Hi everyone. This is my first post so please be kind.
Warning: I'm a novice when it comes to vehicle maintenance. I'm learning a lot through my truck but there's so much more to learn.

My truck is a 1981 F-150 with a 302. It usually runs wonderful, excusing the standard cold start issues old trucks have.

My issue is that, as of 5 days ago, my truck has been idling very rough and stalling upon ignition. Once I turn the key to start it, it starts at a rev (I have to rev it or it just cranks endlessly) then the RPMs fall and it soon dies out. When I rev the engine to keep it alive and raise the engine temperature, then let it fall back to an idle, it's extremely harsh. It shakes the interior of the vehicle. It's uneven and sounds like it's stuttering.
PS, my friend was looking at it and said he heard a screech noise from under the hood when I started it. That's starting to make me think its the fuel pump but I have no idea. The fuel pump is mechanical and was replaced by the PO last year.
Think any of you guys can help me with this? I'd greatly appreciate it.

 

Any help will be amazing. For now, and until around noon, I'm going to sleep. I'll check around 12:30 for any talk. Thank you guys.

 

Once you get it going it runs ok correct? If that's the case it's not the fuel pump.

If you have never done a tune-up on this truck, that would not be money wasted. New plugs, rotor and distributor cap. Check the sparkplug wires. If they look nasty or they fall apart when you take them off the plugs, get some of those too.

If it's still acting up I suspect carb problems, and it probably needs a carb kit and a new fuel filter. All old Ford trucks do not have cold start problems. When they were new, one push of the pedal when cold, and they will crank right up and you can take off from there. It's all the old Ford trucks with carb problems and broken choke mechanisms that have a hard time starting.

Have you ever put a model car together? Rebuilding a carb is much like that. If you can carefully follow instructions, have a place to work, and have a few small tools, you can rebuild your own carb. Any questions just ask on here.

 

You can count on Dave's advice. That funny noise your friend heard may be a fan belt slipping. Check the tension on your belts. Richard

 

Dave-

Thing is, I actually did a tune up last week, about 3 days before it started acting like this. I changed the oil and filter, got new spark plugs and wires, and got a new air filter and fuel filter. I'll definitely go get a new distributor cap and rotor though. If that doesn't help, then, well, I'll take it from you that I have carb problems.

 

Check to make sure your spark plug wires are installed on the right locations of the cap and at each cylinder. If it suddenly started doing this after putting in new plugs I am guessing you crossed up your spark plug wires.

Also set your timing just to make sure that is good.

 

Ray-

Double-checked spark plug wires and they're fine. Sorry to ask but how would I set my timing?

 

Do you have a timing light and a shop manual/ Haynes manual for your truck?

 

I don't have a timing light but I do have a chilton's manual. I can go get a timing light and work it out tomorrow. If you could tell me the process if appreciate it.

 

Checking your timing 101

Make sure engine is at operating temperature if you can get it to run.

1. Hook up your timing light. Positive and Negative leads to positive and negative battery terminals. Induction sensor to #1 spark plug wire.

2. Locate timing mark indicator over crankshaft.

3. If you have EFI pull the SPOUT connector out to set base timing.

4. If you have a vacuum advanced distributor pull the vacuum line off the distributor to set base timing.

5. Look up in your chiltons manual to see what your base timing should be.

6. Start engine and point light at timing mark indicator (light will flash whenever it senses voltage in the #1 spark plug wire.)

7. Note timing. If it is correct you are done and you can replace the SPOUT connector or the Vacuum line.

8. If incorrect you need to rotate your distributor with the engine running and the timing light pointed at the indicator. As you rotate the distributor the timing will change. Rotate until desired timing is achieved and tighten the bolt to the distributor to lock it in place. (did I mention to loosen it first?) plug in your SPOUT or vacuum line and you are good to go.

Note 85/86 302 EFI base timing for stock engines should be 10BDTC (Before Top Dead Center) Top Dead Center is the highest point of the #1 cylinder on its compression stroke. So the spark plug fires as the crank is 10 degrees before TDC. This is called advanced timing. Retarded timing is when the spark fire after TDC, which you won't need to worry about for your truck. I am not sure what a carburated Ford base timing is. I am sure the pros on here can tell you that.

 

Think very carefully about it. It was running ok, you did a tune-up and it ran ok and then messed up or it starting running bad right after the tune-up? If it starting running bad pretty close to when you did the tune-up, I would check the components. If the engine is shaking badly, you might have a dead cylinder. I would loosen all the sparkplug wires on top of the dist cap so you can take them off easily, start the engine, and then using a glove and needle nose or some other pliers, lift the sparkplug wires off the distributor cap one at a time. When you do that the engine should run noticeably worse. If the engine doesn't on one of them, then that cylinder is dead. I would check this wire carefully, and pull the sparkplug. It's very easy for one of the ends to come off the sparkplug wire, or for the porcelain on one of the plugs to crack, I have done it myself many times when a plug is hard to get to and I can't get two hands on the ratchet when installing the plug.

If you do find a dead cylinder, and can't seem to find anything wrong, take a plug from one of the other cylinders and swap it and see if the problem moves. If it doesn't, then swap one of the wires with another one that is good, or a old one you think is good.

 

Also check your vacuum lines and any vacuum plugs. You may have bumped one loose while working on your tuneup

 

Hey guys, thank you all for the advice. The problem is fixed. Problem was the distributor cap and rotor. There was carbon tracking all over them. I got a new set and now we're running solid. Thank you guys for making my first thread on the forum so resourceful. I'm definitely gonna come to you guys for help. You guys have a good day.