Hey y’all. So I have an 84 f150 that’s currently not running and I’ve come here for some help hopefully. So here’s the run down..

its an 84 with an 87 motor. The guy I bought it from switch from EFIto a carb (which I really don’t mind) and swapped the duraspark system to points (kinda dumb in my opinion). So I picked the truck up and drove it home fine. Two days after having it, it refused to start. I first thought it was fuel problem. I’ve check the pressure and it’s all good. Come to find out it seemed like it was burning out the points. I changed the points and it’ll run really well till it reaches operating temp then it’ll slow die. I got a pertronix ignitor to try that...again it’ll run fine until it reaches temp and then slowly dies. The pertronix is getting full 12 volts. When it dies it will start back up usually but it’s extremely hard. If I can get it started if I hold the gas pedal down a bit it will stay running.

Ive change the starter relay, coil, plugs. I’ve cleaned all engine grounds and battery terminals. I’ve checked fuel pressure coming from electric fuel pump and I’m getting proper fuel pressure. I plan to get the parts to swap it back to duraspark, though at this point I’m hoping it’ll fix it but not certain.

I think my my next step is to check the carb float...when it does that’s how it feels..like the float maybe stuck. But I’m honestly not sure. I was hoping for some advise. Thanks in advance.

 

If it will not crank at all you have a electrical problem.

If it cranks, but slow and struggles when hot, but cranks ok when cooled off, your timing is set too advanced.

If it's burning the points up, the resistor is missing in the coil circuit, it should have 9 volts not 12 volts when running. If the pertronix requires a resistor, same thing for it. If the pertronix does not require a resistor, then it should be ok.

Another thing you can try is a spark tester from harbor freight. When it slowly dies check for spark quality with the checker. Here's what it looks like.

 

WOW batman that picture is LARGE!

Welcome to FTE.

You said a few things that brings up questions.
What motor are we working on?
What is the "proper fuel pressure"?
What electric pump is this truck running, factory in tank or factory frame mount or after market pump and if so where is it mounted?
What carb is on the motor?

It sounds like it could be fuel but need make sure so we know what path to go down.
Dave ----

 

Thanks for the reply. I did a spark test before I replace the coil. It had spark but was weak. Tested the coil and it was definitely busted. Now it definitely has spark. According the pertronix instructions you don’t need a resistor. It needs a full 12v. Also, when it cranks, it cranks properly..notnlike a dead battery or anything..it’s just really hard for it to actually run. But it really wants to.

 

The motor is a 302. The fuel pressure is between 5-7psi if I recall correctly. The only fuel pump I’m aware of (I haven’t dropped the tank nor do I see any wires coming from it) is an aftermarket Mr. Gasket fuel pump mounted to the frame under the truck. The carb is a 4 barrel edelbrock..I can’t recall the model number at the moment but I can verify when I get home...1405 maybe? I could be wrong.

 

Is the exhaust stock? Is the fuel pump and fuel lines run like originals over on the driver's side with the exhaust on the pass side?

 

Exhaust is stock as far as I can tell. And yeah, the fuel lines are on the drivers side, exhaust on pass. Though there are no hard fuel lines..all flex.

 

Are the flex lines rubber from the store? Or are they the factory plastic lines? Sometimes those rubber lines are wound too tight on the roll at the store, and they are not round but oval and have a tendency to want to collapse.

What you can do is the next time it dies and doesn't want to run, take the air cleaner off, and while looking down the carb throat push back on the throttle quickly. You should see two strong streams of gas pour into the engine down the carb throat. You should be able to do this several times. If it's not squirting consistently, then the carb is most likely running out of fuel and you have a fuel delivery problem.

 

Pretty sure they’re from the store. It was like that when I got it, but I also know that those aren’t my problem. I can see consistent gas for sure.

 

Ok you may want to check on Edelbrock's site to see what that carb should have for fuel PSI but most of them Edel carbs don't like more than 5 psi tops. For some reason the float, needle & seat cant take much psi and flood the carb. That then leads to fouled plugs and cant start.
May want to throw a new set of plugs in it, kill the fuel pump and see if it will start / run till the carb is out of fuel.
And if the plugs look new and only been in a little bit they can stall be bad.

I had a car that I only started to move when I had to maybe 2 or 3 times a year as I was working on it and no area to move it to.
Carb had an internal vacuum leak and ran lean. Went to start it and anything over an idle it would back fire out the exh. after checking things out traced it to a bad plug.
Plug looked like I just pulled it out of the box as did the others. Changed them all out and the motor ran like new, soon after the carb was replaced.
So you cant go by what the plugs look like, change them out. once running you can swap the others in 4 at a time to see if it will run on them.
Dave ----

 

Well Edelbrock site has this:
But as I posted I have heard of others having issues when running close to the 5 psi limit so lower the better but still supply fuel I hear.
Dave ----

 

For Carbs I prefer a mechanical fuel pump. Other than a carb issue, I'm wondering how it sounds when it starts to die. Does it start missing and cutting out more and more? Or does it start to bog more and more? If it's bogging then it's more than likely flooding, if it's cutting out then it's either lean, of it could even be a leaky intake seal.

 

The "bog more and more" could be a plugged cat or muffler also.
If it cant get rid of the air it took in thru the carb it will stop running till it "leaks" out then start back up till it happened again.
If you have an 02 port you can install a psi gauge and run it till it dies and see if the psi goes up till it dies.
Dave ----

 

So..to answer the questions were I last left off..it was slowly bogging out..coincidentally the same thing happened with my motorcycle and it was a stuck float...which got me thinking...

This past weekend I took apart the carb and check the floats...and lemme tell ya, those bowls will FILTHY! So I cleaned them out really nicely, made a small adjustment to the gap in the dizzy and it fired right up! So for the last few days I’ve been going outside periodically and starting it, letting it run, and taking it for a few laps around the neighborhood. So far so good! Let’s hope it stays that way.

I plan to add another inline fuel filter just for security reasons until I have the time to put in the new tank and mechanical fuel pump I have waiting.

 

I was thinking the same thing honestly as far as the cats. They still could be a bit clogged. Not sure if I have an o2 port or not, but I may or may not just cut em out.