Hard cold start
Thread Starter
Junior Member
Joined: Feb 2009
Posts: 3
Likes: 0
Hard cold start
I have been working on a friends 1990 F-150 w/ the 4.9L I6. The problem I am having is when the engine is cold it is very difficult to start. It will start and stall in a matter of seconds. I have been able to increase the throttle to run the engine at a higher speed to help keep it running. This doesn't always work, as it will pop and crack with increased throttle and it sometimes dies if given to much throttle. Once the engine is warmed up it will idle fine; however, when driving it stumbles and backfires under acceleration. I have checked the idle stabilizer and egr and they are working fine. I have not been able to find any vacuum leaks. Cap, rotor, wires and plugs look good. I have tested the ignition control module to be good. I have checked the timing and it is between 10 and 12 deg BTDC (with spout connector removed). I did notice when using the timing light that the timing was bouncing around alot at idle. Also, when turning the distributor either direction I dont seen any change with the light although I can hear a difference in the engine. I also dont seen the timing advance under acceleration or at higher rpm. What am I missing? Could a bad pickup coil cause this? Any suggestions would be helpful. Thanks.
Check the computer for codes, this thread explains how: https://www.f150forum.com/f10/how-retrieve-trouble-codes-obdi-10907/
I just wanted to make sure since getting nothing would mean the computer might be bad, but since you got 11 then it should be fine. I was thinking timing chain but the 4.9 doesn't have one. It does have timing gears though so you should check them for slack. Take off the distributor cap and turn the engine forward to take out the slack. Then turn the engine backwards and see how far the crank moves before the rotor moves. I think it's unlikely that the gears are worn that bad, but it is possible. Also check the distributor itself. It or its gear could be worn causing slack.