Help me. I am getting so frustrated with this dam truck. Now it won't stay running for more than 10 minutes before it just quits. And I have no idea what or where else to look. Can anybody maybe help me out?

 

No one can help you unless you list what you're working on.

What is the year, series and what engine does it have?

 

Welcome to FTE, John

The best way to go about this is to take your time, and do your troubleshooting in a methodical way. This is a 1970 F100, right? What engine do you have in it? One problem is after 50 years, who knows what's in there.

But, the basics are still the basics. Before getting spooled up and deploying the parts cannon, it is wise to make some very basic tests to see if the engine is even worth tuning up. It will not make smooth power or efficiency if the compression is bad, for example. Modern engines will go many thousands of miles, but in 1970 they were about spent at 75k or 100k, especially if they were neglected. Consequently every tune-up manual always had "Compression Testing" right on the first page. None of us are there looking over your shoulder or can take a look at it, all we can go by is what you tell us.

When a "new" engine comes into your world, it's worth giving everything a once over with a jaundiced eye. Prior owners may or may not have made the necessary maintenance or repairs. Check everything - everything - including that the spark plug wires are in the proper firing order and connected to the spark plugs. Have to expect some hiccups along the way with an old truck, it comes with the territory.

Verify TDC on #1 with a piston stop tool and make sure the timing marks on the balancer haven't shifted.

 

Okay
I have this 1970 F-100 with a 4.9 six in it. When I got it a few months back it was running fine. Had really no issues for as old as it is. But now I figured out that the guy before me had the alternator. Wired wrong so it kept frying alternators and voltage regulators and that little thing next to the regulator (looks like a condenser). Anyway, got that all squared away. But now when it runs the alt. Gauge flickers from zero to discharge. Like the turn signals are blinking. It will run for say 5-8 minutes then start to bog or act like it's running out of gas. Now, no matter how I feather the gas it still bogs out and dies.
Now, it has New starter, voltage regulator, alternator, fuel filter, power steering pump and hoses and, a new carb., New cap, rotor, points, wires. It should be running and stay running. But it won't.
I hope that sheds a little light on my situation. I don't know what to do beyond what I have been doing.

 

It might be running out of gas, as far as the carburetor is concerned. That's why it's important to go through the systems piece by piece and make sure everything is doing what it's supposed to be doing. "Everything ya need, and nothin' ya don't." I don't know that a fuel pump can fail like that or go "intermittent" after a few minutes, but it wouldn't surprise me. If reliability is important in a 50 year old truck, hafta be proactive not reactive.

Also, 1970 means points & condenser ignition. Did it get replaced with those el-cheapo no name condensers recently? Very common for bum condensers these days. Put the old one back in.

 

When it dies, does it have good voltage? If when it starts to stumble, if you turn on the headlights as it starts doing it, does it die immediately?

 

Okay
I have this 1970 F-100 with a 4.9 six in it. When I got it a few months back it was running fine. Had really no issues for as old as it is. But now I figured out that the guy before me had the alternator. Wired wrong so it kept crying alternators and voltage regulators and that little thing next to the regulator (looks like a condenser). Anyway, got that all squared away. But now when it runs the alt. Gauge flickers from zero to discharge. Like the turn signals are blinking. It will run for say 5-8 minutes then start to bog or act like it's running out of gas. Now, no matter how I feather the gas it still bogs out and dies.
Now, it has New starter, voltage regulator, alternator, fuel filter, power steering pump and hoses and, a new carb., New cap, rotor, points, wires. It should be running and stay running. But it won't.
I hope that sheds a little light on my situation. I don't know what to do beyond what I have been doing.

As far as I can tell with an electro meter at the battery while running the meter shows right around 13volts. When I put in the plugs points condenser and rotor and new carb. I didn't skimp on cheapy parts. Also I realize that 30% of new parts can be bad right off the shelf. This is a new to me problem

 

Yeah we heard ya twice the first time.

Well the parts cannon appears to be fully operational, at least.

What is the quality of the spark when you test a grounded plug right now? Then, when it dies after a few minutes the next time, be ready to check spark. Pull a plug wire, install a spare plug and crank it over with a remote starter switch. Need to see a blue spark. Not yellow. Or, even easier just pull the coil wire. Should jump 1/2" to ground.

Basically first rule out ignition, then if OK look at carburetion or fuel delivery from the pump as mentioned. Maybe choke problems. These are simple beasts, you'll get 'er.

 

My guess is coil at this point, if you’re sure of the rest of the system.

 

You can eliminate a fuel shortage, if it is, by installing an electric pump.

 

Is your coil going out?

 

No it
​​​​​​ isnt

 

This is where i'd be looking, as well. If everything's good, and then it falls on its face...could be the coil overheating.
how much voltage do you have at the coil + terminal with the engine running? Do you have a spare coil laying around that you could test with?

 

Could be your fuel line. Is it crushed in or kinked somewhere?
It's a long long shot but look at the fuel sending unit and check for silicone. I had a friend who used silicone to seal his. Each one of the screws pushed a little bead of silicone into the tank.
They swelled up to the size of grapes and one day when his fuel got low one of the grapes got sucked up against the intake tube.
That was hell to diagnose!

 

I hope this is the time for a little diversion....I know when I am frustrated a little fun and some time away are just the ticket...pushing too hard to find out whats wrong wont get it all the time just the way you want it.....be patient and methodical....

Ok time for a story inspired by Millam z post....My father was Mr Fix it for his far less than handy friends. We had a family friend who while a great guy was about as handy as the wall is at fixing stuff. My pop would install dishwashers etc for his friend Zal. Zal was a municipal court judge. who had a wit like a vipers fang are...sharp and very quick. he was funny as heck..The Zalman family was experiencing a toilet that just would overflow here and there out of the blue...this was a young family no teenagers etc to do their business and plug it up....you know little kids 10 years old and under.3 girls and a baby boy...this toilet was frustrating my pops....its a simple devise why was it out of the blue plugging up? My pops had enough...he was determined to find out why it was not letting the water flow...finally after 90 days of this stuff, he dragged the toilet out to the back yard and was just about to take a hammer to it to expose its insides when a gleam of sunlight hit something at the bottom of the bowl where the water drains....there was a toy in there...a CLEAR dolls baby bottle in the shape of a coke bottle that would flip occasionally to block the flow of water....kinda like the silicon grapes in Milliam's story.....there now the diversion is done...go find and fix this thing....I bet there is a hole or a crack in a rubber fuel line somewhere....does this truck start back up with a squirt of either or brake cleaner directly into the carb?