Chiliman77
New Member
Hi all- I have a 2006 Bobcat 435, S/N 563212092 and am seeing some issues with it bogging down after use (10 minutes to an hour, variable). Prior to this it will start and run normally. Once it bogs, if I back off usually it stays running as long as I’m quick enough, otherwise it stalls. After the issue begins the machine will start again normally, and have power for 10-20 seconds, then the issue repeats until the machine sits for a while (no idea how long is required, usually when this happens it means my day is done).
When it first happened I changed air and fuel filters, and water separator. Not enough water to seem significant (maybe a teaspoon) and a few flecks of crud in the filter. Last change was a few years/100 hrs ago (new machine to me recently, had been working fine). When this happens I notice no smoke coming out of the exhaust.
Based on my (very limited) diesel/ hydraulic knowledge and more experience with gas, this seems like a fuel issue. I’ve done some digging on forums and I’ve heard filters, fuel lines, fuel cap, injector return line, fuel pump. Filters replaced (and checked again), return line changed out, cap loosened with no vacuum release noise/ left loose when running to confirm. Fuel supply issues remain, but the electric pump certainly pumps, and pushes fuel. I’m not sure how to determine if this is “enough “ flow. If I could find some in line pressure gauge, what should it be? Would it be easier to just swap the pump? As far as fuel lines/supply, I was going to try to rig up an aux tank, but since it needs to be operational for such a long time, I’m struggling to find a good way to rig a tank. I also haven’t replaced the supply lines, but figured I’d get input here before I just started changing parts.
I had thought it might be related to fuel level and machine orientation when low, but I got a half tank in now and same issue. I’m finding it challenging to troubleshoot effectively when it can function for so long without a big problem. That said, it may be operating a little underpowered the whole time- I don’t have much time on the machine, but I feel like I’m throttling up more than I used to. This also could be because I’m getting more comfortable. Too many variables, not very helpful…
Troubling questions:
1. Why would it run well for such a long time and then suddenly have an issue? I’d think the problem would be more immediate if it were a fuel issue based on a bad part.
2. When I was trying to debug the discharge/return line, I put in a second line running to an empty bottle. Idling I would get a fair amount of fuel out (a cup every 5-10 minutes?) and when in use I would struggle to get a cup in an hour. That said, the other day I left it idling to warm up and had about a cup of fuel in the bottle, and after running (and having my issue appear again) I checked it and the bottle was empty. I realize that my line was running to the bottom of the bottle (I believe the tank return does not have a pickup and just dumps into the top, but am not confident). This means that at some point, the return line pulled a vacuum and drew the discharge back in. I’m not very familiar with diesel as mentioned, but this seems really odd. Also concerning since there were no filters, I hadn’t considered this was a possibility. Why would this happen? How?
Anyone have any suggestions for me? I’ve read a lot about banjo bolts and pickup screens, but from looking at my unit it seems the fuel line connections are all just hose barbs, and from the parts list it looks like the pickup tube is just a tube.
Thanks!
When it first happened I changed air and fuel filters, and water separator. Not enough water to seem significant (maybe a teaspoon) and a few flecks of crud in the filter. Last change was a few years/100 hrs ago (new machine to me recently, had been working fine). When this happens I notice no smoke coming out of the exhaust.
Based on my (very limited) diesel/ hydraulic knowledge and more experience with gas, this seems like a fuel issue. I’ve done some digging on forums and I’ve heard filters, fuel lines, fuel cap, injector return line, fuel pump. Filters replaced (and checked again), return line changed out, cap loosened with no vacuum release noise/ left loose when running to confirm. Fuel supply issues remain, but the electric pump certainly pumps, and pushes fuel. I’m not sure how to determine if this is “enough “ flow. If I could find some in line pressure gauge, what should it be? Would it be easier to just swap the pump? As far as fuel lines/supply, I was going to try to rig up an aux tank, but since it needs to be operational for such a long time, I’m struggling to find a good way to rig a tank. I also haven’t replaced the supply lines, but figured I’d get input here before I just started changing parts.
I had thought it might be related to fuel level and machine orientation when low, but I got a half tank in now and same issue. I’m finding it challenging to troubleshoot effectively when it can function for so long without a big problem. That said, it may be operating a little underpowered the whole time- I don’t have much time on the machine, but I feel like I’m throttling up more than I used to. This also could be because I’m getting more comfortable. Too many variables, not very helpful…
Troubling questions:
1. Why would it run well for such a long time and then suddenly have an issue? I’d think the problem would be more immediate if it were a fuel issue based on a bad part.
2. When I was trying to debug the discharge/return line, I put in a second line running to an empty bottle. Idling I would get a fair amount of fuel out (a cup every 5-10 minutes?) and when in use I would struggle to get a cup in an hour. That said, the other day I left it idling to warm up and had about a cup of fuel in the bottle, and after running (and having my issue appear again) I checked it and the bottle was empty. I realize that my line was running to the bottom of the bottle (I believe the tank return does not have a pickup and just dumps into the top, but am not confident). This means that at some point, the return line pulled a vacuum and drew the discharge back in. I’m not very familiar with diesel as mentioned, but this seems really odd. Also concerning since there were no filters, I hadn’t considered this was a possibility. Why would this happen? How?
Anyone have any suggestions for me? I’ve read a lot about banjo bolts and pickup screens, but from looking at my unit it seems the fuel line connections are all just hose barbs, and from the parts list it looks like the pickup tube is just a tube.
Thanks!
ive seen the exact problem you described many many times when the 430/435's were still in production