Avant 420 loader cold start problem

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belgian

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Because of my bad back, I got myself a helping hand for handling the heavy stuff around the house a few years ago
It's a low hours (300h, as new) Avant 420 which has a Kubota D722 diesel engine.

It is only used a few times a year, so doesn't run much. The last 2 times I used it, I had trouble cold starting the engine. It cranks well (good battery, fully loaded), coughs a few times but does not start, even when glowing longer than the glowing lamp indicates.

Once it has started (but only after several attempts), restart is instant, even the next day.

It only does so when the motor has not started for several weeks or so. I suspect a fuel delivery problem, but am not sure. Any hints are appreciated.

420T_l.JPG D722_a.JPG
 
Probably just needs a climate change. Ship it to Tennessee and I will see if I can replicate the problem over the next six months. Seriously, I don’t know but I have an old diesel pickup that does something similar so I will be paying attention here.

Ron
 
Did a little google search. Everything from air leak to too much lift pump pressure to not enough lift pressure to my favorite for your symptoms - a leaking check valve - assuming of course that your fuel system has such. I know I will be looking for this on my truck.

Ron
 
If my check valve is too hard or expensive to fix, I am going to try the above. Ron
Hi Ron,

thanks for your input. The climate change proposal is nice, but the weather here is fine as it is LOL.:laugh:
The check valve may be a solution though, and will definately look into that. My first checks will be as follows :

- Ordered some new glow plugs. will check them out shortly.
- Change fuel filter. Diesel fuel will get a bit old and maybe the previous owner faced some parafine building due to cold weather. Not sure though.
- Back -drainage may well be an issue due to small air leak somewhere in the fuel system. Hard to find maybe.

I'll dig into the problem when I have some time available in the coming weeks. So my report may take some time.
 
There is a lot of information on the web regarding similar symptoms in general. I hope you find it to be a simple fix.

I wish there were more machines like yours over here. Skidsteers are common place. Our wood lot uses three. A machine like yours would be much safer, and probably more economical and efficient for our uses. Every time I locate a reasonably priced one it seems to be on your side of the pond.

Ron
 
I know what you mean, but articulated loaders are much sought after here also. Farmers are the biggest users and run them daily to clean stables, Transport hay, etc. Good used ones still are expensive, so was mine. Skidsteers are too nervous to my liking.
 
Just out of curiosity, what fuel are you using?

I knew an elder gentleman who had bought a slightly used John Deere diesel lawn tractor and had issues very similar to yours. After basically trying everything, our attention switched to the fuel, and it was the right answer.
Turns out he was using agri (off-road) diesel fuel, which in Europe has a rather high water content. Since he hadn't much lawn to cut and basically filled the tank once or so a year, moisture tended to build up at the bottom of the tank, meaning each time he turned on the tractor after leaving it parked for a few weeks the fuel pump was mostly sucking water until it had mixed it enough with fuel. Things got worse in cooler weather as diesel fuel becomes denser and harder to mix with water.
The solution was to simply switch over to ordinary on-road diesel fuel: more expensive, but given how much fuel he used every year not a big deal.
 
Are you sure those glow plugs are working? Had a bad one on low hour Bolens 15hp tractor, made it hard starting.
 
Just out of curiosity, what fuel are you using?

.

good point. But I am using two elder Kubota lawn mower tractors with the same agro-type fuel (tax reduced red color diesel), which is used for all farming equipment around here. Never had a problem.
From what I hear, the red color agri-diesel is just the same diesel as the white color diesel road diesel over here, with some coloring red pigment, of which the chemistry is kept widely a secret for the public. But I am not sure. Nevertheless, never encountered water in the diesel over here.

Are you sure those glow plugs are working? Had a bad one on low hour Bolens 15hp tractor, made it hard starting.

Glow plugs are working fine, so that' not it.

From the local dealer, he advised me to keep the fuel pump running longer before starting, since this engine has an electric fuel pump. There might be a tiny leak in the pump check valve , allowing fuel to drain back to the tank after long time without use. I think he's right on the money. Will check this weekend since I have wood to split….
 
I tried the trick the dealer recommended and it indeed helped. This engine has an electric fuel pump and start pumping (ticking sound) as soon as you turn the key towards glowing. So I let the pump running for a while, then let it glow normally, and start as usual. Obviously there is a fuel drain back when the engine sits for a while. So I'll have to look into that later. But at least, I know how to bypass the problem for the moment. Thanks for the tips.
 
Just out of curiosity, what fuel are you using?

I knew an elder gentleman who had bought a slightly used John Deere diesel lawn tractor and had issues very similar to yours. After basically trying everything, our attention switched to the fuel, and it was the right answer.
Turns out he was using agri (off-road) diesel fuel, which in Europe has a rather high water content. Since he hadn't much lawn to cut and basically filled the tank once or so a year, moisture tended to build up at the bottom of the tank, meaning each time he turned on the tractor after leaving it parked for a few weeks the fuel pump was mostly sucking water until it had mixed it enough with fuel. Things got worse in cooler weather as diesel fuel becomes denser and harder to mix with water.
The solution was to simply switch over to ordinary on-road diesel fuel: more expensive, but given how much fuel he used every year not a big deal.

How could the water get through the filters on the fuel pumps?
 
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