the furnace runs fine with intake only part way on intake of furnace. However it goes out when fully installed. The pipe seems to be clear of any blockages? Is pipe too small 2" PVC? Too long with too many elbows 2-3 elbows roughly 25' long. Or it OK to just run it pulling part air from basement (which I've done for years)? But recent inspections trying to sell my home the inspector questioned it??
Review the manufacturer's specifications, these should be in a booklet attached to the boiler jacket, if not, go online and you can likely find the specs. The manufacturer's specs will specify maximum length of run and what changes of direction you can have and how it will shorten the allowable run.
there is something like an 8" duct typically recommended for a "typical" boiler. i have nothing, but my house is not super-tight; 5 ACH@50 ("tight" is approx "below 2"). in my son's house (tighter) we have a 3" abs pipe near the ceiling in his boiler room, and he is doing fine. as said above, see what the manufacturer recommends. a big problem can be back-drafting through other appliances, so fresh air available is always a good idea.