I have a 850G with the 12v Cummins (3500hrs on meter) and have a few questions. The last few times I've ran the dozer the engine will stumble like it's running out of fuel. This only happens after pushing heavy brush and letting of the accelerator to go into reverse and it might only happen 2-3 times during a 6-8 hour day. The fuel filters only have 100 hours on them and the tank looks clean so I'm kinda leaning towards a fuel pressure issue. I know the pressure should be 5-7 psi under full load but I'm not sure where to check it. Also wondering if the Primer Pump is the fuel pump for these engines or only used to bleed the air out of system. I have read through the service manual but there is not anything I can find on checking fuel pressure. Also wondering if anyone knows how to do a quick blowby test to check engine wear, other than the manometer test method. Thanks
Hows it going with this? The primer pump is the fuel pump, but the injection pump is also. A good blow by test is to sit the oil fill cap on the filler neck area, if it blows off this means the blow by is excessive.
After I wrote the post I cleaned the air filter and it was really dirty. It surprised me how dirty it was because we had been working in really muddy conditions. After this I hired a guy to run the dozer for me and he claims it never stalls on him. He runs it and I service it every 20 hours or so. We've been doing this for about 300 hours now. I did get a fuel pump but never put it on. I plan on doing a blowby test this winter. I tried the filler cap test but the cap is a big rubber plug, I don't think it would blow it off. Engine does burn 2 quarts every 75 hrs. I think it might be the turbo but haven't pulled the elbow to look.
2 quarts is pretty minimal as far as I'm concerned. I'm around a Case 850H , it was losing power and we found a screen on the fuel inlet to the injection pump was plugged. These are good dozers.
I may try to replace the pump this weekend. I'll also look for a screen in the line (hadn't thought of that). The other thing I noticed is the dozer doesn't black smoke under heavy load. Some say this is a good sign some say it should black smoke. Any opinions on black smoke? I bought the dozer to clear a couple hundred acres and then sell it but now that we are done clearing think I may keep it. As **** jr says it seems like a good dozer and I really like running it.
Lack of black smoke means you're not getting too much fuel, or not getting enough depending on your political persuasion I'd be looking for any screens, either in the tank, or at the transfer pump inlet, or inside a banjo bolt if it was Japanese, or a plugged up fitting. If you can put a tee into the fuel line just before the injection pump, then you can run a line to the cab and use a vacuum pressure gauge to see what it does when you use it full load and if it stalls. But the fuel pump is probably cheap enough to change it while you're looking at the other fittings, and see what it does.
Replaced the fuel pump today and looked for a screen that could be plugged. Pump replacement went fairly quick and I'm pretty sure old pump was the original. Didn't find any kind of screen but did notice a small leak where throttle goes into injection pump. Wasn't able to run dozer but it pretty much sounded and revved up the same. I also put 3 quarts of Lucas in the oil since I was changing it. I'm not a believer in this sort of stuff but enough people told me to do it so figured what the heck. We'll see how things go.