Our link belt excavator is having major fuel issues. It will run great for a bit, then it will bog down and sometimes die, sometimes it will come back and run normal. We have replaced the line between the tank and fuel pump and didn't help. We even put in an electric lift pump and that didn't seem to help. We have replaced fuel filters more times than I can count and drained the water out of the tank. Neither seem to help. There are no noticeable fuel leaks where air might be coming in. What are the symptoms of a bad injection pump? What about failing injectors? When it dies you can pump the primer pump and it fires right up.
Engine? year? injection pump model? None of those sound like injection pump issues to me, but that's a wild guess not knowing if it's a rotary pump or common rail. One way to diagnose a possible fuel pressure problem is to use a fuel pressure gauge before the injection pump. The Japanese engines liked to put a filter in the banjo bolt intake to the transfer pump.
What engine? If it's Japanese (sumitomo link-belt?) look for banjo bolts in the fuel system, remove them all one at a time and look for a tiny screen in the center of the hollow bolts. Also could be sucking air at the priming pump or the transfer pump though with an electric pump it should not suck air because of the head on the inlet line.
You have probably checked this but I will throw it out there anyway... Did you check and make sure your vent on the fuel tank is not plugged? We have a cat 920 loader that had the same symptoms a few months ago and that ended up being the problem.
Check inside the fuel tank for a floating whatever that maybe periodically obstructing the fuel draw.
That sounds to me like the classic symptoms of either pulling air into the system or an obstruction in a fuel line or fitting somewhere.
screen in one of the banjo bolts.
Banjo bolt screens as said in above post but i would also be draining the tank to see if you have a floating piece of plastic bag as these once the engine has stopped often fall away from pick up pipe and allow you to bleed the system without issue and run again until you start supping some juice and the cycle starts again .
Thank you for the ideas guys. I will try to do some troubleshooting and report back.
The older Stink Belts has a suction strainer mounted on the fuel tank next to the swing machinery. The canister had an O ring that would fall out. People would put the canister back on without knowing the O ring was gone and they would then have exactly the problems you are describing.
Thank you for the input everyone. I finally had a few minutes to work on the machine. Now when I pump the primer pump and start the machine it will only run for about 30-45 sec before it dies. Looks like the o-ring is in tact. I left the fuel cap off while I ran the machine and it still died. I pulled a bunch of the banjo bolts but couldn't find a screen. Here is a picture of the fuel system, maybe someone can point me toward the bolt most likely to have the screen.
The bottom of the primer pump is the inlet, right? biggest line from the tank to the water separator and then to the priming pump, then out the bolt on the top up to the filter, then back to the injection pump. The bolt on the bottom is the one that will have the screen. Is there a plastic bowl water separator on this? and have you cleaned it? mostly to see how bad it is, it would be tough to plug one of those up, but if it's missing something or wasn't put back together right, then the junk would go on up the line...
Yup.. the bolt under the hand primer is the screen bolt or should be anyway.. I've seen them in filter heads also.. The big nut on the return line above the HP, is an overflow valve.. its supposed to hold gallery pressure to keep a constant supply of fuel for the pumping plungers.. IF the spring in the ovflo valve is broken.. it wont hold fuel and it will run for a few and die out.. until you pump the pressure back up w/ the hp. Just something else to check..
I pulled the big nut under the primer pump and it just had a spring and metal plunger. I will check the pressure relief spring too.
No, they were talking about the banjo bolt under the primer pump, where the suction line from the tank attaches. If it has a screen in a banjo bolt, that's usually where it is, to keep particles out of the transfer pump check valves.
fuel problem Hi guys i m from Russia newbie here excuse me for my bad English.I think problem is in fuel assambly.Try to pass it by take clean fuel or fuel flush and connect the line straight to a fuel pump.I hope u got me right. Glad to be any help.
I was mistaken.i mean fuel filter assambly.