Seems that I have solved the fuel problem this morning. Tank and fuel line to water separator seemd to be OK, but some trash have been accumulated at the tank shut off valve located before water separator. This seemd to be the problem. After cleaning the shut off valve problem dissappeared. After thinking about this when working in the combine today, this valve could be only place for trash to accumulate, because fuel did not went through any filter yet, and design of valve does not permit bigger particles to go through it. Seems to me that my 1660 deos not have anything in the tank (screens, etc.),or this is factory built in. FYI My combine does have three fuel filters (one water separator on lH side at the rear of machine and two filters coarse and fine one located in engine compartment). Anyway thanks for reading my message.