Been a few years since ive posted here.but I'll give it a go anyways. Basics are 1994 150 4.9 i6. I ran into issues where the engine would just intermittently cut out driving down the road, almost as the computer would shut off for milliseconds and reengage. I ordered a new ecm and I had similar issues still. After days and days of chasing this issue, I noticed something as I drove away one afternoon. I have a habbit of turning off the overdrive when I first pull away. As the motor would start cutting out I hit the overdrive button and I realized it would run properly of I pushed and held the over drive button. I ultimately wired a switch to hold voltage across the switch as a test and I confirmed it. Power held across the switch keeps the motor from cutring out, but I lose my overdrive, which is pretty inefficient at 70 mph.

a few things that I have done, because I thought it could of been a few different things because of the way symptoms presented..
replaced forward fuel tank, never use the rear tank
Pulled entire engine harness and checked for charging all the way down to the trans wiring
Checked for codes, none popped
Checked interior wiring for chaffing
Replaced fuel cut off switch
Fuel filter

I know thats long but is a weird gremlin to be chasing. Anybody have any ideas on this issue?

 

Have you tried replacing the actual OD switch? I think they are about 12-14 dollars on amazon. I bought the switch and ring that goes on the end of the stalk. Does the "OFF" portion light up?

the complete lever is about 40 to 45 bucks if I remember right.

 

Just a side note; no such thing as no codes. you will get a Pass Code if no faults are found. There are usually some continuous codes present.

 

I have not replaced the switch but I did check it for proper operation with a meter. Honestly I would be floored if that's the cause of this. Thankfully this truck is no longer my daily driver, so I am in no bind to get it fixed but its eventually going to be my daughters vehicle because she wants it. I'm almost to the point of buying a donar truck to replace the harnesses. A few more things I can do before I get to that point but its not far off.