While riding along, the truck stalls out. acts like vapor lock.
When it does that remove the gas cap. If there’s a vacuum there’s a problem with the venting. Could also be a weak fuel pump. How long have you owned it? Miles? Did this just start happening?
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I’ve had the truck 15 years and the fuel pump is new. I was thinking that it may be collapsing the vapor line since it has never been replaced. I also wonder if the gas line needs to be replaced.
The ignition control module may be failing.
When these start to go, you can be driving along and then the engine shuts off. Sometimes the engine will start right away, and other times it may take some cranking before the engine restarts.
This was such a common problem with Fords of that era that I had two modules mounted under the hood…One mounted on top the other.
That way, when one module failed and left me stranded on the side of the road, I just got out, opened the hood and plugged the spare one in and I was on my way.
Tester
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Thank you SO MUCH! I will check it out!
Tester said it right. I had a 78 Ford pickup and that was the problem. A bad module will get really hot. The parts person may ask if yours has a blue grommet or black. You should have the blue, like the one in the photo. It may look black from the top but will be clean underneath. Unbolt it to look. It’s near the hood hinge on driver side.
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I own an early 70’s Ford, no ignition module. But in the case of a 78, my first suspicion matches up to the posts above, ignition module problem of some sort. To narrow it down, when this happens next time check for spark during cranking. If no spark, a faulty ignition module is looking even more likely… Easiest way for the spark-test is to bring a spare plug with you.
Thank ALL of you guys for the information! THAT was the problem. In 25 years, I had never changed that module!
Respectfully!
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My dad had a 67 F150, purchased new. For some reason he decided to install an electronic ignition module. Ford didn’t offer anything like that at the time, so he home-brewed a unit. Before this modification, the engine ran perfectly w/the oem points configuration, but he decided anything using electronics must be better … lol … after electronic ignition, the engine would stall out anytime it rained … lol … he had to set up a switch to turn it on and off, off when it was raining. On when dry. When “on”, no difference in engine performance … lol …
I think the main advantage of electronic ignition is slightly better emissions, and it probably works better at very high rpms, near the engine red-line. But who runs their engine near the red-line? Not me.
In general? No points to adjust/replace ever, same for condenser, plus computer control of ignition timing for better emissions, power, and fuel economy. LOTS of benefits.
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Better control of ignition timing seems a good thing in modern electronic ignition systems. But not sure what set ignition timing with Ford’s 1978 version.
You set the static timing and lock the distributor down in place, the vacuum advance and electronic ignition module controls the dynamic ignition timing… Use a timing light to see what it is all doing while running…
I thought Ford’s 1978 configuration also uses the distributor centrifugal advance. No?
don’t see one on a 78 5.0L F100…
Hard to say yay or nay from that photo, any advance weights would be located underneath. If you had one to inspect you could see if the shaft twisted from the default position a little.
I don’t remember, been years since I have messed with a older Ford ignition system… Like you said, would have to put my hands on one to know either way (good chance it does have mechanical advance)… I’m more of a hands on person, if I can put my hands on it I can figure it out for the most part…
Most replacement distributors listed for this truck on Rock Auto have a note “Without Governor”.
Duraspark II ignition control modules can have load and altitude electronic spark adjustment.
Ford EEC (Electronic Engine Control) with full electronic spark control was introduced in 1978, but not on trucks.
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