I have a 1987 F250 6.9 IDI and having a problem with it! It will sit and idle but when a get about a 1/2 mile down the road it dies and takes a couple cranks to get it started again. Some people are saying its the Lift Pump, but I wanted to get some more info before replacing it.

 

sounds like it unless you have a clogged filter, air intrusion, or debris in the tank being sucked up.
we had a problem in my dads truck where it would run fine for a while but it would suck some junk up when he got into the throttle.

 

first thing is the filter.

you can test the lift pump by holding open the little schrader valve on the filter head while cranking, should produce 1/3 pint per 10 seconds of cranking. if it does and it isn't leaking, then your pump is good.

if your truck has dual tanks, does it happen equally on both tanks? if yes, then the problem is forward of the selector valve. if not, then it could be a problem with the pickup inside the tank.

also look for sections of rubber hose that might be getting old and soft enough to cause problems. in stock form i believe the only rubber in the fuel supply is the piece that connects to the lift pump, but check the whole line for any damage or anything weird

 

Has PO put any additional fillters under truck??remove shrader valve at fillter head, put presure gauge.4-8psi...and what they said...fuel above 1/4 tank??good luck