Thought back to "what did I do before it got worse" and realized I might have a bad gasket on the fuel pre-filter (changed the ones on the fuel filters previously). Changed the gasket, blewout all the openings on the filter head, and it seemed to run fine. Took it out for a test run and shortly after I cranked it up to 2600 things headed south quick.
Nursed it back to the garage, re-primed, still ran rough. Okay, what about the air supply? Changed air filter and traced to intake. Found engine bellows was collapsing (MB 406 987 54/91 43). Didn't have a new one on hand, so I tightened some zip-ties around it to hold it open.
Re-primed and restarted, still ran rough. Repeated and after a few initial spurts ran smoothly. Ran at increasingly higher RPMs with no issues. Thinking problem is solved, at least to the extent that the Mog runs while I await new parts. Appears to have been a collection of issues making my day challenging. THANKS TO EVERYONE FOR THE GUIDANCE.
Running into same problemsa as MogMountain. Have tried every one of his fixes but mine is acting somewhat different. I have reprimed all the way to filters several times after checking the other items and it will start everytime but I can not keep it running. It acts just like it runs out of fuel but after I open the bleeders and prime I have full fuel, no air?????????????? I hit the primer a few times and push some fuel to the pump and walla, starts, runs rough and then dies. HELP!!!!!!!!!!!!!!! I wanted to test the new "mog attachment" today. I guess tomorrow is another day.
MUD
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways - Beer in one hand - Blonde in the other - body thoroughly used up, totally worn out and screaming Wooooo Hooooo what a ride".
Check to see if there may be something blocking the fuel flow from the tank. Just pulled a rag from the tank of my dozer that had been restricting fuel flow - would start but die as soon as I gave it any throttle. If tank is full I'd pull the pre-filter and blow some air through the line.
Also, does your tank have a fuel strainer in it? Might check it as well. Relative to my earlier comment about paint flakes, I used a spare 406 tank the other day and found paint flakes in it as well. Doesn't make sense that it would be a factory issue, but two tanks with paint flakes is worth mentioning.
Checked venting and also for something in the tank. I saw a post somewhere that mentioned a "new" style of primer pump. Does that mean there is a known problem in the primer? New fuel filters coming in today will open them again and try, Maybe after I religned the tank something plugged filters finally?????? We will check tonight.
MUD
Checked venting and also for something in the tank. I saw a post somewhere that mentioned a "new" style of primer pump. Does that mean there is a known problem in the primer? ..
Yes the old style primer was prone to develop leaks with age.
Try using air pressure to blow all your lines out to help clear any potential crud in the lines. Obviously this means you will have to reprime the whole system which will help you notice if you have a problem with your primer pump. It wont give you a good pump if its leaking air. I have heard though its a long pumping time to reprime from empty lines. You might try a Mighty Vac to help. No clue if mighty vac is stronger than a good primer pump or not.
It runs again!!!!!!!!!!!!!!!!!!!!!! Changed fuel filters again and when I put the new gaskets in I found an old piece that was stuck in the rim of the 2nd filter. I'm guessing thats where the air was coming from, just not a good seal on that little spot. I reprimed after the install and the old girl popped right off. A few minutes of gurgling but it never died and then went for a drive around the farm. Positive note_ Getting better acquainted with the systems on the mog_ right!!!!!!
Thanks for all the input,
MUD
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