TN90 having trouble keeping it running

[downslope]

I don't know how fuel hoses are routed from the tank onwards, but check to be sure a hose didn't get pinched somewhere along the way. I have seen this happen on a TD series and the symptoms were similar to yours.

 

[RickB]

Sorry, I read TN90 and thought TL90. Check the banjo fitting on the inlet side of the mechanical transfer pump. You don't have a water separator filter.