Ok folks needing help.
culprit 1992 f350 4x4 idi, banks turbo, hypermax intercooler, 5 spd zf. dually
this truck has been very faithful starting always even in single digit weather without plugging in heater.
I keep good maintenance on her, lately its been getting hard to start after sitting a day or longer. needing to crank it for extended period to fire up.
then she is good all day. automatically i thought its was time for service on the fuel return lines. so i installed new lines and o-rings, filter etc...
i did not do olives on lift pump line in.
heres the funny thing. if i shut it off on a full tank front or rear it will fire up after days of sitting but if the tank below 1/2 full its a bear. so for now i keep rear tank full and use out front tank and switch just before getting home. i have had these old trucks for years and know im overlooking something easy.
any ideas are apprecitated. p.s lift pump was new 30k ago.
perhaps i should just switch to electric pump as others have done.

 

update: i kept the truck on rear tank that was full and she sat for 2 days and i fired her right up this morning. once on the road i switched back to front tank. that tank has just under 1/4 tank showing about 10 miles up the road i noticed the engine sort of missing so i switched back to the rear tank and finished my trip without incident. i half believe i must be drawing air at possibly the fsv. my thinking is possibly drawing harder on less fuel in the tank she might be pulling some air. no issues when this tank is full. hmm i think im just gonna start tightening and installing new fuel lines under there.

 

1/4 tank? Probably the pickup is cracked or broken off inside the tank. Common problem at this age.