Alrighty so I drove my '81 F-250 (4X4 w/460) around town and to and from work this weekend for the first time. Everything was running fantastic (with the exception of the brakes still, no biggie.) Well I had to stop to fill up at the gas station and as I was pulling into the station the idle become very very weak. It didnt die altogether but it got so faint! I filled the truck up with Mid Grade (Is that a decent octane to use?) but when I tried to crank the truck up it took a good 5-10 minutes to actually get the engine to crank up..and once it did it still had the deathly faint idle to it, The truck accelerated ok, but the second I took my foot off the gas it would damn near die. So it made it home at least and I let it sit for most of yesterday. It took me awhile once again to get it to crank and when it did ONCE AGAIN...the idle was soooo low I didnt even want to drive it to work today...It didnt die while I had it started in the drive way but it was still very weak.

Now Im not sure how often the truck was driven from the previous owner but I know it was a farm truck. I thought maybe the fact that I was running the truck for like 40 miles at over 70MPH and the truck had a hard time adjusting....I dont know. What should I try ya'll?

 

sounds like what mine is doing... takes it a while to warm up - i think i have a bad carb though ... gonna replace it with an edlebrock in a month or so - after i fix the brakes... let me know what you find out.

 

To the best of my knowledge Ford didn't put 460's in '80-'82 F100-350's. Started again in '83. Maybe a previous owner swapped one in or possibly you have a 400. At any rate you could tighten down on the idle adjustment screw (also called "curb idle adjustment") and see if that helps. May be time for a good carburetor cleaning and "kit".

 

Does the exhaust smell like gas and smokes black? If so, I would suspect dirt has gotten in the carb.

 

Any broken/missing vacuum lines?

 

The dealership I bought it from said it was using a 460. Now you got me wondering. How many different engine combos were available for an '81 F250 4X4? I do have a gas smell, but I imagine it's an exhaust leak from probably more than one rusted out part of the exhaust. No smoke at all, so I can X that out....I will be checking tomorrow morning for vacuum leaks and hose issues too!

 

What's the truck's VIN number?...should be able to tell which engine it was built with from that.

 

VIN is: 1FTHF26Z0BPA92935

 

Engine code Z...your truck was built with a 400.

 

Those little ****s!! What is a 400 ?

 

It's a bored out 351M.

 

Keep in mind, that's what the truck was built with. It may not be what's in there now. Is it a two or four barrel carb?

 

I get off in about an hour...Im going to have to go look. I bought the truck for towing 5-600 mile intervals once a month but is thing gonna hold up to that even? If in fact I was bamboozled and it's not a 460?

 

I've owned a 351M, and that was a really strong engine. Unless you're planning to tow an awful lot of weight, I don't see you having trouble with the 400.

 

just a trailer big enough to carry around AT MOST...4000 LBS...