Hi, new to the forum and have found a lot of useful info!

the issue I am having…

I have a 1981 f100 with the 4.9 6cyl, auto tranny. A couple of weeks ago the truck died whilst driving and I assumed it was fuel as the fuel gauge doesn’t work. It still cranked but wouldn’t fire up. I added fuel and then I had a friend give me a jump as I thought it may have needed it as I think I may have drained the battery a little bit at this point.
Anyway, it pretty much screwed the battery and the starter solenoid.
I replaced the battery and solenoid, to no avail. I replaced the starter, and then also changed the ignition switch on the top of the steering column and also fitted a new ignition barrel.

the truck started perfectly, I tried it a few times in the shop and it continued to start perfectly.

I took the truck down the road to give it a run and see how it went.
I noticed the tachometer was fluctuating quite a lot but it didn’t feel boggy or like it was struggling at that point. I decided to turn around and get home as I knew it wasn’t right, then it completely cut out and now it won’t start. It cranks, and will briefly run for about 3 seconds on the first attempt then die again. Anything after that it just splutters.
I looked at the carb and it looks to be leaking from the bottom where the gasket is. The bolts are tight when I checked them.

I don’t know where to go with it at this point. I know the issue is obviously the fuel leaking from the carb. Could it be that I have set the ignition switch incorrectly to cause it to over fuel? It may be coincidence that the float is stuck, but before the initial issue I had there wasn’t any over fueling or jumpy tach? Could the replacement of the parts I have fitted cause this issue?

thanks for the help!

 

Welcome to the forum. Where’s my 11-foot pole?

Lots going on here. First and foremost, charge that poor battery. Most are not fully charged at time of sale.

Next, put away your jumper cables. Those are reserved for emergency situations, such as if you left the headlights on and killed the battery while parked at a strip club. The only person available to give you a ride is your Mom, and she’ll want to have that talk how she’s not mad but is disappointed. Under normal circumstances, jumper cables should never be needed. If the starter system won’t get the crankshaft spinning properly when you turn the key, figure out why and fix that.

Once the battery is charged, test the truck’s charging system. With the engine at a fast idle, you should see at least 13.7 volts measured at the battery.

Next, resist the urge to load the parts catapult (Pull!) in hopes of a fix. Figure out the root cause and correct it, versus making wild guesses. Your wallet will thank you. On a related note, some new parts are total junk these days, especially house brand parts from the discount chains. You run the strong risk of inadvertently introducing new problems. This can be quite the troubleshooting nightmare.

Not sure what is happening with the fuel leak, but that will obviously need some attention.

The jumpy tach? That’s not right, either. That could be as simple as a loose connector at the coil.

One last thing. You mentioned replacing the starter relay (aka solenoid). What brand did you install? Some are junk straight out of the box and don't always release as they should. Some light reading here:

https://www.ford-trucks.com/forums/1...i-mean-it.html

Unless you already purchased a quality name brand, I’d plan on replacing it before it acts up. A bad starter relay won’t cause the problems you’re currently experiencing, but you don’t need to add more trouble.

 

You can eliminate a fuel related problem by opening the choke plate of the carburetor when cold and activating the throttle once. You should see the accelerator pump squirt fuel into the venturi. If you don't see the accelerator pump shot then the next day crank the engine for 3-5 seconds before activating the throttle. This should allow the mechanical fuel pump to refill the fuel bowl if it's draining down overnight.

Of course, if there's an active fuel leak you'll want to address that too.

 

When you are trying to start it, take the aircleaner off. Once it runs for a little bit and then stops, see if you have fuel dripping down in the engine. If you do, the float needle most likely has some dirt holding it open, and fuel is running into the engine and flooding it. If you find fuel dripping into the engine I would pursue that avenue. If not, then look at the other possible sources of the problem. The fuel dripping from the carb may be a clue though of flooding.

 

There are 4 screws at the base of the carb that tend to get loose. You have to remove carb to tighten them. Can you wiggle the top part of the carb?
photo here...
https://cdn.shopify.com/s/files/1/05...g?v=1619767265

good luck