mat, and unbolt the floor plate the fuel lines are right in front of you. the 435 DOES NOT have a screen/check valve, hard plastic tube on the steel elbow, nor does it have a primer bulb it could be plugged up in the elbow itself. there is also an inline filter between the tank and pump, it's probably plugged as well. the tank has a drain plug in it, swing the house 90* and look up under the cab, theres a hole in the frame, the drain plug and grommet in the bottom of the tank. :drinkup
crewchief888 - haha, I couldn't have been more wrong ointhead...thanks for setting it straight. I need a few more :drinkup Wonder how one primes the fuel line...
it has an electric pump and an inline filter piggyback mounted to the fuel filter mount :drinkup
I spent some more time on it yesterday. I drained the tank and checked the tank for debris. There is nothing at the bottom of the tank that would plug the pick up tube. I also ran the pump for a few hours to see if it would give out after prolonged use. It kept on pumping without a hitch (drawing diesel from a bucket and dumping it back into the same bucket). I blew compressed air through the fuel line and had no noticeable resistance, and nothing foreign was blown out. I also decided to replace the filters again (they only had about 40 hours on them). The machine ran fine for about 5 minutes. Not much of a test but I had other committments to take care of. I'm not too sure about the filter swap being the cure. I think if the filters were plugged, the fuel starvation would be consistent (that's how it has been in the past) instead of intermmittent. If it is fixed, I am at a loss as to why. Obviously this does not leave me feeling very confident that I will not have more issues in the future.
Crewchief is correct. No filters or primer bulb. The fuel pick up is easy to access and has a bevel cut in the bottom so it would take something big to plug it. I ran the pump long enough to fill a 5 gallon bucket, drawing from the tank. As you may imagine it took a while to do this and the pump had no problems. I imagine it is possible for there to be a leak in the hose, or tube, between the tank and pump. I doubt it though as I would think it would have sucked air during the bucket fill. I put it all back together today. It ran fine for about 30 minutes while I loaded and unload items from a trailer, and then mobed the 435 back to the job. I'm hoping that I have put the fuel starvation issue behind me. If not I guess I will replace the hose and pick up tube (maybe chief can tell me how hard it would be to replace the fuel hose). I have already ordered a new pump, and I will install it, just to eliminate the possibility of that being the problem. I was able to blow compressed air through the hose, brass elbow, and pick up tube so I don't think anything is in there. I did this in both directions. It is possible that the inline filter was plugged (not sure what with). I always keep a spare set of filters on hand because they seem to get plugged pretty frequently (the only other machine I have ever had problems with was the A300-another Bobcat). I began to suspect a fuel supply blockage because I was experiencing a fuel starvation episode, and had replaced the filters. It did not fix the problem so I decided to blow back to the tank through the fuel line. This fixed the problem and it lasted for a couple of months. This leads us to the current situation. I would imagine that the filter could have been blocked. It was only in the machine for about a week though.
only other thing that may be happening is the fuel cap vent could be plugged up. it happens more often with large frame skid steers than excavators. i've watched fuel truck drivers, take off a fuel cap, set it down on a muddy track, or tire, or even drop them on the ground, then fill the tank to the top of the filler neck, and put the cap back on without even attempting to knock off the dirt inside the cap. couple days of that, and the filters are plugged :drinkup
I have had this very same problem with our Early model 435. I went through the same process as you...even when to the extent of fitting another fuel pump....still had (what i suspected) as a fuel starvation issue. However....Behind the bracket that houses the Primary, inline and Fuel pump is the inline hydraulic filter that is connected to the tank.. I replaced this filter (which is the same filter as the fan filter) after still having inconsistent fuel issues and haven't had an issue since. 5100Hours of solid work and she's still going strong.
So, just to clarify....you are saying that the replacement of the case drain hydraulic filter fixed your fuel starvation issue? That makes me wonder if maybe you changed the alignment of the fuel supply line, when you were messing around behind the filter bracket, that maybe eliminated a possible kink in said line. Otherwise I don't really see a connection to, what you did and, the fuel starvation issue. I have wondered if a kink in that line may be what is happening. Chief, a new fuel cap is an inexpensive remedy so maybe I'll try that. If that was the problem though, I would imagine that you would hear a pretty good vaccume release when you openned the fuel cap to fill. I have not heard this and I have not had any employees commment that they had either. I will ask specifically though. Thanks for the suggestions guys.
I had this exact same problem on a 435 last spring. Just about traded the machine off, We could not find the problem and spent hours and hours on it. We took the whole fuel system apart and blew it out, switched all fuel filters. Pressure checked the lift pump back by the bracket that swings out. Nothing could help us. Finally it went away on it's own.
Could be a partially stuck shut off valve that's only letting half the fuel through? Could also be the stroke limiting valve on the pump which determines how much load the swash plate puts on the pump....dragging the motor down.
Thanks again for the replies guys. I hope that I don't have a fuel shutoff issue. I guess we will see if the issue surfaces again. It has been running fine since I put it back together, No issues all week. I do not think it has anything to do with the pump stroking or de-stroking. Most times, when experiencing an episode, the machine will respond when you center the controls. What I mean is that it will regain RPMs when you stop asking the machine to do something. After a while it will only run at idle. At some point it will kill the engine. IME it "feels" like a fuel issue to me.
I have had the machine back in action for a couple of weeks now. Though I have yet to replace the fuel pump, I am not experiencing any of the problems mentioned above. I guess, like CD's, the problem has just gone away. This kind of leads me to thinking that the fuel line routing may be the key. As anyone who has ever changed the fuel filters of a 435 knows, they are on a bracket that must be removed to access the inline filter, or the pump (both of which are located on the back of said bracket-the one that holds the cartridge type fuel filter). There is enough slack in the fuel line to allow the removal of the bracket and I wonder if one should pay more attention to the routing of the line when one puts the bracket back in place.
I have a 2006 year model 435 excavator fast track machine with 3000 hrs. and have been having intermediate fuel starvation problem that comes and goes. Recently had two hydraulic cylinders rebuilt and when I put the machine back to work it stalled out and now no crank, engine turns over but does not catch. Changed all fuel filters, checked delivery and return lines and bench checked the electric fuel pump and pump ran fine. Checked for blown fuses and pump relay solenoid. Everything checked out . Put everything back together and when the keyless entry is on I have no power the fuel pump. Pulled fuel shutoff solenoid off front of diesel pump and bench checked the solenoid. This solenoid has one three wire lead and a two wire lead off the solenoid. When bench checked it would not click in and stay retracted but was a constant clicking in and out with the plunger. Is this solenoid bad? Does this solenoid cut power off to the electric fuel pump also?
the fuel shutoff solenoid has 2 coils. 1 pulls the plunger, pull coil (gets it power from the fuse/relay) as the plunger pulls back it "holds" for 5 seconds or so, then releases. during that 5 seconds the hold coil gets its signal from the controller (dash) that all parameters have been met and allows the coil to stay engaged and the engine starts. with the keyless panel on and unlocked you should get power to the electric pump. you may have a plugged fuel line down in the tank not letting the electric pump to pull fuel.