brambleberry
Active member
- Joined
- Sep 2, 2020
- Messages
- 25
I've had my '91 743ds at a local mechanic the last few months to work on a number of issues that I've never been able to figure out. He has taken care of a number of things, but has not been able to figure out a fuel supply issue that makes it incredibly hard to start the engine. Thought that someone here might have an idea or two of what's going on so we can move forward to fixing it. I've been really missing having it around the farm to move materials! It's got the Kubota 4 cyl diesel.
Ever since I bought it a few years ago, it has taken a long time of cranking to finally catch and run. Loads of black smoke, a few catches here and there but especially if it's cold, I end up having to use a jump pack to keep cranking. I also worry about burning up the starter motor, it was the only thing new that the guy had put on it when I bought the machine
Once it catches, it runs very strong and totally clear exhaust. I've used it for hours and had no problems. There is a lot of blowby that you can see hissing out the drain tube coming off the head, always oily residue there under that tube. But since the machine has had no problems with power, I assume the compression is still good enough that I don't need to dig into rings, cylinders or pistons.
I assumed that the problem was a number of small leaks in the fuel supply line, letting air bubbles creep in as it sat, and then having to push those through during the cranking. There is a good priming bulb, and the little brass knob that opens to let fuel cycle past the injectors works. The mechanic found a few cracks and pinches in the fuel hose coming out of the tank, and fixed those along with seeps in the fittings of the lines to the injector pump. The other day when I went to pick up the machine, it was pretty chilly and we could not for the life uf us get it to start. Lots of black smoke, so fuel (or was that crankcase oil???) was getting into the engine. We put in a little in-line filter to be able to see that there's airless fuel going to the lift pump etc, he had the battery hooked up to a big engine start charger, even used some starting fluid, but nothing at at all, not even any catches. Since then, we've just kept it parked and I've been meaning to ask on this forum to figure out a path forward.
The mechanic's best guess is that the injector pump is very worn, which is throwing the timing off just enough to make it hard to start. Lower cranking rpms, slightly off timing would really make problems, but once it catches and rpms increase a lot, maybe the timing being off doesn't show up much at all. So the next step there would be pulling the pump and taking it to a local place in Seymour IN that rebuilds diesel injection pumps. Or maybe trying to find a good used pump somewhere.
But I'm not quite ready to go down that road yet until I hear a bunch of other people's thoughts on this. Maybe it's a larger problem, and not worth putting any more money into? Maybe a smaller problem, and we're just missing something?
Any help is much appreciated!
TIA
Ever since I bought it a few years ago, it has taken a long time of cranking to finally catch and run. Loads of black smoke, a few catches here and there but especially if it's cold, I end up having to use a jump pack to keep cranking. I also worry about burning up the starter motor, it was the only thing new that the guy had put on it when I bought the machine
Once it catches, it runs very strong and totally clear exhaust. I've used it for hours and had no problems. There is a lot of blowby that you can see hissing out the drain tube coming off the head, always oily residue there under that tube. But since the machine has had no problems with power, I assume the compression is still good enough that I don't need to dig into rings, cylinders or pistons.
I assumed that the problem was a number of small leaks in the fuel supply line, letting air bubbles creep in as it sat, and then having to push those through during the cranking. There is a good priming bulb, and the little brass knob that opens to let fuel cycle past the injectors works. The mechanic found a few cracks and pinches in the fuel hose coming out of the tank, and fixed those along with seeps in the fittings of the lines to the injector pump. The other day when I went to pick up the machine, it was pretty chilly and we could not for the life uf us get it to start. Lots of black smoke, so fuel (or was that crankcase oil???) was getting into the engine. We put in a little in-line filter to be able to see that there's airless fuel going to the lift pump etc, he had the battery hooked up to a big engine start charger, even used some starting fluid, but nothing at at all, not even any catches. Since then, we've just kept it parked and I've been meaning to ask on this forum to figure out a path forward.
The mechanic's best guess is that the injector pump is very worn, which is throwing the timing off just enough to make it hard to start. Lower cranking rpms, slightly off timing would really make problems, but once it catches and rpms increase a lot, maybe the timing being off doesn't show up much at all. So the next step there would be pulling the pump and taking it to a local place in Seymour IN that rebuilds diesel injection pumps. Or maybe trying to find a good used pump somewhere.
But I'm not quite ready to go down that road yet until I hear a bunch of other people's thoughts on this. Maybe it's a larger problem, and not worth putting any more money into? Maybe a smaller problem, and we're just missing something?
Any help is much appreciated!
TIA
