Post your questions or problems you are haviing with your Yanmar tractor here.
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Hi there, I have an AF30 Yanmar which has been a great workhorse for some time now. Documentation for it seems rather scarce and the problem I'm experiencing is somewhat frustrating: the tractor has a tendency for stalling 'episodes'... that is, not consistently. IF it happens, this ONLY takes place when travelling uphill (forwards). This problem does not occur travelling uphill backwards(!). As soon as a level location is again reached and a few minutes pass, the stalling no longer occurs and everything seems normal again. My suspicion is that it's fuel-related, however, looking at the fuel lines, can it be that this tractor has 2 tanks (under the foot plate, one on each side). I assume that the only possibility is some sort of foreign matter periodically clogging the fuel intake line... at other times it might be happily swimming around the tank(s). Tried running without fuel cap (vacuum lock check) but no noticeable difference. It sounds like a fuel pump is chugging away happily at all times as well (as tank below engine on this model). Any suggestions, please? Maintenance has been regular (fuel filter, air filter, oil etc.). Carefully warming it up prior to use etc. Occurs with/without loads, soon after starting out or towards end of working session.
I'm not going to be much help on that one. I don't even have a parts book on any of the AF models. I agree that it sounds fuel related. It could also be electrical though if you have an electric fuel pump and electric shutoff. It might be something like a wire with a bad spot that loses connection at a certain position. Troubleshooting those intermittent problems is tough.
From what I have found the AF series Yanmars were a joint project between Yanmar and Shibaura which might explain why they are so much different than the other 'F' series.
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it's almest definitely a fuel related problem, but if you seriously do not know how many fuel tanks you have or their location I don't see much hope for troubleshooting.
I googled the AF series to see what it was and came across a major supplier in Osaka -- that might be able to help.
Case closed! Thank you everyone for the suggestions and tips. Both tanks were removed and inspected. While a quick visual did not have anything significant (just a few small deposits), we thought that maybe something might be 'lurking in the shadows' as all electrical connections were in good shape. Taking some thinner as a cleaner/flushing agent we managed to collect a frightening amount of sizeable 'nuggets' (no idea what they could be). This involved shaking the tanks quite vigorously for up to a minute, then pouring out the contents. The process was repeated some 5-6 times on each tank until no new solid matter appeared in the residue. Also, a metal thimble-like fuel strainer (where the fuel from the tanks joined the fuel line) had a generous coating of sludge on it. Since then... 'running like new'! An image of the mystery nuggets is attached.
- nuggets_small.jpg (86.97 KiB) Viewed 241 times
Thanks for the update. Always interesting and helpful to others when a problem is solved.
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