Hello I am new to the forum and it seems like there are a lot of very knowledgeable people here. Hoping one of you could help me out. I have a 2004 Bobcat 773G Skidsteer. Since we bought it used with 2200 hours it has had a cold start issue. We replaced all the glow plugs and relay and that did not help. The issue is when we go out to start it for the first time that day, after the countdown, when you try to start it just keeps rolling over with whitish/Gray smoke coming out. After 3-4 tried it will start but sometimes it burns the battery dead before it starts so then we have to charge the battery. After it is started once you can immediately turn it off and it will start right up again and it starts great the rest of the day. Anyone have any ideas what this could be. Any help would be greatly appreciated. Thank you
It sounds like your glow plugs aren't working. I'd check to see that they're getting voltage, run a test lead to a glow plug connection and into a voltmeter where you can see it, then confirm that there's voltage present during the countdown. If there is 12V, then double check the resistance of your glow plugs individually, take the electrical connector off and measure resistance to ground, you'll need a decent meter to measure the ohms accurately, a $3 HF meter won't do much. They should all have the same resistance. If you don't have a good meter, then you can still check if they're burned out with any cheap meter.
I actually pulled all the new glow plugs and they tested good. The glow plugs are also getting power. It had a bad relay in may and I replaced that then but it didn't help. I was told it could be a "drain back" issue but I am not sure where to start with that.
OK, that makes perfect sense too. No power to the glow plugs would usually be white smoke I guess. I can't help with a bobcat, but I fixed the same drainback issue on a different diesel by putting the tank above the engine... Basically you're getting air leaking into the fuel supply somewhere, filters, rubber hoses, check valves,lift pump, they're all suspect.
Check to make sure the little thumb wheel (on return lines) at the injection pump is closed. Also check the washer under the fuel filter bleed screw. Kubota V2203 uses pre-combustion chambers so a lack of fuel will make starting very difficult. White/Grey smoke means it is getting some fuel. Can't rule out leaking injectors, timing (least likely) or compression issues.
Spike>> "drain back" is when the fuel "drains back" to the fuel tank when u shut it off for the nite.. Normally happens at the lift/supply pump.. the valves get old, weak or something get in them{trash}.. & once u keep cranking on it.. the fuel eventually gets to the inj. pump & the engine starts.. It'll start good all day & then when u shut'r down for the nite.. the fuel creeps back, past the valves.. NOW, some engines don't have a supply/lift pump & experience the same symptoms.. in that case, its the overflow valve that keeps the pressure in the system, along w/ copper gaskets & things like that. Its not uncommon for this to happen.. but its a PITA to find sometimes.. start at the lift pump if it has 1.. & replace it. They're less than 50.00
A simple test I often do is to put a air blower into the fuel tank spout with a rag to seal some of the pressure but not over pressurize it. Have someone else put the 1-2 PSI in the tank while you check the fuel lines and fuel system for new leaks. Tends to leak where it is sucking air. Simon
It is also a good way to help start an engine that has run out of fuel and has refilled filters but has air in the system. I've done this while bleeding pumps also or when bleeding Banjo Fittings to get the air out. Simon
Bobcat machines have a primer bulb. If you suspect a faulty lift pump on a Bobcat, simple. Before start up, open the bleed screw on the injection pump return line and operate the primer bulb for enough pumps to insure fuel is delivered to the injection pump. Then close the bleed valve and pump the primer bulb until it's firm, then see if the engine fires off after glow plug countdown
Good point Willie59. I was just saying that the technique works reasonably well on many engines, but if this system has a primer your way would be better. Airing lightly does help to find suction leaks. Simon
No doubt. And the primer doesn't matter if the fuel lines do have other issues causing air ingress. Just saying, with a Bobcat, start checking it out with the primer bulb. If it doesn't work out, then carry on to other sources of the problem
You know??!! I forgot about the "primer bulb" THEY are 1 way check valves.. If IT'S leaking down...?? Same thing.. Bleed back..
if you have fuel bleeding back to the tank, you may want to pull the suction hose out of the tank, check it for cracks and make sure the screen/check valve is there
Yep, there's a check valve there as well.