1977 F150 400 C6 4x4 Ranger XLT

I am a young lady in my early 20s, I live in Michigan, and this truck is my daily driver. I am the fourth owner of this truck, recently purchased this summer from the vehicle's third owner in Colorado who used it for hauling logs on his mountain property. The second owner was a mechanic who continued to do all maintenance and work on the vehicle for the third owner. The truck is in great shape and was supposed to be a get in and go truck. I have the records from the mechanic detailing the work he has done on it.
Previous work includes the following:
- 2013 exhaust leak repair
- 2014 rebuilt C6 automatic transmission, replaced transfer case, replaced front steering linkage, replace trailing arm bushings, alignment, radiator repair, replaced water pump, replaced thermostat, replaced timing chain and gears, replaced front and rear u joints with greaseable joints
- 2019 replace steering column, replace broken shifter collar
- 2022 replaced track bar bushings
- 2023 rebuilt carburetor, replace choke pull off, float & fuel filter (the truck has the original motorcraft carb)

The truck was running great over the summer but I had a few issues. In the summer I had to replace the following:
- battery
- alternator
- voltage regulator
- starter
- fuel pump (I went through 3 before I got one that worked)
- fuel filters
- ignition coil
- spark plugs
- timing adjustment (due to the truck being in Colorado, the timing was set to 20, I adjusted it to 12 according to the engine specs on the vehicle)
I also spent a weekend doing brakes
- rear brakes and drums
- front breaks, calipers, rotors, bearings and races, and front lines
- when doing the front brakes, I cleaned all hub parts and regreased them

This may be more information than you could need, but here is the current issue:
The truck keeps stalling and leaving me stranded on the side of the road. This has been a consistent issue since it has gotten cold out, anything below 30 degrees. I've done some carburetor adjustments because I couldn't get it started in the cold. I adjusted the choke to 3 rich (according to engine vehicle spec) and turned the fast idle up. Since doing so, the truck has been starting well and idles decently while warming up. When a strong gust of wind comes along, the truck stalls when warming up. I am able to get it started again and once it is running, wind doesn't seem to be an issue. TI live in an apartment, so I don't have a garage or any place to work on it during the winter. I have brought it to a local mechanic for this issue 3 times.
They have done the following:
- replaced ignition control module with an echlin brand unit
- checked for vacuum leaks
- replaced distributor
- adjusted timing
- adjusted air to fuel ratio
- replaced the vacuum motor on the air cleaner
- installed hot air intake tube
- fixed a kink in the fuel line from the fuel selector switch to the fuel filter
- replaced the fuel pump due to pump leaking oil (this is now fuel pump #4)

After all of these things, the issue still persists. This past weekend the temperature was in the upper 30s, low 40s. It started and drove with no issues; I took it on the highway, made it up to 80mph no issues, ran some errands with no issues starting after parking and no issues getting home. This morning (22 degrees, feels like 7), I was on my way to work and the truck stalled after 2 minutes of driving. I could not get it to start at all. It would crank, but not fire up. I let it sit for about 20 minutes and tried again. I could get it to fire and run for a few seconds and then it would stall again. I tried jumping it as a last resort before calling a tow truck, it did not help. I've attached pictures of the engine as it exists currently. I also have some pictures prior to taking it to my local mechanic, let me know if those would be helpful.

I need any advice I can get to fix this issue. I've searched these forums, watched videos, and reached out to the second owner for his advice on several occasions. Everything I can find says to replace the ICM, distributor, ignition coil, plugs, fuel filters, fuel pump, ect. all of which I have done. Is there anything I am missing? Is this truck not capable of running in the winter/being a daily driver? I love my truck and I don't want to sell it but I cant keep getting stranded on the side of the road. Any and all advice would be much appreciated.

Thank you



I've ordered the plastic tubes from LMC, this tube doesn't seem to stay on very well.

Not sure if the vacuum advance is hooked up properly, I cant figure out where each line comes from and how that system works due to the many switches.

Taken on 12-23-25, no changes have been made since

Replaced gas line, they looped it to prevent any kinking.

 

Does it do it on both fuel tanks? it sounds like you have water in the tank and it's icing up and plugging your in-tank screen. also any water at all will plug that stock filter on the carb. I always drilled out that filter and put a standard inline one on.

You can't adjust your choke by the marks, you have to go by what it's doing. adjust it cold to where it just closes. then make sure it's wide open after warming up.

 

Welcome to FTE. Nice rig. The truck should absolutely be capable of being used as a daily driver in this weather. What do you think people drove in the 70’s when the same ol’ Michigan winters were around? I’m stuck in this winter hellscape as well (Ann Arbor area) but I think I’m a little south of you based on your temperature observations from this morning. My two stroke snow blower fired up fine. Your truck’s much more sophisticated fuel and ignition systems should have no problem doing the same thing when it is working properly.

You mentioned a lot of ignition parts, but I don’t see a pickup coil on that list. They love to fail when they get hot. Maybe it was included with the new distributor but I didn’t see it specifically called out. Figured I would mention it.

Your fuel pump issues are not unique, so don’t feel bad about that. Thanks to a lot of jobs and manufacturing from around these parts being shipped overseas the quality has plummeted and you cannot simply spend a little more money to get a quality part. Fuel pumps of the vintage our trucks use seem to have suffered worse than a lot of other parts.

 

The pickup coil can certainly cause it, I assumed it was doing it before he put the new distributor in, if it started after the new distributor then the PU coil is very suspect. the new ones are garbage.

But that wouldn't explain it only stalling in cold weather though.

 

X2 on what Viper said ...might be time for a new Motorcraft ICM as I didn't see one on your laundry list of replaced parts. The other culprit could be the magnetic pickup inside the distributor....if I remember correctly it's called a stator. Usually just easier to buy a new distributor and drop it in. Notice I specifically said Motorcraft ICM....parts house stuff is not that reliable these days. It might get you down the road for a day...a week or a month who knows. Others have also fought with cheap stators until they found some NOS parts on the interwebs. (NOS = new old stock) Hehe I'm not talking nitrous.
*EDIT* My bad ...OP did state that the ICM was replaced. The Echlin should be ok.

 

Yeah, I think there might be more than one issue going on here.

Incorrect fuel delivery when cold (one stalling issue that she seems to be able to get around eventually) and then the second stalling issue after the engine warms up and has been operating for a little while. That made me think of the pickup coil.

 

Is the choke closing tight due to the cold air episodes? Seems like that engine is buttoned up properly but if the adjustment is already tight, a blast of cold air might tighten it up resulting in the stall.

 

Cold air is just cold. it will cool objects as it robs heat. Fast moving cold air will cool objects faster. Water freezes at 32 degrees. Air as in atmosphere has a water vapor, we call it humidity.

Don't know that it is your issue, but with a 1979 Malibu 305 once went to visit friends in NoVA for Christmas, we had a bitter cold snap, 5 degrees and wind, the car would stall and have to sit. Puled the air cleaner, saw ice forming in the carburetor throat. Eventually tried wrapping the carburetor and made sure the wrap did not have chance to get in any of the linkage. Wrapping the carburetor so linkage was not affected was tricky, was kind of like laying / tying a blanket on top so engine heat was maybe held under the blanket, above the plug wires, hoses, etc to block air from fan. Finished the trip, then when at home again, changed filters, etc.

In other situations, I have blocked off the radiator with carboard in front behind the grille, most of it, but kept eye on the temp gauge.

Your truck might be icing at those temps.



YELLOW CIRCLE
That foil like inlet hose on your truck likely used to attach to a stove like shielding mounted on the exhaust manifold, your silver flex pipe looks like it doesn't. If attached, it'll supply warm air. If hanging loose, it'll supply cold air as the shield blocks it from the manifold. Might help to move that foil tube over between the heater hoses and engine too.
GREEN CIRCLE
When vacuum is present in the small vacuum can, the air valve shuts, and instead of pulling air through the big inlet, air gets drawn through the foil pipe, hopefully heated air.

Just a thought.

 

Thank you everyone for your quick replies. To answer the questions that have been asked:
1. The issue occurs on both gas tanks. The local mechanic cut open the fuel filter that comes off the fuel selector switch to determine if there was any gas tank debris, he found nothing. I don't know the state of the inside of either gas tank or the filters on the fuel pickup tubes in the gas tanks
2. I adjusted the choke and fast idle over a couple of days. The choke is closed before starting, but loose enough that pushing it with my finger can move it. I've watched it throughout warmup and after driving, the choke opens fully.
3. I am in the Lansing area. I would think it would be capable of driving in winters, but the mechanic is telling me that this era of truck doesn't run well on modern fuel, especially in the winter. I did a bunch of research before purchasing this truck and never heard anything about this being an issue.
4. The mechanic suggested the pickup coil could be the issue, but due to labor costs, we decided to replace the distributor instead of just the pickup coil. The new distributor is from Napa. Is this a reliable brand or would it be better to find an original motorcraft one (going to a junk yard or off facebook marketplace)?
5. I did replace the ICM, but its a Napa ICM (Echlin) not motorcraft.
6. The silver flex pipe doesn't seem to fit very snug. At highway speeds, I can hear it shaking around and vibrating. I've ordered a plastic one from LMC for both the hot and cold (havent gotten it yet). It should be connected to the manifold. I have the ford shop manuals and referenced the diagram in it

 

the stove pipe is cool and all but it has nothing to do with your problem. except, if the flapper is closing on you choking the engine for air. might block it and see if anything changes.

From what you're saying ice in the tank, or at least junk or varnish plugging the screen sounds even more likely to be your problem. when you shut it off it falls away and runs again until it sucks enough back on and dies. you might dump some Heet in and see if it helps, but if it doesn't you still can't rule it out.

 

Throwing an idea out there. Take a look at your ignition coil. Unplug it from the coil. Plug it back onto the coil. Assess fit. Is it tight? I mean snug and without movement? It should be Newer repop coils sometimes have just enough play to stop you cold mid-drive. I had this happen on two occasions with low-end parts. Easy check.

While you’re in there, confirm voltage to coil. And check battery connections. I’m sure they’re fine but just to be sure….

 

What is the relative humidity when she cuts off (get info off weather channel)?

It sounds like the CARB may be icing. It will ice and cut-off and as heat from the engine warms and melts the icing it will start again.

Is it a 2V CARB? Do you know what a HEAT RISER VALVE is and where to find it?

A properly operating choke stove (heated air inlet) is a must in your area.

If the choke is functional and properly adjusted, all that is needed is one full accelerator pedal depress, release and take your foot away from it for a cold start. You touch the fuel or pump it and it will disturb how the chokes operates. Let her warm on fast idle for a minute or two (especially up there).

 

Carb icing is a real thing. That's why carbureted aircraft have this.


In a car/truck it isn't a big deal. You just pull over. In an aircraft you're dead if you forget about it. The phenomenon happens because of accelerated convective and evaporative cooling that occurs due to the increased velocity of the air and associated pressure drop due to the Venturi Effect. Ice starts to build up around the carb throat and air can no longer move due to the restriction. We have experienced some abnormally cold temps in this area for November and December. I wouldn't think that 20-30F would cause an icing problem, but 10-20F sure might and we have seen a lot of that. That's a guess though.

Aside from that, I would seriously consider installing a fuel pressure gauge and monitoring it. Possibly run the thing into the cab so you can keep an eye on it. The more data you have the better off you will be in regards to solving the problem. Congrats on being a young person and having the knowledge you do along with the desire to learn. A lot of folks your age don't even want to get a driver's license. Reading your post would be like trying to read Aramaic for them. Keep coming back. You can get this figured out if you keep with it.

 

Yes it is on airplanes and snowmobiles, but in many years running pickups in temps as low as -30 I've never, ever had a problem with it.

I can't say what the OP's problem is for sure, but it's not carb icing under the conditions he says with a factory air cleaner.

 

I’m with 440sixpax. Focus on the easy stuff - and the easiest to overlook. Fuel pressure, electrical connections, etc. For it to shut off mid-drive, those are good places to explore. Fuel, air, spark. The parts cannon didn’t work. I’ve learned it’s always in the last place you look. Keep looking, be methodical. You’ll get it.