selrox

A little over 2 weeks ago I purchased a 1978 F150 with a 400CID.
Just for hauling stuff and driving around if neccesary.

It ran good the first couple of days but a week ago it started acting up.
After driving for a few miles it wouldn't start or just stall out and wouldn't start.
After letting it cool down and me pooring some gas in carb it would finally start up.

Decided to replace fuel pump, fuel line to carb (to prevent vapor lock), plugs, wires and altenator.

Didn't help.

Now, even after pooring some gas in carb it won't fire up when hot (it will sometimes after the truck cools of)
Noticed when I took line to carb off and cranked it there's little to no fuel coming out so I guess I have to check fuel line that's going to tank.
When I pump the pedal I can see 2 litlle squirts of gas going in the carb.

Shouldn't it fire up when I put some gas in carb or connect a separate gas can to the carb ?

Well...it doesn't.
It just backfires BAD
Could it be flooding ?
Could it be that the float need adjusting ?
And can the float level just change for no reason ?
I believe its a Motorcraft 2100 or 2150

I really need some help.
Being origanally from Europe I'm not familiar with US carbs and engines but.....I'm willing to learn

I really like this truck but after already having to replace powersteering gear box, starter, fuel pump, fuel filter, plugs and wires I'm afraid this truck will nickle and dime me to death
My cashflow is kinda well.............tight

What could be the problem ?

Thanks in advance,

Rob

Fast Hampster

Welcome to the forum, Rob! I think that you should make it run first, and only after that start dealing with fuel supply problem. Backfiring usually means wrong ignition timing/firing order. Late timing also might cause a truck not to start when it's warmed up.

Just call me Sean

iTrader: (1)

It's probably the ignition control module. They like to cut out when they get hot. It can be tested at the parts store, but I don't know if that helps too much since it works when cool. I don't know if the test will show that it is bad because of the way it works. The module is a silver box mounted to the drivers side fenderwell. I don't think it is too expensive. Next time it stops running, check for spark. If there's no spark it's probably the module.

selrox

Thanks so far guys.

I agree, I have to get it running first.
But.....first thing tomorrow I have to change out the starter again

But after that I'll see if I have a spark and check out the ignition module.

Thanks again...........sofar.

I'll be back..............

Fast Hampster

Have you checked starter solenoids?

selrox

Well......... replaced starter again this morning.
Guess what...... the gear on the starter completely broke to pieces.
Not bad for a 3 day old starter huh
Anyway, checked the flywheel to make sure that was ok and it was Pfew...
Guy at autozone told me this happens sometimes when the starter doesn't retract fast enough.
Also took the ignition control module in for a test, passed with flying colors.
But like you guys said , that doesn't say much since it tends to act up when its warmed up.
I did notice when I took the plugs of the module there was a lot of white stuff in there.
My guess is that is that stuff you put on electrical plugs to keep moisture out ? Could that cause an intermittent problem ?
I cleaned the plugs out just in case
Have the truck running as we speak so will see what happens when its warmed up.

Will keep you guys posted.

Thanks

Rob

selrox

Ok, had the truck running for 10 minutes and then it just died.
Checked the module with an old sparkplug connected to the wire coming from the coil. Has spark ???
pumped the pedal and didn't see gas squirting in the carb so still a fuel problem.
However I poured some gas in the carb to make sure that there is gas in there.That should start it up right ? At least for a few seconds.
No such luck, won't start.
How much gas do I have to pour in there in order to get it to fire up ?


I'm puzzeled now.....

Really need some more help guys

Thanks

Rob

Just call me Sean

iTrader: (1)

To give a rough estimate, about 1/4 cup of gas should be fine to start it. After pouring in the gas, you may have to floor it to start it. I still think it's the module. What color was the spark? I forget what color a weak spark is but you should check the spark cold (when it usually runs) and note the color, then run it until it dies and check the color of the spark again. Even though it's sparking I think the spark is too weak for it to run.

Fast Hampster

I think that any spark can keep a warm engine running, especially with new plugs. On the other hand, a gas inside of a carb cam is enough to keep it running for 2-3 minutes, not 10. So if it starts right up it's probably not the fuel supply. There is a small chance that gas is boiling inside of a mechanical pump when the engine worms up, but in this case it would also take more time to start it cold after this, and i think that this option is mostly for russian cars.

Here's what i'm thinking - let's go in reverse. Timing is fine(at least close) because it works fine. Spark is at it's place, and most of ignition related parts are new. Valve timing can't affect this way. So anyway it looks like it runs out of fuel or we're facing a weird carb problem. To make a carb run out of fuel, it only takes a needle valve to stuck halfway down. And another idea is a major intake vacuum leak getting bigger as the engine warmes up. I can't figure out anything elce now.

Just call me Sean

iTrader: (1)

I don't think it's a fuel issue, because even if the carb or pump is malfunctioning it should still run when fuel is poured down the carb. You said you changed the plugs and wires, what about the cap and rotor? If you haven't changed them yet, now is the time. One other thing that hasn't been mentioned yet, inspect the distributor components. Make sure the vacuum advance is getting vacuum and isn't seized, and make sure the mechanical advance springs and weights are intact and not frozen in place.