so i have a 94 f150 with the 4.9 six. has 138000 miles one owner. i bought it from original owner who kept it maintained very well but has sat for 2 years. the other night i was driving and it stalled out and would not restart. after many attempts and switching tanks back and forth it restarted and made it home. i tried to restart and it would not. next day i changed fuel filter and same issue. it will starts but only after key on off multiple time and once running it seems fine. fuel pressures are 48spi idle and 50 running and does not go up or change even when doing fuel regualtor test. is it the fuel pumps?? seem sstarnge they both go at same time

 

Where did the vehicle sit for the 2 year period, inside or outside?

 

hard to say truck looks like it was under car port real clean truck

 

As long as it was exposed to outside moisture, humidity, you will need to check all the ground connections for cleanliness and tightness. Looking at them does nothing ,they need to be removed cleaned with sandpaper or wire brush and reinstalled.
When you say it won't restart, just what does it do ?
Cranks over , but will not run or cranks over slowly or not at all?

 

so i have drove it for 2 weeks then on saturday night it stalled i was able to get it started and get home. fuel pressures are 40psi key on and idle. i changed the furel filter, i am leaning toward being starved for fuel as it will start eventually and run fine. then it will not restart.

 

Does your truck have dual tanks?

You are just below the fuel pressure spec of 45-60.

 

yes it has 2 tanks. I just did a quick test with a spark plug light. I have ingition on both plugs and coil during turn over. the fuel pressure is 45-48. Do fuel regulator go out commonly on these trucks.

 

The regulator's purpose is to keep the pressure from going too high. If you pull the vacuum line off the regulator and fuel squirts out, it is bad. Replace it only if fuel comes out of the vacuum nipple. You are within specs as far as pressure goes.
Is your truck at a no start condition right now?

 

it started but hesitated. It cranks and cranks and then sputters to life.

 

What do the plugs look like? Are you actually getting good spark at the plugs? Weak spark will carbon foul the plugs.Seen those ignition coils go bad too.

You need fuel, spark (at the correct time) , compression and air to run. It appears you have proper fuel pressure. Does it hold when the engine is shut off? If those two things check out, I would check and record compression of all six cylinders. If there is a weak link to the 4.9, I would have to say it is the nylon teeth of the timing gear shearing. That should show up on your compression tests.

Finally, I seen this happen once on a 4.9 and it fooled a lot of people where they were tearing the engine down, thinking it was an internal issue..Same symptom as you describe, couldn't keep it running. The EGR valve had a hole burned through the pintle.