I just picked up a 1978 F250 with a stock 300-smog, 1bbl carb, manifolds, all that stuff. It runs good. Real smooth and great power and acceleration. I gave it a very minor tune up by adjusting the timing to about 7 degrees and adjusting the carb for max vacuum. The problem is this:

After it is warmed up, if I shut it off and then go to restart it, I have to HOLD the pedal on the floor to start it. Every time. It always starts, but I am sure that isn't right. My other truck with the modified 300 would barely have to crank over when warm and it would be running.

Since I am not familiar with the 1bbl and smog stuff, could somebody maybe tell me where to start with this problem?

 

I'm far from sure but I think the cold start sequence is - push the gas to the floor gentily, release. Turn key w/o foot on pedal.
Have U tried that for warm starts? Look on the back of the carb to see how that linkage works. It may be a problem there (notches on linkage for engaging/disengaging choke may B rusted/bent/dammaged)?
Good Luck, let us know whas'up wid dat.

 

check and adjust the choke linkage, it may be sticking, and flooding out the motor on a hot start

 

crlsful-yes, but it won't start that way. I have to just hold it to the floor to get it to start.

The choke was suggested, but someone put on a manual choke. I am going to just rebuild the carb and retune. After 30 years, a $12 carb kit is probably money well spent.

 

Yup, sounds like its flooding if it requires you to hold the pedal to the metal to get to start when hot. When you rebuild the carb, check the throttle plate shaft for wear and rebush if necessary. This will save you a lot of driveability grief down the road.

 

I'd quess that the accel pump has a tiny hole in it, and is dripping fuel down the throat of the carb after shutting off the engine. A quick way to confirm this, pop off the air cleaner and run the engine till fully warmed up, shut off. Watch for signs of white-ish smoke drifting out of the top of carb.
Carb rebuild will fix this.

 

Thanks for the replies, guys. Last night I went and got a carb kit. I figured for $12, even if it didn't fix it, it was probably still money well spent. I will post up (for future reference) what fixes the problem.

 

what fixes the problem

Or Not, still here if desired...

 

I ended up putting in a new accelerator pump and an accelerator check ball and weight. There wasn't a ball in there when I tore it down, so I suspect that was to blame. Now it runs like a champ! Fires good cold, and barely touch the key when warm. I still need to fine tune it with the vacuum guage, but there is a significant improvement.

Thanks for your replies, guys!

 

78 F250 300 I6...nice score! Love that body style!

accelerator pump and an accelerator check ball and weight
For $12 I'm glad it fixed. I just rebuilt mine. I got a $30 kit that didn't fit (they gave me the wrong 1), went back for $60, n mine's a charm now too. Had it since '82 and seems like a totally new vehicle!

Any mods ahead for it?

 

Yeah, but I didn't fully state what I have going on. Here's the truck that started it all:
It came with a 300. Best engine I NEVER wanted That truck became this:

Sadly, a wife and 3 kids later, it wasn't that useful. However, after about 1 month after I sold it, I started looking and found this:


I was stoked when I found a 70s crew with a 300 and a 4spd

Even better-my wife is a patient lady. My plans for this truck are to drive it for quite a while and maybe eventually convert it to 4wd like the last one.

Anyway, that's my 300/old truck history

 

light green, dark green and now a crew! (1 pic looks like it was taken 'out west', where R U?). Cool! Again, I like that ('73 -79?) model. Saw 1 w/ a oem tool box under the bed, push button lock n everything!
Your wife must be an angel.
Yes, indeed, I noticed that "4WD conversion". Wish the newer 1s were as easy to swap.

 

I live in Idaho. As far as my wife, we are both lucky. I put up with her car obsession, and she tolerates my old truck problems.

One of the nice things about out here in the west is the relative lack of rust. Gotta love southern Idaho for that.

 

nice hard (to) find on the crew. keep that in the family

 

Yeah, I intend to keep it at least until my kids fly the coop. I had the regular cab for 9 years, so it's not like I just trade thru vehicles I figure the crew will be here for 18 or so.