Hi all. I have a 772g that two days ago it started acting like the filters were plugged. Be in the middle of grading and fall on its face but would recover. I replaced the filters and it fired right up no problem and ran for 5 minutes to move it. Next morning fires right up, move like 5 feet and it dies. Now when I fire it up it idles at 300 rpm. No functions of any kind. Won’t throttle up. Just sits there at 290-310 rpm. No codes. No restrictions. Nothing abnormal. Just fires up and barely runs.
Will need the machine's full serial number. Did you scroll through the monitor and check for DTCs, or were you just waiting for a DTC light to appear?
Dw772gx627437 It’s not showing any codes. Other than low voltage when it’s idling at 300 but monitor shows 23.8v so I’m assuming that’s a fault because the alternator isn’t performing. So a little more info I forgot about. The day before the 300rpm issue, it fell on its face twice while working. Dripping to 8 or 900 rpm but I could neutral it and it would recover. Acted like fuel filters. A code popped up that said fuel system failure… but it never stored and went away after it flashed once. I also had a turbo over temp code flash twice and they never stored and an inching pedal above neutral code. Symptoms made me believe filters so I swapped in new. Fired back up and that’s when it died and upon restart I’m stuck in this 300rpm idle. It’s almost like limp mode, no throttle response on engine, no control of anything really. But I can’t get a code to throw, plenty of fuel pressure being provided by lift pump I know my voltage regulator is going out and have a new one on order. Could that have anything to do with it
It is always good to insure the electrical system is sound. Stray charging system voltages or excessive AC voltages in the charging system can play havoc with electronics. Usually that message about a fuel system failure means that there is a mismatch between the desired rail pressure and the actual rail pressure, which could be caused by a poorly performing supply system. Usually that message will generate a DTC. Has fuel pressure been physically checked with a gauge? You could also try a separate fuel supply to eliminate any issues with the suction side of the fuel system. Are any of the function levers stuck in the engaged position? Does it start hard, or start right up? You want to make sure there is no unwanted load on the engine. Other than some basic steps as above, you will most likely need someone with diagnostic software to plug in and see what may be going on.
OK, so here’s an update. I was able to get the codes to pop up. There was something to do with the low RPMs, not allowing the codes to show up. I gave the machine a couple shots of ether and that increase the rpm’s. Which the wierd part was once I got the rpm’s up they would stay there. Shut the machine off and restart and they’d stay up there. Never went back down to 300. Super odd. Additionally once the Rpm’s hit 850 I got a Handfull of codes. 1347.7 fuel system failure 1180.0 high turbo inlet temp 1569.31 derate I swapped out the lift pump I believe the old one was weak. I now have full 2200 rpm and codes went away for the most part. Occasionally I’m getting high turbo inlet temp, but it comes when I put the machine under load and the rpm’s drag down to 1100 and black smoke present. I take the load off and I can throttle 2200 and temp code goes away and smoke as well
‘excessive AC voltages in the charging system can play havoc with electronics.’ Had this happen with rebuilt alternators. Idle speed fluctuates so bad cold engine stalled as it warmed up the fluctuations reduced and almost went away. .5 - 1 volt ac voltage from three rebuilt. New Bosch solved that problem. 2000 Toyota v6