Forum:
I have a 99 fourtrak usually very reliable, however got it out of garage today ran fine for 10 mins than engine died diesel starved. Diesel is spraying out of filter bottom ( even with ignition and engine off) only thing that stops it is opening the filler cap ( under huge suction) the engine will run for about 30 secs and cycle starts again. If I try with filler cap on engine will not run at all. Can anyone help?
Vacuum forming in the tank is
Vacuum forming in the tank is caused by a blocked breather, follow the small breather pipes from the tank and you will find it. Small canister about 50mm long, inside is a ball bearing sitting between two springs which centralise it, these generally clog or seize.
Clean thoroughly and apply copious quantities of penetrating oil inside to free it, then suck and blow to ensure it is free. Lubricate with engine oil and refit.
If it will not free then fit a small universal fuel filter to the pipe, cap the top and prick a small hole into it.
Spraying fuel from the filter bottom is most likely the fuel drain loose, or the "O" ring is deteriorated. Remove the filter and check all is tight, and the "O" ring is fitted correctly. Check the drain plug itself as these are plastic and can be overtightened, stripping the threads.
Check the filter casing, these can sometimes split if they are cheap filters, or damaged during installation.