I have a 1990 Ford Econoline E150 Club wagon 5.8. This van is in very good mechanical shape. However I have a gremlin. After its been sitting for 8-10 hours over night in the morning it starts just fine in fact it starts great every single time. However for the last month its been doing a very weird thing. After I start it in the morning and I make my way on my journey to work about 10-15 mins it stalls. It either just stalls and you have to start it again or it kind of just does a cough and it takes off again. And you can pull over and put it in park and start it up again no problem and drive for the rest of the day for 8-10 hours turning it off and on as you do errands and it never stalls again till the next morning after its first start. And its consistant 10-15 mins after starting. It gives no symptoms like hesitation or stumbling before it does its like some one just turn the key off. Just once in the morning when I go to work like it rebels going to work every single morning. Now I removed the front tank and kept the back tank. Took the tank off and check it and its clean as a whistle and pump screen is clean. I changed the fuel filter cause the fuel in the back tank was very old and dark yellow when I got it so changed the filter after that tank was done. Kept putting seafoam in it and Lucas engine cleaner every tank. I have not done the fuel pressure test yet but that will be this weekend. Just wondering if you all here have any suggestions. It appears to have started after I took the second tank out but I'm not totally sure about that timeline. I have a new high pressure fuel pump. I have changed almost every part on this van to get it where I would like it to be for a long road trip. Changed the gas cap as well. One question is why do I have two hoses coming off the back tank filler? I don't understand some of this mechanic stuff as I work under the supervision of my brother. He tells me how to do it and I do it cause I have to learn about my van myself. Besides he likes telling his sister what to do. LOL

 

At this time we don't know whether it is fuel or spark related, but we can do a few little things to get some idea.

You may be on to something when describing ,"Just like turning the key off".

On the ignition coil is 2 terminals. One brings power to the coil when the key is turned on. What I would do is ,rig up a test light so it can be seen when driving the vehicle.
What we are looking for is a possible loss of power to the coil when starting the day. It could be a problem with the ign sw,, but the only way to know is to watch it and see if it goes out at any time when driving. We DO NOT go replacing any parts until we prove it is either defective or malfunctioning. First we determine which wire to the coil is bringing power to it with the key on. The plug has to be removed to verify this. We now can clip the test light ground clip to that wire, bring the test light out so we can close the hood leaving the test light on the outside.Now we set the point of the test light on a good ground and with the key on the test light should illuminate.
Secure the light so you can drive the vehicle and watch if the light goes out when the vehicle stalls. You will have a visual picture if what is happening. If it goes out and the vehicle stalls ,you know it is involving the ign sw assy on the lower part of the steering column inside the vehicle.
If the light never goes out and the vehicle still stalls ,we move to another system.