85 F150 Fuel Issue

[ChitownBullnose]

This is my first question to the group. I appreciate the warm welcome previously.

Reminder, I have an 85 5.0l 302 V8 w/2150 carb and dual fuel tanks.

Been working through an issue with the truck stalling. It idles in park very cleanly, but stalls out when driving. I cleaned up the carburetor and checked/cleaned the accelerator pump. All seems to be working well there. I was able to drive the truck around the neighborhood for about 10 minutes before it stalled on me. There’s definitely enough fuel in the front tank. The truck idles very well and I was able to crawl it back home (good thing I didn’t venture out too far).

I am now thinking it’s a fuel filter or fuel pump issue, but I’m having trouble identifying the part. Here’s a couple pictures below of what I am not 100% sure. I wasn’t seeing a fuel filter or fuel reservoir like some other dual tank 85 F150’s have.

Thanks for any ideas or suggestions.

[Gary Lewis]

Ben - I believe your pics are of the "fuel tank selector valve", which is shown in the lower left of the schematic below, and since it only has three ports that means you should have a traditional mechanical fuel pump on the engine.  And while those fuel pumps can fail, I don't remember them causing the symptoms you are seeing.

Looking at the EVTM I see that you should have the EEC-III system, which controls ignition.  If the pickup in the distributor or the TFI module on the distributor are failing they can cause problems when they get warm.  And you said the problems started after ~10 minutes of driving, right?

Give us a few more clues on how the engine ran when the problems started.  Did it happen suddenly?  When does it clear up - after the truck sits and cools off?

[ChitownBullnose]

Thanks, Gary!

Yes, seems like it takes about 10 minutes of driving before it starts to sputter then stall. It will idle in park for as long as I let it. I didn’t ‘feel’ anything weird driving. When I restarted it, it idles strongly, but wanted to die when I pressed the accelerator.

I hadn’t thought of the distributor yet.

I’ve only driven it a couple times now, so not sure if it’s just when it heats up but that seems consistent.

[Gary Lewis]

The Thick Film Integration (TFI) modules are notorious for failing.  I'm not 100% sure what the symptoms are, but I do think they can allow the engine to run, albeit poorly.

In later years Ford moved the module to the fender to get it away from the heat of the engine.

We do have the STALL/NO START: TSB 87-6-10 on the site, but I'm not sure it is the one you need.

[ChitownBullnose]

I’ll investigate this further and report back. It really does seem consistent with the issue. I can start it up cold and it idles fine, but briefly sputters and stalls after about 10 minutes. It’s then hard to start back up.

Thanks, Gary