1991 F-150 351
Truck stalled 50 miles into my trip, and would not start for the next few minutes. After sitting for 15 minutes it started and ran for 1-2 minutes, but then stalled and would not restart. 30 minutes later it started again and idled for 2-3 minutes but sputtered when I pressed on gas, and eventually stalled.

Next it would start and idle for a minute before stalling when I started looking at it. After connecting a fuel pressure gauge between the filter and engine, it idled for 3+ minutes until I turned it off. Fuel pressure was between 30-35 PSI.

Removed the fuel pressure gauge and it ran for 5-10 min, then rough idled until it stalled.

Previous owner added a 2nd fuel tank and modified the fuel delivery in the process. I discovered the Frankenstein configuration recently when investigating why the front tank pumped gas into the rear tank. To simplify things, I replaced the Dual Function Reservoir with a filter (I found no filter outside of the tank previously). The rear tank is disconnected. I have no high pressure fuel pump on the rail. The fuel lines are all rubber with hose clamps.

I'm not sure if the problem is even fuel related, it's just my gut. Debating replacing the fuel pressure regulator. I've tried to get the fuel pressure on the rail, but the gauge is not getting a reading. Gauge never moves even if the truck starts and runs, so I assume I'm not using a good adapter.

This truck is great condition so I'm not opposed to spending money to replace everything from the fuel tank to the fuel rail. Or even the injectors if there's a good alternative. The 2nd tank is fine, but not necessary for my purposes.

Thanks.

 

Replaced the fuel pressure regulator and it behaved the same way. Idled for no more than 5 minutes then stalled.

 

So much money is wasted on new fuel pressure regulators because they are not understood. Their job is to keep the pressure from going too high.

I would find a way to properly connect your gauge to the fuel rail and situate it so you can monitor it as you drive. Don't overlook the possibility of a loss of spark or drive to the injectors due to a capacitor issue within your computer..

 

Add me to that group that waste money on fuel pressure regulators.

I connected the gauge to my tire and it worked flawless. Since the fuel rail and tire both should have the same valve, I just looked for a difference. The center pin in fuel rail valve is so far embedded it's not being pressed in. I'll replace that valve tomorrow.

 

Replaced my fuel rail valve with an identical one that I still can't use. At least it is shiny and has a cap now.
Great explanation of the difference between a Ford Schrader and all other Schrader valves.
https://www.ford-trucks.com/forums/1...-question.html

No codes with KOEO nor KOER, but it didn't stall during the test, so no surprise. The ignition coil resistance is 8.7 when cold and 9.4 after warming up and stalling. I think my options for next step are to replace part or all of the distributor. If it's more complicated than that I probably need a mechanic.

 

Run it around with test equipment on it
In the shop, you can just run it with two spark testers on it and 2 test lamps on the coil
You need to monitor both sides of the ignition coil in case the ignition switch is flakey
That ignition power to the coil from the key should still be there as the truck dies
The negative side of the coil should blink constantly, see to it that it does or does not as the truck dies
That blinking (the pip signal) comes from the stator in the distributor

 

There's a decent amount I need to research in order to understand some of that. I don't have spark testers or test lamps.

My hope was that it was either the ignition module on the side of the distributor, or pickup coil inside the distributor, so I replaced the entire distributor. It ran for about 20 minutes, died, and won't start.

I gave up and towed to mechanic who confirmed the continuity was fine in ignition coil, but test lamps indicated it's bad. Next time I'll learn how to test it that way.

 

Is your battery charging when running? I had a stalling issue like that when the eyelet on my charging wire rusted out.

 

volts is 14.5 when runnning. Today it ran great and yesterday the ignition coil was replaced so I’m hopeful that was the only problem

 

I used to have a similar issue and it turned out to be a clogged breather tube causing vapor lock.