I'm working on a 86 f150 with a 302 in it will start an run for a few sec then just stops running then when I try to restart it seams like the battery is low or something in the motor is really tight but it will restart after a bit just fine

 

Bad alternator or battery? Have you tried cranking it with jumper cables to see if it at least turns over faster? A bad alternator will, A), make your battery have a low charge or be dead, obviously, and B) won't power the computer well enough to make it run properly. How many miles are on the engine? Curious when, or if, it's had the timing chain/gears replaced.

 

I have done timing chane, altanater, battery, fuel pump and I have come to the conclusion that I need to replace the starteran the control model or just get rid of the truck.

 

There's a lot of Ford Guru's on this site, I'm sure you will have some responses from more knowledgeable people than myself. Sounds like it could be two separate issues, one causing hard starts, and the other causing a bad idle or running condition. That's if you don't have a spun bearing or something. It can be very hard to diagnose issues online at times. Not to mention, the chance of getting a new part that is bad from the start. Did you replace the timing chain, alternator, battery, and fuel pump to try and remedy this problem, or have those been replaced and it ran good for a while? I'm not questioning your work, just mainly curious if when the timing job was done, if it ran better, was before this problem, or already had the problem and made no difference. What I'm wondering is if it is in time correctly. Again, no insult meant at all towards the work done.

Oh, also, if you still have the original set up (5.0 EFI/SD computer), maybe you could pull the codes on it. It's worth a shot. Not sure if it's had the battery hooked up long enough along with ran long enough to create a code and keep it in memory.

 

YOU have replaced? or you have paid someone to replace?

You are not telling us many many things. Probably because diagnostics 101 has not been done.

a. battery voltage when running
b. have all vacuum leaks been checked?
c. whats vacuum pressure?
d. what is fuel pressure?
e. battery voltage when cranking?
f. next time it dies, spray starter fluid in the throttle bore, and restart, does it restart faster?
e. run the engine at 2000 - 3000 rpm from the start, does the engine still die?

from the almost nothing you told us, i guess there is a massive vacuum leak, and when the choke is on it runs good, when the choke is open it dies suddenly, after a few recranks it finally gets enough fuel to run without choke

air + fuel + spark + compression = running engine
vacuum leaks = NO RUNNING ENGINE

 

Well the truck was given to me because the timing chain was bad so I repaired it and all the other stuff and it ran fine with no belts on it when it was test ran then everything was put back on it and it's burnt up two starters and everyone I have talked to about it has said the control mogul is bad because the timing is right on the money

 

I'm sorry so you and everyone else knows I have been working on and fixing car's and trucks now for 20 years so on that note yes I have done all of that with no avail so if I keep on the gas it will run but as soon as I let off of it it stops running I have put two different deep cycle RV batteries in the truck with the same out come besides the dumb thing is not throwing any codes or anything

 

Great then it should be a simple thing to fix..

a. battery voltage when running?

c. whats vacuum pressure?
d. what is fuel pressure?
e. battery voltage when cranking?

or the idle circuit is clogged / brake booster leak.. from what you tell us the idle mixture is off somehow