coolp51d

Hi everyone,
I put this in the "general" category, but this section is probably more appropriate. Sorry for flooding the forum with duplicate posts

I have a 1984 f150 manual with the 300 straight six (carbureted). It has been developing a frustrating problem. It used to only happen once or twice in the start of a drive for just a couple seconds, but now it is almost constant. It idles fine, but as soon as I accelerate it bogs down and makes more of a "chugging" noise. It doesn't lurch or surge or any of that, just a smooth, weak, no-power type of thing. It does it accelerating and going uphill, and it seems REALLY bad in the low rpm's. I can feel the true power of the engine just when I start out from a stop and sometimes on shifting, but it instantly bogs out.

Less than a year ago I gave it new plugs, wires, cap, rotor, O2 sensor, fuel filter at carb. and it was running great for several months, then it slowly began having the problem. Just today I gave it new plugs (I broke one pulling them out for inspection so I figured I'd splurge on a new set) and shot the carb with some cleaner, but to no avail! Just looking for some input on possible problems or ways to rule out certain problems.

Thanks much!
-Thomas

BillyBobFord97

sounds kind of like a timing issue

coolp51d

Yeah, when it was doing it a little before, I checked the ignition timing and it was fine; I suppose I should check it tomorrow morning just to make sure. My mind does keep wandering back to timing, so thanks for the comment.
-Thomas

Oldrusty

If your base timing checks ok, check the timing advance and make sure its working. If thats all good your carb may not be getting enough fuel.

You've changed the filter at the carb,you may need to change it again.
Check to see if there is more than one filter on the system. There should be a screen on the pickup tube in the tank,its possible that it is clogged.

What about the air filter,when was it last changed?

coolp51d

Oh yeah, I forgot to mention the air filter! It was changed about 6 months ago, I checked it yesterday and it's nice and clean. About the pickup screen, what is the best way to get to it? I have 2 tanks, so I'm assuming there's one in each? I'll go out and check the timing and look to see if there is another filter after my late lunch.
-Thomas

coolp51d

Well don't I feel silly? The timing wasn't just off, it was WAY WAY off! When I disconnected the advance, the engine just started put-putting, so I shined the timing light and I could hardly believe it...past 6 degrees retarded! It was almost off the scale! So, I set the base timing, checked the advance, and it drives like a champ. Just like me to assume my timing hadn't slipped...
I don't understand how it slipped though; the distributor hold-down bolt was REALLY tight, and the distributor didn't budge until it was loosened, but somehow it got 16-17 degrees off. Oh well, problem solved for free!

Thanks for the help,
Thomas