2 pages and I only see 2 people say he need to narrow it down to gas or spark and not run around in circles like he has done.
Now he said when he stopped 1 time and popped the filter gas was coming out the carb guessing vent?
A bad needle / seat or float will cause this not a power valve. A high float level will make it run rich as will a bad power valve.
But OAT should have nothing to do with it shutting down if it was a carb issue unless icing up in my book.

He also said that it kind of sputters when it stops, gas out the carb top, black plugs is kind of pointing to a needle / seat / float level problem.
When it does shut down do you smell gas? It may not hurt to rebuild the carb if for nothing else for peace of mind knowing it is clean, has a new needle / seat and float level checked.

BTW I been running a NAPA top of the line, same as the OP, ICM for the lest 5 years without any problems.
I would not run any cheap bottom of the line ICM as it will soon fail leaving you stuck on the side of the road.
BTW if you still have the old ICM might want to throw it on to see if it changes anything but keep it in the truck as a spare.
All you have to do is plug it in no need to bolt it down if you dont have tools to do that at the time.

But till we know 100% it is a gas or spark issue we are ALL just guessing.
So tell us when it stops do you have gas and / or spark each time?
Dave ----

 

And this also -

Quote:

- fuel pump (I went through 3 before I got one that worked)

Today's fuel pumps are junk. They usually are not calibrated as to deliver correct fuel pressure (too high) causing flooding. You have to put a gauge on it and if too high use a pressure regulator.

If a fuel cap is taken off and it spits, the EVAP for that tank may not be functional.

 

Interesting thread. This vintage truck can be driven in cold weather with complete success. I drove them when they were daily drivers. Carb icing can be a real problem as mentioned by others. The heat mechanism from the manifold to the air cleaner must be working. Do not overlook old cracked wiring that shorts out when wet.

 

Now that I read through this again I need to revisit my comments a bit. I was thinking bad power valve but got turned around a bit not thinking about what could overwhelm the carb and cause a rich condition combined with fuel spitting out the vent. Fuel pressure.

OP, you need to get a fuel pressure gauge on there. As mentioned multiple times, fuel pumps these days are complete garbage. If your pump is doing what one of mine did it is pushing out way too much pressure and overwhelming the needle and seat hence the fuel pushing out of the vent. You want no more than 6psi coming out of the pump. The pressure in the tank is not helping either. It clearly isn’t venting properly.

The power valve may well have been blown out as well, but start with the fundamentals of verifying good fuel pressure. If it is within spec, at least you can check that off the list.

 

If you don’t have a compound vacuum/fuel gauge now is the time to buy one. It is absolutely required for vehicles of this vintage and isn’t very expensive. This is cheap Chinese crap but it has worked for me for five years now. Good enough for the average shadetree mechanic.

 

As a general rule, not 100%, but typically, a fuel system issue will stall sputtering. An ignition or electrical failure is more immediate on/off.

 

A methodical approach is needed above all else. Plan. Measure. Verify. Cross it off the list. Repeat.

Fuel pressure a fine place to start.

Spark is a fine place to start.

 

It's just mind boggling that it's not carburetor icing, my god if it's below 50 degrees that's always the problem. go figure.

anyway, that plug is way black. I can't tell in the picture but if you're not burning a lot of oil, you're running way rich. I would stick with carburation, rebuilt doesn't mean fixed. but I'd look at how hot your spark is too, it should be blue.

 

It is just this simple -

When it shuts down -

1) Remove ACL lid, look into throttle bores for flooding or icing (yes, contrary to popular belief here, it does happen and is more prevalent in certain geographical areas [high humidity] - and no, it doesn't have to be snowing), work throttle and verify fuel with accelerator pump shot

2) Verify spark by grounding a plug wire.

This is not rocket science. 38 posts and the young lady is no nearer to diagnosing than when she first asked for help.

And what beats it all is she took it to a shop and they couldn't figure it out other that pointing a parts cannon at it and still charging after no fix.

BTW - If one shuts off or is hard to start, hold the accelerator pedal to the floor and see if it starts (flooded or choke hanging).

If it has dualing tanks, switch tanks as the vent/EVAP may be bad on that one tank (or remove filler cap).

 

After reading through this, a few things, you said gas game out the rear tank when you took cap off, you need to make sure you have a vented cap on both tanks or make sure your evap system is working correctly. Personally, I would take off your carb and rebuild it, the ethanol in gas will eat up the needle seat and can cause flooding, intermittent or constant which could be causing your black plugs, I had to rebuild the Holley on the 79 I sold to my BIL in MO after 6 yrs or so being back there. I made him promise to only get the 93 octane with 0 ethanol in it moving forward, since then (2023) it has been fine, he was struggling with the same issues of dying off n on. X2 on the grounds check, one loose could cause issues.

It's hard to diag over the interweb, but the main thing is to eliminate one issue at a time, pick one and start from there. Rebuild carb, check fuel system/evap system/vented caps/fuel pressure/fuel filters (also have had the issue of water in the tank, it mixes with the fuel when driving then you may get a big pocket of it come through and kaput, add that in to a stuck or sticking needle/float that floods it (black plugs) and it'll be a hard find. Heet helps, but will not remove large amounts of water in the tanks. When done with fuel and if you still have the issue, start on spark/ign, you've already thrown a lot of parts at it, time to step back and take a systematic approach to diagnosing with one system at a time.

 

Quote:

- 2023 rebuilt carburetor, replace choke pull off, float & fuel filter (the truck has the original motorcraft carb)

 

I hear a lot of suggestions about using zero ethanol gas. I’m not sure where all you guys live, but y’all must be very lucky. In Michigan (where the OP lives) zero ethanol is not available anywhere unless you pay nearly $7 per gallon from one of the stations that sell stuff that people usually get for their watercraft.

Just go to https://www.pure-gas.org and look up the city she lives in (Grand Rapids). There are all of two stations that sell E0 and I guarantee you it’s at the price point I mentioned. Who can afford to pay that for a daily driver that gets all of 10MPG on a good day going downhill?

Used to be that you could find a station using that site where they had zero ethanol in all of the fuel grades at the same price as E5 or E10 stuff, but those days are long gone. Hell, when I need zero ethanol stuff I just go to my local airport and fill up my cans with 100LL. It’s actually cheaper than getting 93 E0 from a station. But again, not only is it expensive but you can’t exactly pull your truck through the gate, onto a taxiway, and up to the FBO to fill up every three days. At best you would be kicked out, at worst arrested. I walk in with a few cans and use it for my model aircraft engines. Five gallons lasts a year.

These days any type of E0 isn’t practical, affordable, or reasonable for use in a vehicle that’s driven regularly in our area.

 

Going back through the symptoms, I thought we might revisit this. When you say all electrical cuts out, does that mean you lose everything, lights, radio, etc.? That sounds like a main power connection, and ignition switches are not immune from these kinds of problems. Wiggling the key or cycling the switch may bring it back together temporarily. I hate to hail mary another wild guess into the mix, but a faulty ignition switch could be a possibility, working intermittently, from those symptoms.

 

I was wondering about that too, but glossed over it since most people use the term “lost all power” as a reference for an engine stall. However, it seems like she might be saying that all of the electrical components black out when the stall happens. Another “however”… if I am interpreting the comments correctly it seems like the engine will crank but not start after the “loss of power”happens. There are clearly multiple issues here. I will reiterate my opinion that checking fuel pressure needs to be a first step. Maybe it isn’t the issue, and I’m more than happy to say my premonition is flat out wrong, but at least that can be eliminated as a problem once there is a data point. Data, not arbitrary parts being thrown at the engine, will solve the problem.

 

More opinions: I was waiting on the diag results for Air, Fuel, Spark before launching into wholesale electrical “WTF is happening?”

As the OP has admitted she’s newer to this stuff, and is daily driving, hopefully the electrical can wait a bit. I’ve also known people to get rid of rigs or bikes after ripping half the electrical out and being unable to piece it back together. I’m an electrician and regularly go “oops” or “wait, what?” wiring on my truck; admittedly 12v DC is not 120v-25kv AC.

Let’s stick with one foot in front of the other, and hopefully not completely overwhelm this poor gal with all our best intentioned advice.